2016-2018

Chevrolet Volt

Service Manual

ACCESSORIES & EQUIPMENT

Cellular, Entertainment, and Navigation - Volt

SPECIFICATIONS

FASTENER SPECIFICATIONS

Reusable Threaded Fastener Tightening Specifications

NOTE:

All fasteners
listed in this
table can be
reused after
removal.

Application

Specification

Metric (English)

Communication Interface Module Bracket Bolt

2.5 N.m (22 lb in)

High Frequency Antenna Nut

9 N.m (80 lb in)

Radio Control Bolt

2.5 N.m (22 lb in)

Radio Control Switch Bolt

2.5 N.m (22 lb in)

Radio Front Center Speaker Bolt

2.5 N.m (22 lb in)

Radio Front Side Door Speaker Fastener

2.5 N.m (22 lb in)

Radio Front Speaker Bolt

2.5 N.m (22 lb in)

Radio Rear Compartment Speaker Fastener

6 N.m (53 lb in)

Radio Rear Side Door Speaker Fastener

2.5 N.m (22 lb in)

Radio Speaker Amplifier Bracket Bolt

9 N.m (80 lb in)

SCHEMATIC WIRING DIAGRAMS

RADIO/NAVIGATION SYSTEM WIRING SCHEMATICS

Power, Ground, Antenna and Data Communication

Fig. 1: Power, Ground, Antenna and Data Communication
Courtesy of GENERAL MOTORS COMPANY


Amplifier Inputs (UQA)



Fig. 2: Amplifier Inputs (UQA)

Courtesy of GENERAL MOTORS COMPANY

Auxiliary Audio Input

Fig. 3: Auxiliary Audio Input

Courtesy of GENERAL MOTORS COMPANY

Info Display

Fig. 4: Info Display

Courtesy of GENERAL MOTORS COMPANY


Speakers (UQA)


Fig. 5: Speakers (UQA)

Courtesy of GENERAL MOTORS COMPANY


Speakers (UZ6)


Fig. 6: Speakers (UZ6)

Courtesy of GENERAL MOTORS COMPANY

ONSTAR/TELEMATICS WIRING SCHEMATICS

OnStar Schematics

Fig. 7: OnStar Schematics

Courtesy of GENERAL MOTORS COMPANY


CELLULAR TELEPHONE WIRING SCHEMATICS

Cellular Telephone Microphone (-UE1)


Fig. 8: Cellular Telephone Microphone (-UE1)
Courtesy of GENERAL MOTORS COMPANY

DIAGNOSTIC INFORMATION AND PROCEDURES

DTC B0997: AUXILIARY ELECTRONIC CONTROL UNIT PERFORMANCE

Diagnostic Instructions

DTC Descriptor

DTC B0997 3A

Auxiliary Electronic Control Unit Performance Incorrect Component Installed

DTC B0997 39

Auxiliary Electronic Control Unit Performance Internal Electronic Failure

Circuit/System Description

The info display module monitors itself for internal failures and reports its condition to the Human Machine
Interface Control Module when requested. The info display also reports electronic identification information when
requested.

Conditions for Running DTC

Conditions for Setting the DTC

B0997 3A

The Info Display Module has reported identification information that differs from the information calibrated in the
Human Machine Interface Control Module.

B0997 39

The Info Display Module reports an internal malfunction.

Action Taken When DTC Sets

The Human Machine Interface Control Module will set the DTC and the Info Display Module will have limited or no
functionality.

Conditions for Clearing the DTC

The Human Machine Interface Control Module detects a compatible Info Display Module with no internal
malfunctions reported.

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Refer to Diagnostic Trouble Code (DTC) List - Vehicle .

Replace the P17 Info Display Module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to Radio Control Assembly Replacement

DTC B1024: CIRCUIT BOARD TEMPERATURE SENSOR ABOVE MAXIMUM THRESHOLD (AUDIO
AMPLIFIER)

Diagnostic Instructions

DTC Descriptor

DTC B1024 11

Circuit Board Temperature Sensor Above Maximum Threshold

Circuit/System Description

The audio amplifier monitors the internal circuitry for excessive temperature. When the amplifier senses an internal
circuitry temperature greater than 95A°C (203A°F), the amplifier will set DTC B1024 11 and shut down until the
internal circuitry cools below 90A°C (194A°F). No external circuit diagnosis is involved.

Conditions for Running the DTC

Conditions for Setting the DTC

The audio amplifier detects an over-heat condition greater than 95A°C (203A°F) of the internal amplifier circuitry.

Action Taken When the DTC Sets

The audio amplifier will shut down and all speakers will be inoperative.

Conditions for Clearing the DTC

Diagnostic Aids

Extended use or extremely high volume especially in warm weather conditions may cause this DTC to set. Under
these conditions it may be normal for this DTC to set to prevent permanent damage to the audio amplifier circuitry.

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

NOTE: Allow the vehicle cabin to cool if the temperature inside the vehicle is excessive
before proceeding with this diagnostic procedure.

The system is operating as designed, All OK.

experienced the concern.

Replace the T3 Audio Amplifier

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Refer to Control Module References for audio amplifier replacement, setup, and programming

DTC B1024: CIRCUIT BOARD TEMPERATURE SENSOR THRESHOLD

Diagnostic Instructions

DTC Descriptor

DTC B1024 53

Circuit Board Temperature Sensor Below Minimum Threshold

DTC B1024 54

Circuit Board Temperature Sensor Above Maximum Threshold

Circuit/System Description

The human machine interface control module monitors the internal circuitry for excessive temperature. When a
temperature outside of the range is detected, the module sets the DTC and limits its operation to avoid damage.

Conditions for Running the DTC

Conditions for Setting the DTC

B1024 53

The module senses an internal temperature less than -40A°C (-40A°F).

B1024 54

The module senses an internal temperature greater than 69A°C (156A°F).

Action Taken When the DTC Sets

Conditions for Clearing the DTC

Diagnostic Aids

Under certain conditions it may be normal for this DTC to set to prevent permanent damage to the module.

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

NOTE: Allow the vehicle cabin to cool if the temperature inside the vehicle is excessive
before proceeding with this diagnostic procedure.

• If the DTC sets within the Conditions for Running and Setting.

The system is operating as designed, All OK.

Replace the K74 Human Machine Interface Control Module

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to Control Module References for human machine interface control module replacement, programming, and
setup.

DTC B1025-B1135: AUDIO OUTPUT CIRCUITS

Diagnostic Instructions

DTC Descriptors

DTC B1025

Audio Output 1 Circuit

DTC B1035

Audio Output 2 Circuit

DTC B1045

Audio Output 3 Circuit

DTC B1065

Audio Output 5 Circuit

DTC B1075

Audio Output 6 Circuit

DTC B1085

Audio Output 7 Circuit

For symptom byte information refer to Symptom Byte List .

Diagnostic Fault Information

Circuit

Short to
Ground

Open/High

Resistance

Short to
Voltage

Signal
Performance

Audio Output 1 Signal Circuits
(Left Front Door and tweeter)

B1025 02

B1025 04

B1025 01

-

Audio Output 2 Signal Circuits
(Right Front Door and tweeter)

B1035 02

B1035 04

B1035 01

-

Audio Output 3 Signal Circuits
(Rear Subwoofer)

B1045 02

B1045 04

B1045 01

-

Audio Output 5 Signal Circuits
(Left Rear Door)

B1065 02

B1065 04

B1065 01

-

Audio Output 6 Signal Circuits
(Right Rear Door)

B1075 02

B1075 04

B1075 01

-

Audio Output 7 Signal Circuits
(Center I/P)

B1085 02

B1085 04

B1085 01

-

Circuit/System Description

The Media Oriented Systems Transport (MOST) is a high-speed multimedia network technology. The serial MOST
bus uses a ring topology and synchronous data communication to transmit audio, video, data and control information
between any devices attached.

The audio amplifier is a participant on the MOST network. The audio amplifier receives audio inputs and control
information from the MOST bus.

Each of the audio output channel circuits (+) and (-), at the audio amplifier have a DC bias voltage that is
approximately one half of the battery voltage. When using a DMM, each of the audio output channel circuits will
measure approximately 6.5 V DC. The audio being played on the system is produced by a varying AC voltage that is
centered around the DC bias voltage on the same circuit. The AC voltage is what causes the speaker cone to move
and produce sound.

Diagnostic Aids

The EL-50334-6 Audio System Diagnostic CD contains audio tracks that can be used to duplicate and isolate
such concerns. Tracks 11 and 12 contain audio sweep tones for testing for speaker and grill rattles.

If the speaker or surrounding interior trim is found to be loose or improperly secured, correctly secure the item.

Conditions for Running the DTC

NOTE: DTC B1325 must not be set as current for the amplifier to run any of the following
tests.

DTC B1025 01, B1035 01, B1045 01, B1065 01, B1075 01, B1085 01

The test is run initially upon amplifier wake-up, and periodically every one second after amplifier operation begins.

DTC B1025 02, B1035 02, B1045 02, B1065 02, B1075 02, B1085 02

The test is run initially upon amplifier wake-up, and periodically every one second after amplifier operation begins.

DTC B1025 04, B1035 04, B1045 04, B1065 04, B1075 04, B1085 04

The test is run once during amplifier wake-up.

Conditions for Setting the DTC

DTC B1025 01, B1035 01, B1045 01, B1065 01, B1075 01, B1085 01

A short to voltage is detected on the specified (+) or (-) signal circuit

DTC B1025 02, B1035 02, B1045 02, B1065 02, B1075 02, B1085 02

A short to ground is detected on the specified (+) or (-) signal circuit

DTC B1025 04, B1035 04, B1045 04, B1065 04, B1075 04, B1085 04

An open is detected on the specified (+) or (-) signal circuit

Action Taken When the DTC Sets

The amplifier mutes the output channel and no sound is present from the speaker(s) that have a current circuit fault.

Conditions for Clearing the DTC

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Electrical Information Reference

Circuit Testing

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Special Tools

EL-50334-50 USB Cable and Adapter Kit

Circuit/System Verification

Refer to Circuit/System Testing.

Circuit/System Testing

NOTE: Some circuits supply audio signals to more than one speaker. It may be
necessary to disconnect all speakers on the affected audio circuit when
performing circuit tests.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

DTC B124B: USB 1 CIRCUIT

Diagnostic Instructions

DTC Descriptor

DTC B124B

USB 1 Circuit

For symptom byte information refer to Symptom Byte List .

Diagnostic Fault Information

Circuit

Short to
Ground

Open/High
Resistance

Short to
Voltage

Signal
Performance

B+

B124B, 2

B124B, 1

-

-

USB Cable

B124B

B124B

B124B

-

Ground

-

1

-

-

  • 1. Fault may affect one or more components, dependant on fault location

  • 2. Fault affects multiple components, dependant on vehicle equipment

Circuit/System Description

The infotainment system has a USB port and a Auxiliary Audio Input Jack located in the center console. The
receptacle assembly receives fused battery voltage and ground from the harness to power the internal hub device as
well as providing additional amperage to power USB devices.

The internal hub device interfaces directly with the human machine interface control module via a standard USB
cable. A Mini type USB connector is used to connect the human machine interface control module and the USB
receptacle. Standard USB male to female connections are typically used for connecting USB cables together where
an in-line connection is required. An in-line cable connection is typically found between the console and I/P harness.

Auxiliary Audio Input Jack

When a portable audio playback device is connected to the 3.5 mm (1/8 in.) auxiliary audio input jack an internal
switch opens the detection signal circuit within the hub. The HMI detects the device and AUX becomes available as
an audio source. Audio signals from the device are converted from analog to digital, these signals are then sent to the
HMI from the auxiliary input jack via USB.

USB Port

The USB port allows connectivity to the infotainment system from portable media players or a USB storage device
(memory stick/flash drive). When a device is connected to the USB port, the system detects the device and switches
to USB as the audio source. Once connected, the device can be controlled from the radio controls.

Not all portable media player devices or file types are compatible. Refer to the owner's manual for information on
USB devices, control, and operation.

Conditions for Running the DTC

Conditions for Setting the DTC

B124B 0B

The human machine interface control module detects an excessive current condition on the USB 5 V circuit.

B124B 04

The human machine interface control module does not detect the vehicle hub device.

B124B 11

The human machine interface control module detects an additional hub device attached to the vehicle USB port.

Action Taken When the DTC Sets

The USB port is inoperative while the DTC is current.

Conditions for Clearing the DTC

Diagnostic Aids

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Special Tools

Circuit/System Verification

Refer to Circuit/System Testing.

Refer to Circuit/System Testing

Refer to Circuit/System Testing

Refer to Circuit/System Testing

• If audio is heard from the test tool.

Circuit/System Testing

Perform the appropriate repair or replacement to correct any issues.

Module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

DTC B124F: UNIVERSAL SERIAL BUS (USB) PROGRAMMING

Diagnostic Instructions

DTC Descriptor

DTC B124F

Universal Serial Bus (USB) Programming

For symptom byte information, refer to Symptom Byte List .

Circuit/System Description

Certain devices in the entertainment system must be programmed with specific software and other information to
operate correctly. This DTC is the result of an unsuccessful USB programming event of the device. The symptom
byte information is for engineering reference only. No external circuit diagnosis is involved

Conditions for Running the DTC

Once upon each USB Programming Event.

Conditions for Setting the DTC

The programming event was incomplete, or completed with errors.

Action Taken When the DTC Sets

The entertainment system has limited or no functionality.

Conditions for Clearing the DTC

The programming event completes successfully.

Circuit/System Verification

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to Control Module References for device replacement, programming, and setup.

DTC B125A: ANTENNA SIGNAL CIRCUIT

Diagnostic Instructions

DTC Descriptors

DTC B125A 02

Antenna Signal Circuit Short to Ground

DTC B125A 04

Antenna Signal Circuit Open Circuit

DTC B125A 01

Antenna Signal Circuit Short to Battery

Diagnostic Fault Information

Circuit

Short to
Ground

Open/High
Resistance

Short to
Voltage

Signal
Performance

Circuit

Short to
Ground

Open/High
Resistance

Short to
Voltage

Signal
Performance

Radio Antenna Coax

B125A 02

B125A 04

B125A 01

-

Circuit/System Description

The radio antenna for AM and FM radio reception is connected to the radio with a coaxial cable.

Conditions for Running the DTC

Conditions for Setting the DTC

B125A 02

The radio detects a short to ground in the antenna signal circuit center conductor.

B125A 04

The radio detects an open in the antenna signal circuit center conductor.

B125A 01

The radio detects a short to battery in the antenna signal circuit center conductor.

Action Taken When the DTC Sets

Radio reception may be poor or not available.

Conditions for Clearing the DTC

Diagnostic Aids

Poor AM and FM radio reception is dependent on multiple influences, some of which may not be vehicle related.
Areas which have high RF traffic or block the signal path may cause a degradation in radio reception. Radio
reception may also be influenced by items within the vehicle, but are not part of the radio system. Such examples are
aftermarket electrical accessories or other items which may generate noise in the vehicle electrical system.

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Repair or replace as necessary

Refer to Circuit/System Testing

Circuit/System Testing

Replace the antenna coax cable

Replace the radio antenna base.

Component Testing

CAUTION: Refer to Test Probe Caution .

NOTE: Before testing the coax cable, check the cable exterior for being pinched, cut,
damaged, or having loose connections at the components, which can cause
reception issues.

To prevent false reading when testing the center coax terminals, use care not to
ground the test probe on the outer housing/shield.

Coax Cable Test

Replace the coax cable

Replace the coax cable

Replace the coax cable

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

DTC B125C: SATELLITE ANTENNA CIRCUIT

Diagnostic Instructions

DTC Descriptors

DTC B125C 01

Satellite Antenna Circuit Short to Battery

DTC B125C 02

Satellite Antenna Circuit Short to Ground

DTC B125C 04

Satellite Antenna Circuit Open

Circuit/System Description

The digital radio receiver, located inside the radio, receives digital radio information from the digital radio antenna
located on the outside of the vehicle. The digital radio receiver is connected to the digital radio antenna via a shielded
coax cable. The digital radio antenna contains an amplifier which is powered by the radio through the coax cable.

Conditions for Running the DTC

This DTC is run every 300 milliseconds.

Conditions for Setting the DTC

The radio detects a circuit fault in the digital radio antenna.

Action Taken When the DTC Sets

The radio displays No XM Signal or Check Antenna.

Conditions for Clearing the DTC

Diagnostic Aids

The digital radio antenna requires a clear line of sight to the sky to operate properly. Reception may be limited,
intermittent, or unavailable inside structures.

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Special Tools

EL-48028 Digital Radio Test Antenna

Circuit/System Verification

Refer to Circuit/System Testing.

Circuit/System Testing

Replace the A11 Radio.

Replace the antenna coax cable

Component Testing

CAUTION: Refer to Test Probe Caution .

NOTE: Before testing the coax cable, check the cable exterior for being pinched, cut,
damaged, or having loose connections at the components, which can cause
reception issues.

To prevent false reading when testing the center coax terminals, use care not to
ground the test probe on the outer housing/shield.

Coax Cable Test

Replace the coax cable

Replace the coax cable

Replace the coax cable

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

DTC B1271: THEFT PROTECTION ACTIVE

Diagnostic Instructions

DTC Descriptor

DTC B1271 00

Theft Protection Active

Circuit/System Description

When the radio is initially installed in the vehicle, the radio receives VIN information via serial data. The radio stores
a portion of the VIN and compares this sequence to the VIN information received each time the radio powers on. The
VIN in the radio is a single one-time learn.

The radio theft deterrent system is intended to disable or limit radio functionality if incorrect vehicle information is
received by the radio. The radio disables functionality if the VIN information received by the radio does not match
the VIN information that has been learned by the radio. This DTC is generated by the module when the Theft
Protection is activated.

Conditions for Running the DTC

This DTC test runs when the radio changes from OFF to ON.

Conditions for Setting the DTC

The radio has learned a correct VIN sequence and the VIN information received via serial data does NOT match the
learned VIN sequence.

Action Taken When the DTC Sets

The radio may be disabled or have limited functionality. The radio display will indicate that theft protection is active.

Conditions for Clearing the DTC

The radio receives the correct VIN information via serial data.

Diagnostic Aids

A possible cause of incorrect VIN info could be the radio was originally installed in another vehicle.

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Replace the A11 Radio.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to Control Module References for radio replacement, programming, and setup.

DTC B127E: FRONT VIDEO DISPLAY OUTPUT SIGNAL

Diagnostic Instructions

DTC Descriptor

DTC B127E 00

Front Video Display Output Signal

Circuit/System Description

The infotainment display and controls are a separate component from the radio, combined into an assembly. The
assembly is supplied battery voltage and ground from the vehicle harness. The human machine interface control
module communicates digital video data for on-screen display through a dedicated cable containing the LVDS data
circuits.

Control information, touch communications and dimming level for the display are communicated via a LIN serial
data circuit to the human machine interface control module.

If the human machine interface control module detects the display is not responding to the output on the LVDS
circuits, the human machine interface control module sets the DTC.

Conditions for Running the DTC

Conditions for Setting the DTC

The human machine interface control module detects the display is not responding to the output on the LVDS
circuits.

Action Taken When the DTC Sets

Conditions for Clearing the DTC

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Special Tools

Circuit/System Testing

All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

DTC B12A8: OPTICAL MEDIA DRIVE THEFT LOCKED

Diagnostic Instructions

DTC Descriptor

DTC B12A8 00

Optical Media Drive Theft Locked

Circuit/System Description

When the Media Disc Player is initially installed in the vehicle, it receives VIN information via serial data. The
Media Disc Player stores a portion of the VIN and compares this sequence to the VIN information received each
time the Media Disc Player powers on. The VIN in the Media Disc Player is a single one-time learn.

The Media Disc Player theft deterrent system is intended to disable or limit Media Disc Player functionality if
incorrect vehicle information is received by the Media Disc Player. The Media Disc Player disables functionality if
the VIN information received by the Media Disc Player does not match the VIN information that has been learned by
the Media Disc Player. This DTC is generated by the module when the Theft Protection is activated.

Conditions for Running the DTC

This test runs once per second while the Media Disc Player is being accessed.

Conditions for Setting the DTC

The Media Disc Player has learned a correct VIN sequence and the VIN information received via serial data does
NOT match the learned VIN sequence.

Action Taken When the DTC Sets

The Media Disc Player may be disabled or have limited functionality.

Conditions for Clearing the DTC

The Media Disc Player receives the correct VIN information via serial data.

Diagnostic Aids

A possible cause of incorrect VIN information could be the Media Disc Player was originally installed in another
vehicle.

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Replace the A33 Media Disc Player.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to Control Module References for media disc player replacement, programming, and setup.

DTC B1446 OR B1447: BACKUP POWER SOURCE

Diagnostic Instructions

DTC Descriptors

DTC B1446

Replace Backup Power Source Below Minimum Threshold

DTC B1447

Backup Power Source Open Circuit

For symptom byte information refer to Symptom Byte List

Diagnostic Fault Information

Circuit

Short to
Ground

Open/High
Resistance

Short to
Voltage

Signal
Performance

Backup Battery B+

B1447 03

B1447 04

-

-

Backup Battery Low Reference

B1447 03

B1447 04

-

-

Circuit/System Description

The backup power source provides voltage to the telematics communication interface control module, to be able to
successfully place a call in the event of a main battery disconnect during a collision event.

Conditions for Running the DTC

B1446 03

B1447 04

Conditions for Setting the DTC

B1446 03

The telematics communication interface control module detects that the backup power source voltage has dropped
below the minimum threshold value.

B1447 04

The telematics communication interface control module detects no voltage from the backup power source.

Action Taken When the DTC Sets

B1446 03

The OnStarA® status LED turns red.

B1447 04

Conditions for Clearing the DTC

Diagnostic Aids

• DTC B1447 may set if the K73 Telematics Communication Interface Control Module has been incorrectly
disconnected or serviced. When disconnecting the K73 Telematics Communication Interface Control Module,
disconnect the harness connector X1 at the K73 Telematics Communication Interface Control Module prior to
disconnecting any other harness connectors. This will ensure the backup power source is preserved when
voltage is removed from the K73 Telematics Communication Interface Control Module.

Reference Information

Schematic Reference

OnStar/Telematics Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

OnStar Description and Operation

Electrical Information Reference

Testing for Intermittent Conditions and Poor Connections

Circuit Testing

Wiring Repairs

Connector Repairs

Circuit/System Testing

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

DTC B2455: CELLULAR PHONE MICROPHONE CIRCUIT

Diagnostic Instructions

DTC Descriptors

DTC B2455 02

Cellular Phone Microphone Circuit Short to Ground

DTC B2455 04

Cellular Phone Microphone Circuit Open

Diagnostic Fault Information

Circuit

Short to
Ground

Open/High
Resistance

Short to
Voltage

Signal
Performance

Microphone Signal

B2455 02

B2455 04

B2455 04

-

Microphone Low Signal

B2455 02

B2455 04

B2455 04

-

Circuit/System Description

The telematics communication interface control module provides the cellular phone microphone with a supplied
voltage on the cellular phone microphone high signal circuit. When the microphone is in use, voice data from the
user is sent back to the telematics communication interface control module on the microphone low signal circuit.

Conditions for Running the DTC

Conditions for Setting the DTC

B2455 02

The telematics communication interface control module detects a short to ground in the cellular phone microphone
signal circuit for 10 s or greater.

B2455 04

The following conditions will set this DTC:

Action Taken When the DTC Sets

Conditions for Clearing the DTC

Reference Information

Schematic Reference

OnStar/Telematics Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

OnStar Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing

• If less than 8.0 V

• If less than infinite resistance, repair the short to ground in the circuit.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

DTC B2462: GLOBAL POSITIONING SYSTEM

Diagnostic Instructions

DTC Descriptors

DTC B2462 02

Global Positioning System Short to Ground

DTC B2462 04

Global Positioning System Open

Circuit/System Description

The navigation antenna is connected to the Telematics Communication Interface Control Module. The module
supplies 5 V to the antenna to power the internal amplifier through the center conductor of the antenna coax cable.

When the vehicle is equipped with the optional navigation system, a Navigation Antenna Signal Splitter is installed
to distribute the navigation signal to both the Telematics Communication Interface Control Module and the Human
Machine Interface Control Module. The Human Machine Interface Control Module supplies 5 V through the coax
cable to power the Navigation Antenna Signal Splitter.

Conditions for Running the DTC

Conditions for Setting the DTC

B2462 02

The Telematics Communication Interface Control Module or Human Machine Interface Control Module detects a
short to ground on the GPS antenna signal circuit.

B2462 04

The Telematics Communication Interface Control Module or Human Machine Interface Control Module detects a
open/high resistance on the GPS antenna signal circuit.

Action Taken When the DTC Sets

Conditions for Clearing the DTC

Diagnostic Aids

Reference Information

Schematic Reference

OnStar/Telematics Schematics

Radio/Navigation System Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

OnStar Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Special Tools

EL-49903 OnStar Antenna Diagnostic Tool Kit

Circuit/System Verification

NOTE: The following verification requires the vehicle to be outside with an unobstructed
view of the southern sky. Allow 5 minutes after turning the ignition ON for the
vehicle to acquire the GPS satellites signal.

Refer to Circuit/System Testing Without Navigation System.

Refer to Circuit/System Testing With Navigation System.

Refer to Circuit/System Testing Without Navigation System

Refer to Circuit/System Testing With Navigation System.

Refer to Circuit/System Testing With Navigation System - Step 9.

Refer to Circuit/System Testing With Navigation System - Step 9.

Circuit/System Testing

without Navigation System

NOTE: You must perform the Circuit/System Verification before proceeding with
Circuit/System Testing.

• If DTC B2462 is set or the advisor can not locate the vehicle

Replace the K73 Telematics Communication Interface Control Module.

Replace the coax cable.

with Navigation System

NOTE: You must perform the Circuit/System Verification before proceeding with
Circuit/System Testing.

Replace the coax cable.

Replace the K73 Telematics Communication Interface Control Module.

Communication Interface Control Module. Refer to Component Testing.

Replace the coax cable.

Replace the K74 Human Machine Interface Control Module

Replace the coax cable.

Component Testing

CAUTION: Refer to Test Probe Caution .

NOTE:

  • • Before testing the coax cable, check the cable exterior for being pinched, cut,
    damaged, or having loose connections at the components, which can cause
    reception issues.

  • • To prevent false reading when testing the center coax terminals, use care not
    to ground the test probe on the outer housing/shield.

  • • The vehicle may be equipped with sectioned coax. Test each section and
    replace only the faulty section, not the entire length of coax.

Coax Cable Test

Replace the coax cable.

Replace the coax cable.

Replace the coax cable.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

DTC B2470: CELLULAR PHONE ANTENNA CIRCUIT MALFUNCTION

Diagnostic Instructions

DTC Descriptors

DTC B2470 02

Cellular Phone Antenna Circuit Malfunction Short to Ground

DTC B2470 04

Cellular Phone Antenna Circuit Malfunction Open Circuit

Circuit/System Description

The primary cellular phone antenna element is connected to the telematics communication interface control module
(violet connector) via a shielded coaxial cable. Cellular communication takes place on both the primary cellular
antenna signal circuit and the GPS/secondary cellular antenna signal circuit. This diagnostic only applies to the
primary cellular antenna signal circuit. Internal to the antenna on the cellular antenna signal circuit resistance is used
to apply a load, which the telematics communication interface control module uses to detect the presence of the
antenna.

Conditions for Running the DTC

Conditions for Setting the DTC

B2470 02

The telematics communication interface control module detects a short to ground on the primary cellular antenna
signal circuit.

B2470 04

Action Taken When the DTC Sets

The OnStarA® status LED turns red.

Conditions for Clearing the DTC

Reference Information

Schematic Reference

OnStar/Telematics Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

OnStar Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Special Tools

EL-49903-1 Test Antenna Navn-Cell Comn

Circuit/System Testing

NOTE:

  • • The vehicle may be equipped with sectioned coax. Test each section and
    replace only the faulty section, not the entire length of coax.

  • • The following verification requires the vehicle to be outside with an
    unobstructed view of the southern sky. Allow 5 min after turning the ignition
    ON for the GPS satellites to acquire vehicle signal.

Replace the K73 Telematics Communications Interface Control Module.

Replace the coax cable.

Component Testing

CAUTION: Refer to Test Probe Caution

NOTE:

  • • Before testing the coax cable, check the cable exterior for being pinched, cut,
    damaged, or having loose connections at the components, which can cause
    reception issues.

  • • To prevent false readings when testing the center coax terminals, use care not
    to ground the test probe on the outer housing/shield.

Coax Cable Test

• If 5 fi or greater

Replace the coax cable.

Replace the coax cable.

Replace the coax cable.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair procedure.

DTC B2476 OR B2482: CELLULAR PHONE SELECT SERVICE SWITCH

Diagnostic Instructions

DTC Descriptors

DTC B2476 04

Cellular Phone Select Service Switch Open

DTC B2476 59

Cellular Phone Select Service Switch Protection Time-out

DTC B2482 00

Cellular Phone Select Service Switch Range/Performance

Diagnostic Fault Information

Circuit

Short to
Ground

Open/High
Resistance

Short to
Voltage

Signal
Performance

10 V Reference

B2476 02

B2476 04

B2476 04

-

Circuit

Short to
Ground

Open/High
Resistance

Short to
Voltage

Signal
Performance

Signal Terminal 17

B2476 02

B2476 04

B2476 59

B2476 59, B2482
00

Ground

-

B2476 04

-

-

Circuit/System Description

The OnStarA® button assembly consists of 3 buttons: Call/Answer, OnStarA® Call Center, and OnStarA®
Emergency. The telematics communication interface control module supplies the OnStarA® button assembly with 10
V via the 10 V reference circuit. Each of the buttons, when pressed, completes the circuit across a resistor allowing a
specific voltage to be returned to the telematics communication interface control module over the keypad signal
circuit. Depending upon the voltage range returned, the telematics communication interface control module is able to
identify which button has been pressed.

Conditions for Running the DTC

Conditions for Setting the DTC

B2476 04

The telematics communication interface control module detects an open/high resistance on the keypad supply
voltage circuit.

B2482 and B2476 59

The telematics communication interface control module detects a valid signal on the keypad signal circuit for longer
than 15 s. If one of the OnStarA® buttons is held or stuck for 15 s or greater, the telematics communication interface
control module will set this DTC.

Action Taken When the DTC Sets

Conditions for Clearing the DTC

Diagnostic Aids

After any repair is made to the 10 V reference circuit or button signal circuit the fuse to the telematics
communication interface control module must be removed for 30 s to reset the control module. Failure to do so could
result in incorrect diagnosis.

Reference Information

Schematic Reference

OnStar/Telematics Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

OnStar Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing

NOTE:

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

SYMPTOMS - CELLULAR COMMUNICATION

NOTE: The following steps must be completed before using the symptom table.

Visual/Physical Inspection

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for
Intermittent Conditions and Poor Connections
.

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom:

Bluetooth Malfunction

No Global Positioning System (GPS) Reception

OnStar Microphone Malfunction

OnStar Audio Malfunction

OnStar Button LED Malfunction

OnStar Call Center Remote Function Requests Malfunction

OnStar Button Malfunction

Unable to Contact OnStar Call Center

OnStar Voice Recognition Malfunction

OnStar Steering Wheel Control Functions Malfunction

SYMPTOMS - ENTERTAINMENT

IMPORTANT: The following steps must be completed before using the symptom table.

Visual/Physical Inspection

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for
Intermittent Conditions and Poor Connections
.

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom:

Application Malfunction

Auxiliary Audio Input Malfunction

Bluetooth Malfunction

Digital Radio Poor or No Reception

Navigation System - Voice Recognition Malfunction

No Global Positioning System (GPS) Reception

Radio Poor Reception

Speaker Malfunction

APPLICATION MALFUNCTION

Diagnostic Instructions

Circuit/System Description

The term application refers to any piece of software that works on a system (hardware) that is being operated by it's
own software. Applications are typically small software programs which uses the hardware to perform a specific
task, as opposed to operating the entire system.

Diagnostic Aids

When a mobile device is connected via BluetoothA®, some or all of the device controls may be unavailable
from the radio controls. This varies dependant upon the device being used. Refer to the vehicle owners
manual, supplements, and the device manufacturers information for information on devices, control, and
operation.

Refer to the device manufacturers information for the preferred connection method.

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Install or update the application on the device.

Refer to the application website

• If the radio calibrations are not current

Reprogram the radio and re-evaluate the concern.

Install or update the application on the radio.

Refer to diagnostic aids.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Refer to Control Module References for radio replacement, setup, and programming

AUXILIARY AUDIO INPUT MALFUNCTION

Diagnostic Instructions

DTC Descriptor

DTC B124B

USB 1 Circuit

For symptom byte information refer to Symptom Byte List .

Diagnostic Fault Information

| Circuit | Short to | Open/High | Short to | Signal |

Ground

Resistance

Voltage

Performance

B+

B124B, 2

B124B, 1

-

-

USB Cable

B124B

B124B

B124B

-

Ground

-

1

-

-

  • 1. Fault may affect one or more components, dependant on fault location

  • 2. Fault affects multiple components, dependant on vehicle equipment

Circuit/System Description

The infotainment system has a USB port and a Auxiliary Audio Input Jack located in the center console. The
receptacle assembly receives fused battery voltage and ground from the harness to power the internal hub device as
well as providing additional amperage to power USB devices.

The internal hub device interfaces directly with the human machine interface control module via a standard USB
cable. A Mini type USB connector is used to connect the human machine interface control module and the USB
receptacle. Standard USB male to female connections are typically used for connecting USB cables together where
an in-line connection is required. An in-line cable connection is typically found between the console and I/P harness.

Auxiliary Audio Input Jack

When a portable audio playback device is connected to the 3.5 mm (1/8 in.) auxiliary audio input jack an internal
switch opens the detection signal circuit within the hub. The HMI detects the device and AUX becomes available as
an audio source. Audio signals from the device are converted from analog to digital, these signals are then sent to the
HMI from the auxiliary input jack via USB.

USB Port

The USB port allows connectivity to the infotainment system from portable media players or a USB storage device
(memory stick/flash drive). When a device is connected to the USB port, the system detects the device and switches
to USB as the audio source. Once connected, the device can be controlled from the radio controls.

Not all portable media player devices or file types are compatible. Refer to the owner's manual for information on
USB devices, control, and operation.

Conditions for Running the DTC

Conditions for Setting the DTC

B124B 0B

The human machine interface control module detects an excessive current condition on the USB 5 V circuit.

B124B 04

The human machine interface control module does not detect the vehicle hub device.

B124B 11

The human machine interface control module detects an additional hub device attached to the vehicle USB port.

Action Taken When the DTC Sets

The USB port is inoperative while the DTC is current.

Conditions for Clearing the DTC

Diagnostic Aids

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Special Tools

Circuit/System Verification

• If DTC B124B is set.

Refer to Circuit/System Testing.

Refer to Circuit/System Testing

Refer to Circuit/System Testing

Refer to Circuit/System Testing

Circuit/System Testing

Perform the appropriate repair or replacement to correct any issues.

• If audio is not heard from the test tool, replace the K74 Human Machine Interface Control
Module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

BLUETOOTH MALFUNCTION

Diagnostic Instructions

Circuit/System Description

BluetoothA® wireless technology is a short-range communications technology intended to replace the cables
connecting portable and/or fixed devices while maintaining high levels of security. The operating range of the signal
is approximately 30 feet.

The available features and functions are determined by the type of device and the software within the devices being
used. For a feature or function to operate, it must be supported in both devices.

The BluetoothA® hardware is internal to the radio. The radio supports streaming of data (music, voice, information)
from cellular phones and other mobile devices that support those features. The radio may also be capable of
interfacing with cellular phones for hands-free features.

Refer to the vehicle owners manual, supplements, and the device manufacturers information for information on
devices, control, operation. and pairing instructions.

Diagnostic Aids

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Special Tools

EL-50334-20 Multi-Media Interface Tester (MIT)

Circuit/System Verification

Refer to Diagnostic Trouble Code (DTC) List - Vehicle .

Reprogram the radio and re-evaluate the concern.

NOTE: The MIT tool can be used to test either cellular phone or streaming audio
functions. Refer to the tool instructions, and perform the appropriate test(s)
related to the customers concern in the following steps.

Replace the A11 radio.

Replace the A11 radio.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to Control Module References for radio replacement, programming, and setup.

DIGITAL RADIO POOR OR NO RECEPTION

Diagnostic Instructions

DTC Descriptors

DTC B125C 01

Satellite Antenna Circuit Short to Battery

DTC B125C 02

Satellite Antenna Circuit Short to Ground

DTC B125C 04

Satellite Antenna Circuit Open

Circuit/System Description

The digital radio receiver, located inside the radio, receives digital radio information from the digital radio antenna
located on the outside of the vehicle. The digital radio receiver is connected to the digital radio antenna via a shielded
coax cable. The digital radio antenna contains an amplifier which is powered by the radio through the coax cable.

Conditions for Running the DTC

This DTC is run every 300 milliseconds.

Conditions for Setting the DTC

The radio detects a circuit fault in the digital radio antenna.

Action Taken When the DTC Sets

The radio displays No XM Signal or Check Antenna.

Conditions for Clearing the DTC

Diagnostic Aids

The digital radio antenna requires a clear line of sight to the sky to operate properly. Reception may be limited,
intermittent, or unavailable inside structures.

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Special Tools

EL-48028 Digital Radio Test Antenna

Circuit/System Verification

Refer to Circuit/System Testing.

Circuit/System Testing

Replace the A11 Radio.

Replace the antenna coax cable

Component Testing

CAUTION: Refer to Test Probe Caution .

NOTE: Before testing the coax cable, check the cable exterior for being pinched, cut,

damaged, or having loose connections at the components, which can cause
reception issues.

To prevent false reading when testing the center coax terminals, use care not to
ground the test probe on the outer housing/shield.

Coax Cable Test

Replace the coax cable

Replace the coax cable

Replace the coax cable

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

ONSTAR MICROPHONE MALFUNCTION

Diagnostic Instructions

The telematics communication interface control module provides the Cellular Phone Microphone with a supplied
voltage on the cellular phone microphone signal circuit. When the cellular phone microphone is in use, voice data
from the user is sent back to the telematics communication interface control module on the signal circuit.

Reference Information

Schematic Reference

OnStar/Telematics Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

OnStar Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

NOTE: It is necessary to have the vehicle in a quiet, open outside area where a cellular call
can be successfully placed and GPS data can be received from satellites.

• If DTC B2455 is set

Refer to DTC B2455.

Refer to Circuit/System Testing - Microphone Malfunction.

Refer to Circuit/System Testing - Cellular Telephone Voice Malfunction.

Circuit/System Testing

Microphone Malfunction

Cellular Telephone Voice Malfunction

Repair the short to voltage in the circuit.

Repair the short to ground on the circuit.

Repair the open/high resistance in the circuit.

Replace the A11 Radio.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair procedure.

NAVIGATION SYSTEM - VOICE RECOGNITION MALFUNCTION

Diagnostic Instructions

When voice recognition for the navigation equipped infotainment system is started, voice signals from the cellular
phone microphone are passed through the telematics communication interface control module to the radio via the
voice recognition audio circuits.

Diagnostic Aids

Reference Information

Schematic Reference

OnStar/Telematics Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Refer to OnStar Voice Recognition Malfunction.

NOTE: Refer to the Navigation System Owners Manual for voice recognition use and
commands.

Circuit/System Testing

Repair the short to voltage on the circuit.

Repair the short to ground on the circuit.

Repair the open/high resistance in the circuit.

NOTE: Refer to the Navigation System Owners Manual for voice recognition use and
commands.

• If the infotainment system does not respond correctly to any commands, replace the K73
Telematics Communication Interface Control Module.

• If the infotainment system responds correctly to the command

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to Control Module References for radio or telematics communication interface control module replacement,
programming, and setup.

ONSTAR AUDIO MALFUNCTION

Diagnostic Instructions

When an OnStarA® keypress is made, a serial data message is sent to the audio system to mute all radio functions
and output OnStarA® originated audio. After the audio system is muted, the telematics communication interface
control module transmits signals to the audio system on the audio signal and audio common circuits.

Reference Information

Schematic Reference

OnStar/Telematics Schematics

Radio/Navigation System Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

OnStar Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Refer to Speaker Malfunction

Refer to Circuit/System Testing

Circuit/System Testing

Repair the short to voltage on the circuit.

Repair the short to ground on the circuit.

Radio signal circuit terminal 19 X1

Repair the open/high resistance in the circuit.

Replace the A11 Radio.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to Control Module References for module replacement, programming, and setup.

NO GLOBAL POSITIONING SYSTEM (GPS) RECEPTION

Diagnostic Instructions

DTC Descriptors

DTC B2462 02

Global Positioning System Short to Ground

DTC B2462 04

Global Positioning System Open

Circuit/System Description

The navigation antenna is connected to the Telematics Communication Interface Control Module. The module
supplies 5 V to the antenna to power the internal amplifier through the center conductor of the antenna coax cable.

When the vehicle is equipped with the optional navigation system, a Navigation Antenna Signal Splitter is installed
to distribute the navigation signal to both the Telematics Communication Interface Control Module and the Human
Machine Interface Control Module. The Human Machine Interface Control Module supplies 5 V through the coax
cable to power the Navigation Antenna Signal Splitter.

Conditions for Running the DTC

Conditions for Setting the DTC

B2462 02

The Telematics Communication Interface Control Module or Human Machine Interface Control Module detects a
short to ground on the GPS antenna signal circuit.

B2462 04

The Telematics Communication Interface Control Module or Human Machine Interface Control Module detects a
open/high resistance on the GPS antenna signal circuit.

Action Taken When the DTC Sets

Conditions for Clearing the DTC

Diagnostic Aids

Reference Information

Schematic Reference

OnStar/Telematics Schematics

Radio/Navigation System Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

OnStar Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Special Tools

EL-49903 OnStar Antenna Diagnostic Tool Kit

Circuit/System Verification

NOTE: The following verification requires the vehicle to be outside with an unobstructed
view of the southern sky. Allow 5 minutes after turning the ignition ON for the
vehicle to acquire the GPS satellites signal.

Refer to Circuit/System Testing Without Navigation System.

Refer to Circuit/System Testing With Navigation System.

Refer to Circuit/System Testing Without Navigation System

Refer to Circuit/System Testing With Navigation System.

Refer to Circuit/System Testing With Navigation System - Step 9.

Refer to Circuit/System Testing With Navigation System - Step 9.

Circuit/System Testing

without Navigation System

NOTE: You must perform the Circuit/System Verification before proceeding with
Circuit/System Testing.

Replace the K73 Telematics Communication Interface Control Module.

Replace the coax cable.

with Navigation System

NOTE: You must perform the Circuit/System Verification before proceeding with
Circuit/System Testing.

Replace the coax cable.

Replace the K73 Telematics Communication Interface Control Module.

Replace the coax cable.

Replace the K74 Human Machine Interface Control Module

Replace the coax cable.

• If the coax cable passes the test.

Component Testing

CAUTION: Refer to Test Probe Caution .

NOTE:

  • • Before testing the coax cable, check the cable exterior for being pinched, cut,
    damaged, or having loose connections at the components, which can cause
    reception issues.

  • • To prevent false reading when testing the center coax terminals, use care not
    to ground the test probe on the outer housing/shield.

  • • The vehicle may be equipped with sectioned coax. Test each section and
    replace only the faulty section, not the entire length of coax.

Coax Cable Test

Replace the coax cable.

Replace the coax cable.

Replace the coax cable.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

ONSTAR BUTTON LED MALFUNCTION

Diagnostic Instructions

The OnStarA® status LEDs are located with the OnStar buttons. The green LED is illuminated when the system is
ON and operating normally. When the green LED is green and flashing, it is an indication that a call is in progress.
When the red LED is illuminated, a system malfunction is present. In the event there is a system malfunction and the
OnStarA® system is still able to make a call, the LED will flash red during the call. The OnStarA® LEDs are
controlled by the telematics communication interface control module via the keypad green LED signal circuit and the
keypad red LED signal circuit.

Reference Information

Schematic Reference

OnStar/Telematics Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

OnStar Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

NOTE:

If the green LED is off with the ignition ON and the LED does not function
when commanded with the scan tool, contact the OnStar Center to confirm the
vehicle has a current subscription.

Refer to Diagnostic Trouble Code (DTC) List - Vehicle

Refer to Circuit/System Testing - Green LED Test

Refer to Circuit/System Testing - Red LED Test

Circuit/System Testing

Green LED Test

Red LED Test

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair procedure.

ONSTAR CALL CENTER REMOTE FUNCTION REQUESTS MALFUNCTION

Diagnostic Instructions

Circuit/System Description

The telematics communication interface control module has the capability of commanding the horn, initiating door
lock/unlock, or operating the exterior lamps using the serial data circuits. These functions are commanded by the
OnStarA® Call Center per a customer request.

Diagnostic Aids

The customer concern may have been due to a lack of cellular service in a given area, or a failure in the National
Cellular Network infrastructure that has since been corrected.

Reference Information

Schematic Reference

OnStar/Telematics Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

OnStar Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

NOTE:

  • • It is necessary to inform the OnStarA® Call Center advisor that this call is for
    vehicle diagnostic purposes.

  • • It is necessary to have the vehicle in an open outside area where a cellular call
    can be successfully placed and GPS data can be received from satellites.

Refer to Diagnostic System Check - Vehicle .

Refer to Unable to Contact OnStar Call Center

Replace the K73 telematics communication interface control module

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to Control Module References for telematics communication interface control module replacement,
programming and setup.

ONSTAR BUTTON MALFUNCTION

Diagnostic Instructions

The OnStarA® button assembly consists of 3 buttons, Call/Answer, OnStarA® Call Center, and OnStarA®
Emergency. The telematics communication interface control module supplies the OnStarA® button assembly with 10
V via the keypad supply voltage circuit. Each of the buttons, when pressed, completes the circuit across a resistor
allowing a specific voltage to be returned to the telematics communication interface control module over the keypad
signal circuit. Depending upon the voltage range returned, the telematics communication interface control module is
able to identify which button has been activated.

Reference Information

Schematic Reference

OnStar/Telematics Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

NOTE: Contact the OnStarA® Call Center first before pressing the emergency button in
order to notify them of the test.

• If any DTCs are set

Refer to Diagnostic Trouble Code (DTC) List - Vehicle

Refer to Circuit System Testing.

Test or replace the S48B Multifunction Switch - Overhead Console.

Circuit/System Testing

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair procedure.

ONSTAR STEERING WHEEL CONTROL FUNCTIONS MALFUNCTION

Some vehicles equipped with the OnStarA® system have the capability of accessing voice mailboxes and other
automated phone systems by means of the steering wheel controls, while the OnStarA® Personal Calling feature is
in use. If the "Talk" or "Mute" button (depending upon the vehicle) on the steering wheel controls is depressed
during an OnStarA® Personal Calling call, the telematics communication interface control module receives the
message on the serial data bus from either the radio or body control module. This message is interpreted as a request
to turn any spoken numbers into dual tone multi-frequency tones to be delivered over the airwaves to the phone
system the user is communicating with. Complete instructions for operation of these features can be found in the
information provided to the customer with the OnStarA® system.

The steering wheel controls are a resistor network that consist of multiple momentary contact switches and a series
of resistors. The switches and resistor network are arranged so that each switch has a different resistance value.
When a switch is pressed, a voltage drop occurs in the resistor network, which produces a specific voltage value
unique to the switch selected, to be interpreted by either the radio or BCM. In the event the OnStarA® steering
wheel control functions are inoperative, technicians should refer to
Steering Wheel Controls Malfunction , to begin
diagnosis of the steering wheel control concern.

RADIO POOR RECEPTION

Diagnostic Instructions

DTC Descriptors

DTC B125A 02

Antenna Signal Circuit Short to Ground

DTC B125A 04

Antenna Signal Circuit Open Circuit

DTC B125A 01

Antenna Signal Circuit Short to Battery

Diagnostic Fault Information

Circuit

Short to
Ground

Open/High

Resistance

Short to
Voltage

Signal
Performance

Radio Antenna Coax

B125A 02

B125A 04

B125A 01

-

Circuit/System Description

The radio antenna for AM and FM radio reception is connected to the radio with a coaxial cable.

Conditions for Running the DTC

Conditions for Setting the DTC

B125A 02

The radio detects a short to ground in the antenna signal circuit center conductor.

B125A 04

The radio detects an open in the antenna signal circuit center conductor.

B125A 01

The radio detects a short to battery in the antenna signal circuit center conductor.

Action Taken When the DTC Sets

Radio reception may be poor or not available.

Conditions for Clearing the DTC

Diagnostic Aids

Poor AM and FM radio reception is dependent on multiple influences, some of which may not be vehicle related.
Areas which have high RF traffic or block the signal path may cause a degradation in radio reception. Radio
reception may also be influenced by items within the vehicle, but are not part of the radio system. Such examples are
aftermarket electrical accessories or other items which may generate noise in the vehicle electrical system.

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Repair or replace as necessary

Refer to Circuit/System Testing

Circuit/System Testing

Replace the antenna coax cable

Replace the radio antenna base.

Component Testing

CAUTION: Refer to Test Probe Caution .

NOTE: Before testing the coax cable, check the cable exterior for being pinched, cut,
damaged, or having loose connections at the components, which can cause
reception issues.

To prevent false reading when testing the center coax terminals, use care not to
ground the test probe on the outer housing/shield.

Coax Cable Test

Replace the coax cable

Replace the coax cable

Replace the coax cable

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

SPEAKER REPLACEMENT REFERENCE

Component

Repair Instruction

Front Center Speaker

Radio Front Center Speaker Replacement

Front Tweeter Speakers

Radio Front Speaker Replacement

Front Door Speakers

Radio Front Side Door Speaker Replacement

Rear Door Speakers

Radio Rear Side Door Speaker Replacement

Rear Subwoofer

Radio Rear Compartment Speaker Replacement

SPEAKER MALFUNCTION

Diagnostic Instructions

Each of the audio output channel circuits (+) and (-), at the radio and audio amplifier (if equipped) have a DC bias
voltage that is approximately one half of battery voltage. When using a DMM, each of the audio output channel
circuits will measure approximately 6.5 V DC. The audio being played on the system is produced by a varying AC
voltage that is centered around the DC bias voltage on the same circuit. The AC voltage is what causes the speaker
cone to move and produce sound. The frequency (Hz) of the AC voltage signal is directly related to the frequency of
the input (audio source playing) to the audio system. Both the DC bias voltage and the AC voltage signals are needed
for the audio system to properly produce sound.

Diagnostic Aids

The EL-50334-6 Audio System Diagnostic CD contains audio tracks that can be used to duplicate and isolate
such concerns. Tracks 11 and 12 contain audio sweep tones for testing for speaker and grill rattles.

If the speaker or surrounding interior trim is found to be loose or improperly secured, correctly secure the item.

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Special Tools

EL-50334-50 USB Cable and Adapter Kit

Circuit/System Verification

Without Amplifier

Radio ON, Mute OFF, verify clear audio is heard from each audio speaker.

With Amplifier

Radio ON, Mute OFF, verify clear audio is heard from each audio speaker.

Circuit/System Testing

Speaker Malfunction - without Amplifier

NOTE: In the following tests, audio signal frequencies (Hz) will be tested. To prevent
misdiagnosis, the door chime must be OFF during testing. Ensure the driver
door latch is closed during testing.

• If less than 5 V

Replace the A11 Radio.

Speaker Malfunction- with Amplifier

Replace the A11 Radio.

Replace the A11 Radio.

NOTE: In the following tests, audio signal frequencies (Hz) will be tested. To prevent
misdiagnosis, the door chime must be OFF during testing. Ensure the driver
door latch is closed during testing.

Replace the T3 Audio Amplifier.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

UNABLE TO CONTACT ONSTAR CALL CENTER

Diagnostic Instructions

DTC Descriptors

DTC B2470 02

Cellular Phone Antenna Circuit Malfunction Short to Ground

DTC B2470 04

Cellular Phone Antenna Circuit Malfunction Open Circuit

Circuit/System Description

The primary cellular phone antenna element is connected to the telematics communication interface control module
(violet connector) via a shielded coaxial cable. Cellular communication takes place on both the primary cellular
antenna signal circuit and the GPS/secondary cellular antenna signal circuit. This diagnostic only applies to the
primary cellular antenna signal circuit. Internal to the antenna on the cellular antenna signal circuit resistance is used
to apply a load, which the telematics communication interface control module uses to detect the presence of the
antenna.

Conditions for Running the DTC

Conditions for Setting the DTC

B2470 02

The telematics communication interface control module detects a short to ground on the primary cellular antenna
signal circuit.

B2470 04

Action Taken When the DTC Sets

The OnStarA® status LED turns red.

Conditions for Clearing the DTC

• A history DTC clears after 50 malfunction-free ignition cycles.

Reference Information

Schematic Reference

OnStar/Telematics Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

OnStar Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Special Tools

EL-49903-1 Test Antenna Navn-Cell Comn

Circuit/System Testing

NOTE:

  • • The vehicle may be equipped with sectioned coax. Test each section and
    replace only the faulty section, not the entire length of coax.

  • • The following verification requires the vehicle to be outside with an
    unobstructed view of the southern sky. Allow 5 min after turning the ignition
    ON for the GPS satellites to acquire vehicle signal.

• If the DTC sets or a call can not be completed to the OnStar Call Center

Replace the K73 Telematics Communications Interface Control Module.

Replace the coax cable.

Component Testing

CAUTION: Refer to Test Probe Caution

NOTE:

  • • Before testing the coax cable, check the cable exterior for being pinched, cut,
    damaged, or having loose connections at the components, which can cause
    reception issues.

  • • To prevent false readings when testing the center coax terminals, use care not
    to ground the test probe on the outer housing/shield.

Coax Cable Test

Replace the coax cable.

Replace the coax cable.

Replace the coax cable.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair procedure.

• Refer to High Frequency Antenna Replacement

ONSTAR VOICE RECOGNITION MALFUNCTION

Diagnostic Instructions

Circuit/System Description

The telematics communication interface control module is capable of interpreting voice commands received over the
cellular microphone circuits. Speech recognition allows the user to speak to one computer in the vehicle, and one
reached over the cellular communication network. The module attempts to understand the users command, and
responds by speaking back, or by taking the appropriate action, e.g. dialing the phone.

Reference Information

Schematic Reference

OnStar/Telematics Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

OnStar Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Circuit/System Verification

NOTE:

  • • It is necessary to have the vehicle in an open outside area where a cellular call
    can be successfully placed and GPS data can be received from satellites.

  • • The vehicle should be located in a quiet area.

• If your voice can not be heard clearly

Refer to OnStar Microphone Malfunction

Replace the K73 Telematics Communication Interface Control Module

Refer to OnStar Description and Operation for tips on proper pronunciation

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair procedure.

Refer to Control Module References for telematics communication interface control module replacement,
programming and setup

VOICE RECOGNITION MALFUNCTION

Diagnostic Instructions

When voice recognition for the infotainment system is started, voice signals from the cellular phone microphone are
passed through the telematics communication interface control module to the Human Machine Interface Control
Module via the voice recognition audio circuits.

Diagnostic Aids

• Background noise such as a climate control fan positioned on high, open windows, or very loud outside noises,
can cause voice commands to be misunderstood.

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Refer to OnStar Voice Recognition Malfunction.

NOTE: Refer to the Owners Manual and/or the Navigation System Owners Manual for
voice recognition use and commands.

commands.

Circuit/System Testing

Repair the short to voltage on the circuit.

Repair the short to ground on the circuit.

Repair the open/high resistance in the circuit.

NOTE: Refer to the Owners Manual and/or the Navigation System Owners Manual for
voice recognition use and commands.

• If the infotainment system does not respond correctly to any commands, replace the K73
Telematics Communication Interface Control Module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to Control Module References for Human Machine Interface Control Module or Telematics Communication
Interface Control replacement, programming and setup.

REPAIR INSTRUCTIONS

MOBILE TELEPHONE MICROPHONE REPLACEMENT

Fig. 9: Mobile Telephone Microphone

Courtesy of GENERAL MOTORS COMPANY

Callout

Component Name

Callout

Component Name

Preliminary Procedure

Remove Roof Console. Refer to Roof Console Replacement

1

Mobile Telephone Microphone

Procedure

Release the retaining tabs.

MOBILE TELEPHONE ANTENNA CABLE REPLACEMENT

Fig. 10: Mobile Telephone Antenna Cable
Courtesy of GENERAL MOTORS COMPANY

Callout

Component Name

Preliminary Procedure

Remove Instrument Panel Assembly. Refer to Instrument Panel Assembly Replacement

1

Mobile Telephone Antenna Cable

Procedure

  • 1. Disconnect all electrical connectors.

  • 2. If the cable is taped into the wiring harness, cut the ends off the old cable and route the
    new cable as close to the old one as possible. Use tie straps to secure the new cable.

HUMAN MACHINE INTERFACE CONTROL MODULE REPLACEMENT

Fig. 11: Human Machine Interface Control Module
Courtesy of GENERAL MOTORS COMPANY

Callout

Component Name

Preliminary Procedure

Remove Instrument Panel Center Air Outlet. Refer to Instrument Panel Center Air Outlet Replacement

1

Human Machine Interface Control Module

Procedure

  • 1. Disconnect all electrical connectors.

  • 2. Release the retaining tabs.

  • 3. Refer to Control Module References for programming and set up procedures, if required.

COMMUNICATION INTERFACE MODULE REPLACEMENT

Fig. 12: Communication Interface Module
Courtesy of GENERAL MOTORS COMPANY

Callout

Component Name

Communication Interface Module

Procedure

1

  • 1. Disconnect the electrical connectors.

  • 2. Push the retaining tabs outward and slide the module downward.

  • 3. Perform the necessary programming and setup procedure: Control Module References

COMMUNICATION INTERFACE MODULE BATTERY REPLACEMENT

Fig. 13: Communication Interface Module Battery
Courtesy of GENERAL MOTORS COMPANY

Callout

Component Name

Preliminary Procedure

Remove Communication Interface Module Bracket. Refer to Communication Interface Module Bracket

Replacement

1

Communication Interface Module Battery

Procedure

  • 1. Push the retaining tab outward and slide the module downward.

  • 2. Refer to Control Module References for programming and setup information, if required.

COMMUNICATION INTERFACE MODULE BRACKET REPLACEMENT

Fig. 14: Communication Interface Module Bracket
Courtesy of GENERAL MOTORS COMPANY

Callout

Component Name

Preliminary Procedure

Remove Instrument Panel Assembly. Refer to Instrument Panel Assembly Replacement

1

Communication Interface Module Bracket Bolt (Qty: 3)

CAUTION:

Refer to
Fastener

Caution .

Tighten

2.5 N.m (22 lb in)

2

Communication Interface Module Bracket

Procedure

  • 1. Disconnect all electrical connectors.

  • 2. Transfer components as necessary.

RADIO REPLACEMENT

Fig. 15: Radio

Courtesy of GENERAL MOTORS COMPANY

Callout

Component Name

Preliminary Procedure

Remove Radio Speaker Amplifier. Refer to Radio Speaker Amplifier Replacement

1

Radio

Procedure

  • 1. Release the retaining tabs.

  • 2. Disconnect all electrical connectors.

  • 3. Refer to Control Module References for programming and setup information, if
    required.

RADIO CONTROL ASSEMBLY REPLACEMENT

Fig. 16: Radio Control Assembly

Courtesy of GENERAL MOTORS COMPANY

Callout

Component Name

Preliminary Procedure

Remove Instrument Panel Center Air Outlet. Refer to Instrument Panel Center Air Outlet Replacement

1

Radio Control Bolt (Qty: 4)

CAUTION:

Refer to
Fastener

Caution .

Tighten

2.5 N.m (22 lb in)

2

Radio Control

Procedure

  • 1. Transfer components as necessary.

  • 2. Refer to Control Module References for programming and setup procedures, if required.

AUDIO DISC PLAYER AND USB RECEPTACLE REPLACEMENT

Fig. 17: Audio Disc Player And USB Receptacle
Courtesy of GENERAL MOTORS COMPANY

Callout

Component Name

Preliminary Procedure

Remove Front Floor Console. Refer to Front Floor Console Replacement

1

Audio Disc Player and USB Receptacle

Procedure

  • 1. Depress the tabs on the receptacle to remove.

  • 2. Disconnect the electrical connector.

RADIO SPEAKER AMPLIFIER REPLACEMENT

Fig. 18: Radio Speaker Amplifier

Courtesy of GENERAL MOTORS COMPANY

Callout

Component Name

Preliminary Procedure

Remove Radio Rear Compartment Speaker. Refer to Radio Rear Compartment Speaker Replacement

1

Radio Speaker Amplifier Bracket Bolt (Qty: 3)

CAUTION:

Refer to
Fastener

Caution .

Tighten

9 N.m (80 lb in)

2

Radio Speaker Amplifier

Procedure

  • 1. Disconnect all electrical connectors.

  • 2. Refer to Control Module References for programming and setup information, if required.

NAVIGATION SIGNAL SPLITTER REPLACEMENT

Fig. 19: Navigation Signal Splitter

Courtesy of GENERAL MOTORS COMPANY

Callout

Component Name

Preliminary Procedure

Remove Communication Interface Module Bracket. Refer to Communication Interface Module Bracket

Replacement

1

Navigation Signal Splitter

Procedure

Release the retaining tabs.

TELEVISION ANTENNA CABLE REPLACEMENT

Fig. 20: Television Antenna Cable

Courtesy of GENERAL MOTORS COMPANY

Callout

Component Name

Preliminary Procedure

  • 1. Remove Human Machine Interface Control Module. Refer to Human Machine Interface Control

Module Replacement

  • 2. Remove Instrument Panel Lower Center Trim Panel. Refer to Instrument Panel Lower Center Trim
    Panel Replacement (Upper) Instrument Panel Lower Center Trim Panel Replacement (Lower)

1

Television Antenna Cable

Procedure

  • 1. Disconnect the electrical connectors.

  • 2. If the cable is taped into the wiring harness, cut the ends off the old cable and route the
    new cable as close to the old one as possible. Use tie straps to secure the new cable.

MOBILE TELEPHONE ANTENNA COAXIAL CABLE REPLACEMENT

Fig. 21: Mobile Telephone Antenna Coaxial Cable
Courtesy of GENERAL MOTORS COMPANY

Callout

Component Name

Preliminary Procedure

Remove Headlining Trim Panel. Refer to Headlining Trim Panel Replacement

1

Mobile Telephone Antenna Coaxial Cable

Procedure

  • 1. Disconnect the electrical connectors.

  • 2. Reposition the front floor panel carpet as necessary.

  • 3. If the cable is taped into the wiring harness, cut the ends off the old cable and route the
    new cable as close to the old one as possible. Use tie straps to secure the new cable.

RADIO ANTENNA CABLE REPLACEMENT

Fig. 22: Radio Antenna Cable

Courtesy of GENERAL MOTORS COMPANY

Callout

Component Name

Preliminary Procedure

  • 1. Remove Headlining Trim Panel. Refer to Headlining Trim Panel Replacement

  • 2. Remove Quarter Lower Rear Trim Panel (Right Side). Refer to Quarter Lower Rear Trim Panel

Replacement (Right Side)

1

Radio Antenna Cable

Procedure

  • 1. Disconnect the electrical connectors.

  • 2. If the cable is taped into the wiring harness, cut the ends off the old cable and route the
    new cable as close to the old one as possible. Use tie straps to secure the new cable.

Harness Routing Views

NAVIGATION ANTENNA COAXIAL CABLE REPLACEMENT (INLINE TO ONSTAR TO SPLITTER)

Fig. 23: Navigation Antenna Coaxial Cable (Inline To Onstar To Splitter)
Courtesy of GENERAL MOTORS COMPANY

Callout

Component Name

Preliminary Procedure

Remove Instrument Panel Assembly. Refer to Instrument Panel Assembly Replacement

1

Navigation Antenna Coaxial Cable

Procedure

  • 1. Disconnect all electrical connectors.

  • 2. If the cable is taped into the wiring harness, cut the ends off the old cable and route the
    new cable as close to the old one as possible. Use tie straps to secure the new cable.

NAVIGATION ANTENNA COAXIAL CABLE REPLACEMENT (ONSTAR TO SPLITTER)

Fig. 24: Navigation Antenna Coaxial Cable (Onstar To Splitter)
Courtesy of GENERAL MOTORS COMPANY

Callout

Component Name

Preliminary Procedure

Remove Instrument Panel Knee Bolster. Refer to Instrument Panel Knee Bolster Replacement

1

Navigation Antenna Coaxial Cable

Procedure

  • 1. Disconnect all electrical connectors.

  • 2. If the cable is taped into the wiring harness, cut the ends off the old cable and route the
    new cable as close to the old one as possible. Use tie straps to secure the new cable.

NAVIGATION ANTENNA COAXIAL CABLE REPLACEMENT (SPLITTER TO HMI)

Fig. 25: Navigation Antenna Coaxial Cable (Splitter To HMI)
Courtesy of GENERAL MOTORS COMPANY

Callout

Component Name

Preliminary Procedure

  • 1. Remove Heater and Air Conditioning Remote Control. Refer to Heater and Air Conditioning Remote

Control Replacement

  • 2. Remove Instrument Cluster. Refer to Instrument Cluster Replacement

1

Navigation Antenna Coaxial Cable

Procedure

  • 1. Disconnect all electrical connectors.

  • 2. If the cable is taped into the wiring harness, cut the ends off the old cable and route the
    new cable as close to the old one as possible. Use tie straps to secure the new cable.

RADIO FRONT CENTER SPEAKER REPLACEMENT

Fig. 26: Radio Front Center Speaker

Courtesy of GENERAL MOTORS COMPANY

Callout

Component Name

Preliminary Procedure

Remove Instrument Panel Extension. Refer to Instrument Panel Extension Replacement

1

Radio Front Center Speaker Bolt (Qty: 2)

CAUTION:

Refer to
Fastener

Caution .

Tighten

2.5 N.m (22 lb in)

2

Radio Front Center Speaker

Procedure

Disconnect the electrical connector.

RADIO FRONT SPEAKER REPLACEMENT

Fig. 27: Radio Front Speaker

Courtesy of GENERAL MOTORS COMPANY

Callout

Component Name

Preliminary Procedure

Remove Instrument Panel Extension. Refer to Instrument Panel Extension Replacement

1

Radio Front Speaker Bolt (Qty: 4)

CAUTION:

Refer to
Fastener

Caution .

Tighten

2.5 N.m (22 lb in)

2

Radio Front Speaker

Procedure

Disconnect the electrical connector.

HIGH FREQUENCY ANTENNA REPLACEMENT

Fig. 28: High Frequency Antenna

Courtesy of GENERAL MOTORS COMPANY

Callout

Component Name

Preliminary Procedure

Remove Headlining Trim Panel. Refer to Headlining Trim Panel Replacement

1

High Frequency Antenna Nut

CAUTION:

Refer to
Fastener

Caution .

Tighten

9 N.m (80 lb in)

2

High Frequency Antenna

Procedure

Disconnect the electrical connectors.

RADIO FRONT SIDE DOOR SPEAKER REPLACEMENT

Fig. 29: Radio Front Side Door Speaker

Courtesy of GENERAL MOTORS COMPANY

Callout

Component Name

Preliminary Procedure

Remove Front Side Door Trim. Refer to Front Side Door Trim Replacement

1

Radio Front Side Door Speaker Fastener

CAUTION:

Refer to
Fastener

Caution .

Tighten

2.5 N.m (22 lb in)

2

Radio Front Side Door Speaker

Procedure

  • 1. Disconnect the electrical connector.

  • 2. Unclip and reposition the wiring harness.

RADIO CONTROL SWITCH REPLACEMENT - STEERING WHEEL (LEFT SIDE REAR)

Fig. 30: Radio Control Switch - Steering Wheel (Left Side Rear)
Courtesy of GENERAL MOTORS COMPANY

Callout

Component Name

Preliminary Procedure

Remove Steering Wheel Spoke Cover. Refer to Steering Wheel Spoke Cover Replacement

1

Radio Control Switch Bolt

CAUTION:

Refer to
Fastener

Caution .

Tighten

2.5 N.m (22 lb in)

2

Radio Control Switch - Left Side Rear

Procedure

Disconnect the electrical connector.

RADIO CONTROL SWITCH REPLACEMENT - STEERING WHEEL (RIGHT SIDE REAR)

Fig. 31: Radio Control Switch - Steering Wheel (Right Side Rear)
Courtesy of GENERAL MOTORS COMPANY

Callout

Component Name

Preliminary Procedure

Remove Steering Wheel Spoke Cover. Refer to Steering Wheel Spoke Cover Replacement

1

Radio Control Switch Bolt

CAUTION:

Refer to
Fastener

Caution .

Tighten

2.5 N.m (22 lb in)

2

Radio Control Switch - Right Side Rear

Procedure

Disconnect the electrical connector.

RADIO CONTROL SWITCH REPLACEMENT - STEERING WHEEL (RIGHT SIDE FRONT)

Fig. 32: Radio Control Switch - Steering Wheel (Right Side Front)
Courtesy of GENERAL MOTORS COMPANY

Callout

Component Name

Preliminary Procedure

Remove Steering Wheel Spoke Cover. Refer to Steering Wheel Spoke Cover Replacement

1

Radio Control Switch Bolt (Qty: 2)

CAUTION:

Refer to
Fastener

Caution .

Tighten

1.5 N.m (13 lb in)

2

Radio Control Switch - Right Side Front

Procedure

Remove the radio control switch from the steering wheel spoke cover.

RADIO CONTROL SWITCH REPLACEMENT - STEERING WHEEL (LEFT SIDE LOWER)

Removal Procedure

1. Remove Steering Wheel Spoke Cover. Refer to Steering Wheel Spoke Cover Replacement

Fig. 33: Steering Wheel Spoke Lower Cover
Courtesy of GENERAL MOTORS COMPANY

Installation Procedure

Fig. 35: Radio Control Switch And Bolts

Courtesy of GENERAL MOTORS COMPANY

CAUTION: Refer to Fastener Caution .

RADIO REAR SIDE DOOR SPEAKER REPLACEMENT

Fig. 37: Radio Rear Side Door Speaker

Courtesy of GENERAL MOTORS COMPANY

Callout

Component Name

Preliminary Procedure

Remove Rear Side Door Trim. Refer to Rear Side Door Trim Replacement

1

Radio Rear Side Door Speaker Fastener

CAUTION:

Refer to
Fastener

Caution .

Tighten

2.5 N.m (22 lb in)

2

Radio Rear Side Door Speaker

Procedure

Disconnect the electrical connector.

RADIO REAR COMPARTMENT SPEAKER REPLACEMENT

Fig. 38: Radio Rear Compartment Speaker
Courtesy of GENERAL MOTORS COMPANY

Callout

Component Name

Preliminary Procedure

Remove Quarter Lower Rear Trim Panel (Right Side). Refer to Quarter Lower Rear Trim Panel

Replacement (Right Side)

1

Radio Rear Compartment Speaker Fastener (Qty: 3)

CAUTION:

Refer to
Fastener

Caution .

Tighten

6 N.m (53 lb in)

2

Radio Rear Compartment Speaker

Procedure

  • 1. Unclip the wiring harness.

  • 2. Disconnect the electrical connector.

  • 3. Transfer components as necessary.

DESCRIPTION AND OPERATION

ONSTAR DESCRIPTION AND OPERATION

This OnStarA® system consists of the following components:

This system also interfaces with the factory installed vehicle audio system.

1 C3

■ Telematics

Communication

I Interface

"I B24

■ Cellular

1 Phone

I Microphone

1 S51

I Telematics

1 Button

I Assembly

1 T4G

■ Cellular

’ Phone.

I Navigation.


I Telematics
Communication

I Interface

Control Module


Fig. 39: OnStar System Block Diagram

Courtesy of GENERAL MOTORS COMPANY

Callout

Component Name

Callout

Component Name

B24

B24 Cellular Phone Microphone

C3

C3 Telematics Communication Interface Control Module Battery

S51

S51 Telematics Button Assembly

T4G

T4G Cellular Phone, Navigation, and Digital Radio Antenna

T4S

T4S Wireless Communication Antenna - Bluetooth

K73

K73 Telematics Communication Interface Control Module

A11

A11 Radio

X84

X84 Data Link Connector

Telematics Communication Interface Control Module

The OnStar Generation 10 system uses Global System for Mobile Communication (GSM) to communicate data and
voice signals over the national cellular network. The module may also have the ability to act as a Wireless Local
Area Network (WLAN) Wi-Fi hotspot similar to a home wireless router. The module houses an internal WLAN
antenna enabling hotspot connectivity and streaming high speed media to the entertainment system. The module also
may enable Teletypewriter (TTY) and be capable of Bluetooth communication utilizing an internal antenna. The
module is capable of up to 4G LTE speeds and houses 2 technology systems, one to process Global Positioning
System (GPS) data, and another for cellular information. The module sends and receives all cellular communications
over two cellular antennas and cellular antenna coax cables.

The OnStar Gen 10 system has two antenna inputs, a primary cellular signal and a combined GPS/secondary cellular
signal. The OnStarA® system uses the United States Global Positioning System (GPS) signals to provide location on
demand. GPS is a space-based satellite navigation system that provides location and time information in all weather
conditions, anywhere on or near Earth where there is an unobstructed line of sight to four or more GPS satellites.

The module also has the capability of activating certain features such as, the horn, remote starting, initiating door
lock/unlock, or activating the exterior lamps using the serial data circuits. These functions can be commanded by the
OnStarA® Call Center per a customer request or mobile device app depending on vehicle and customer subscription.

Dedicated circuits are used to connect the telematics communication interface control module to a microphone, the
button assembly, radio, and if equipped the Back Up Battery (BUB). The telematics communication interface control
module communicates with the rest of the vehicle over the serial data bus.

Power is provided by a dedicated, fused B+ circuit. Ground is provided through the vehicle wiring harness attached
to the module. The power mode state is determined by the telematics communication interface control module
through serial data messaging.

OnStarA® Three Button Assembly

• The OnStarA® button assembly may be part of the rearview mirror, or a separate, stand alone unit. The button
assembly is comprised of 3 buttons or 3 capacitive touch buttons and status LED's or an error indicator. The
buttons are defined as follows:

If the LED does not illuminate, this may indicate that the customers OnStarA® subscription is not active or has
expired. Push the blue OnStar button to connect to an advisor who can then verify the account status.

The telematics communication interface control module supplies 10 volts to the OnStarA® button assembly on the
keypad supply voltage circuit. When pressed, each button completes a circuit across a resistor allowing a specific
voltage to be returned to the telematics communication interface control module on the keypad signal circuit.
Depending upon the voltage range returned the telematics communication interface control module is able to identify
which button has been pressed.

The OnStarA® status LED or error indicator is located near the buttons. The LED is green when the system is ON
and operating normally. When any indicator is illuminated and flashing, it is an indication that a call is in progress.
When the LED is red, this indicates a system malfunction is present. In the event there is a system malfunction and
the OnStarA® system is still able to make a call, the LED will flash red during the call.

Each LED or error indicator is controlled by either the telematics communication interface control module over
dedicated LED signal circuits or by low speed GMLAN serial data depending on the inside rearview mirror option.
Ground for the LED is provided by the wiring harness attached to the button assembly.

Secondary OnStarA® Controls

Some vehicles may have an additional button that when pushed can engage the OnStarA® system. The button may
be a symbol of a face with sound waves, or may say MUTE, or be a symbol of a radio speaker with a slash through
it.

By engaging the OnStarA® system with this feature, the user can interact with the system by use of voice
commands. A complete list of these commands is supplied in the information provided to the customer. If the
information is not available for reference, at any command prompt the user can say "HELP" and the telematics
communication interface control module will return an audible list of available commands.

OnStarA® Microphone

The cellular microphone can be part of the rearview mirror assembly, or a stand-alone unit in the headliner or roof
console. In either case, the telematics communication interface control module supplies approximately 10V to the
microphone on the cellular microphone signal circuit. The microphone modifies the 10V depending on the volume
and voice being detected. A cellular microphone low reference circuit or a drain wire provides a ground for the
microphone. The microphone signal circuits pass through the telematics communication interface control module to
support entertainment voice recognition.

Cellular and GPS Antennas

The combination antenna will have any of the following antenna elements when equipped with OnStar:

The Gen 10 OnStarA® system uses 2 cellular antenna elements to send and receive cellular data, the primary cellular
element and the secondary cellular element. The primary cellular signal is carried by a coax cable that connects the
antenna directly to the telematics communication interface control module. Details of the secondary cellular signal
are further described below.

The GPS antenna element is used to collect the signals of the orbiting GPS satellites. Within the antenna is housed a
low noise amplifier that allows for a more broad and precise reception of this data. Also housed within the antenna is
circuitry to combine the GPS signal and the secondary cellular signal. Without navigation, the combination
GPS/secondary cellular signal is carried by a coax cable that connects directly to the telematics communication
interface control module. The cable also provides a path for DC current for powering the antenna. With navigation,
the combination GPS/secondary cellular signal is carried by a coax cable that connects to the navigation signal
splitter. The splitter supplies the GPS signal to the navigation/entertainment system and the GPS/cellular signal to the
telematics communication interface control module.

The digital radio element collects digital radio signals from two satellites and where necessary terrestrial repeaters.
The digital radio signal is carried by a coax cable and connected to the digital radio receiver. Refer to Radio/Audio
System Description and Operation for further details.

The radio signal is sent from a broadcast station and is then received by the AM/FM radio antenna element. The
AM/FM radio signal is carried by a coax cable and is connected to the radio. Refer to Radio/Audio System
Description and Operation for further details.

OnStarA® RemoteLink

OnStarA® RemoteLink is a mobile app to link mobile devices to a vehicle for limited diagnostics and feature
controls. After downloading the app and registering the device, vehicle owners with an eligible vehicle can use their
mobile devices to access real-time data from their vehicle and perform specific commands remotely.

All communication between the app and the vehicle is powered by OnStar'sA® advanced connected vehicle
technology. An active OnStarA® account as well as a valid OnStarA® username and password are required to use
the app. The remote commands must be enabled by logging into the user's OnStarA® account prior to using the app.
Refer to the owners manual for available vehicle data and control features.

Compass Heading

The telematics communication interface module has a compass feature to calculate vehicle direction which is
displayed via the instrument panel cluster or designated display. The compass heading is determined by dead
reckoning until the GPS 3d fix is established. The dead reckoning is accomplished by using the yaw rate sensors and
wheel ticks to determine heading changes from a GPS known heading. The GPS 3d fix heading is determined by the
deferential of two locations. If "CAL" is displayed on the Instrument Panel Cluster or designated display refer to the
owners manual for steps to calibrate the compass.

BluetoothA® (If Equipped)

BluetoothA® wireless technology is a short-range communications technology intended to replace the cables
connecting portable and/or fixed devices while maintaining high levels of security. Only vehicles with steering wheel
controls will have BluetoothA® functionality. In order to utilize the vehicle's BluetoothA® system, a BluetoothA®
equipped cellular phone is required.

The BluetoothA® antenna is internal to the telematics communication interface control module, radio or human
machine interface module and is used to send and receive signals from a BluetoothA® enabled cellular phone. The
available features and functions are determined by the software within the device being used and the telematics
communication interface control module. The operating range of the signal from the vehicle is approximately 30
feet. Note that the operating range is dependent upon the cellular phone being used and battery level of the phone.

With BluetoothA® technology customers can experience hands-free calling as their BluetoothA® capable cellular
phones are wirelessly connected to the vehicle. It will allow customers to place and receive calls using the steering
wheel controls and voice recognition. The vehicle audio system will allow you to listen to your call through the
vehicle speakers and adjust volume through steering wheel or radio controls.

Not all BluetoothA® cellular phones are guaranteed to work with the vehicle's BluetoothA® system. Based on the
cellular phone's service provider and the manufacturer's implementation of BluetoothA®, not all phones support all
available BluetoothA® functionality. BluetoothA® enabled cellular phones will be tested for vehicle compatibility
and a feature compatibility list will be provided via the GM BluetoothA® website:
http://www.gm.com/vc/bluetooth/

BluetoothA® Features Supported

The following is a list of features supported by the BluetoothA® system. Note that not all devices will support all of
the listed functions.

Pairing a BluetoothA® Cellular Phone to the Vehicle

In order to use hands-free calling, the cellular phone must be paired to the vehicle. Up to five devices can be paired
to the vehicle at one time, but only one can be connected at any given time. To pair a phone, the customer must know
how to operate the BluetoothA® functionality of their phone. The pairing process must only be done one time for
each phone, unless that phone's information is deleted. The system will always generate a password and will provide
that password if the device you are pairing does not support Secure Simple Pairing (SSP). If the device being paired
does support SSP the system will not provide the password and automatically pair the device. For safety reasons, the
pairing process is disabled while the vehicle is moving.

Once the BluetoothA® cellular phone has been paired with vehicle, it will automatically connect to the vehicle when
the ignition is on and the device is on. When more than one paired phone is in the vehicle, the phone with the highest
priority will be connected. If the cellular phone is in use while getting into the vehicle, the phone can be switched to
hands-free mode with the press of a button. In addition, a call in progress can be transferred from the vehicle hands-
free mode to the phone to continue the call as the customer exits the vehicle.

Complete pairing instructions are provided in the Vehicle Owners Manual.

Back-up Battery (If Equipped)

NOTE: Do not disconnect the main vehicle battery or remove the OnStarA® fuse with the
ignition key in any position other than OFF. Disconnecting power to the OnStarA®
module in any way while the ignition is ON or with retained accessory power
activated may cause activation of the OnStarA® Back-Up Battery. This action is per
design as the back-up battery is designed to provide power to the telematics
communication interface control module so an emergency notification call can be
made after an event where the main battery is disabled. Once the Back-Up Battery is
activated it will stay on until the power is restored back to the telematics
communication interface control module. The telematics communication interface
control module naturally chooses the main supply voltage as it's default supply, but
if the main supply is removed or lost for any reason the OnStarA® module will use
the Back-Up Battery as a power supply as long as the default supply can not be
detected. The back-up battery is not rechargeable and once discharged below 9.5
volts the back-up battery must be replaced.

Certain OnStarA® equipped vehicles may also be equipped with a back-up battery. The back-up battery is a non-
rechargeable, lithium battery intended to provide an auxiliary power source for the telematics communication
interface control module in the event where power from the main vehicle battery is lost.

The back-up battery is intended to have a limited life span of approximately 4 years and is designed to maintain an
open circuit voltage between 16 V and 9 V throughout this period. This allows the battery to power the basic
functions of the telematics communication interface control module for least one 200 second (5 minute) call at the
end of the 4 year span, should the main vehicle battery be lost. In the case of a vehicle losing vehicle battery power,
OnStar will switch over to the backup battery based on an internal algorithm. It will look for an air-bag deploy, or
near-deploy, messages from the SDM. If there are no messages the OnStar module will stay wake for a few minutes
longer and monitor the buttons in the mirror. If not pressed, the modules will power down and shut off completely.

The back-up battery is connected to the telematics communication interface control module through the back-up
battery positive voltage circuit and back-up battery ground circuit and is protected from a short circuit by means of
an internal fuse. In the event the back-up battery, battery positive voltage circuit is shorted to the back-up battery
ground circuit or chassis ground, the fuse will open and render the back-up battery permanently inoperable. The
status of the back-up battery and its associated wiring is monitored by the telematics communication interface
control module.

WiFi Hotspot

The telematics communication interface control module acts as a Wireless Local Area Network (WLAN) WiFi
hotspot router and uses direct 4G LTE connectivity to the internet. It has the ability to connect up to 7 devices at one
time. A data plan is required and when purchased, a security default password is established. There are several ways
to change the SSID or password, by placing a call to the OnStar Call Center, by using the Gen 10 mobile app or
through the scan tool.

The system utilizes a secure autoconnect feature between the telematics communication interface control module and
the radio/HMI. No user interaction is required, it is always available and ready to connect to a dedicated in car
device. The ignition must be in Run, Accessory or RAP for WiFi to operate.

Audio System Interface

When the OnStarA® requires audio output, a serial data message is sent to the audio system to mute all radio
functions and transmit OnStarA® originated audio. The OnStarA® audio is transmitted to the vehicle audio system
by a dedicated signal circuit and a low reference circuit.

The audio system will mute and an audible ring will be heard though the speakers if the vehicle receives a call with
the radio ON.

On some vehicles, the HVAC blower speed may be reduced when the OnStarA® system is active to aid in reducing
interior noise. When the system is no longer active, the blower speed will return to its previous setting.

OnStarA® Sleep Cycle

The OnStarA® system uses a unique sleep cycle to allow the system to receive cellular calls while the ignition is in
the OFF position and retained accessory power mode has ended. This cycle enables the telematics communication
interface control module to perform remote functions, such as door unlock, as commanded over the air by the
OnStarA® Call Center, and to continue to maintain an acceptable level of battery electrical drain.

The OnStarA® system uses 4 states of readiness, depending upon the type of cellular market the vehicle is in when
the ignition is put into the OFF state:

The high power state is in effect whenever the ignition is in the ON or RUN position, or retained accessory power is
enabled, and the OnStarA® system is sending or receiving calls or when the system is performing a remote function.

The low power state is in effect when the OnStarA® system is idle with the ignition in the ON or RUN position, or
with retained accessory power enabled.

The sleep state is entered after the vehicle has been shut off and the retained accessory power has timed out while in
an analog cellular area. At a predetermined time recorded within the telematics communication interface control
module, the system re-enters the low power state to listen for a call from the OnStarA® Call Center for 1 minute.
After this interval, the system will again return to the sleep state for 9 minutes. If a call is sent during the 1 minute
interval, the OnStarA® system will receive the call and immediately go into the high power mode to perform any
requested functions. If no call is received during the 1 minute interval, the system will go back into the sleep mode
for another 9 minutes. This process will continue for up to 48 hours, after which the OnStarA® system will turn off
until the ignition is turned to the ON or RUN position.

The digital standby power state is entered after the vehicle has been shut off and the retained accessory power has
timed out while in a digital cellular area. When in digital standby mode, the OnStarA® module is able to perform all
remote functions as commanded by an OnStarA® advisor at any time, for a continuous 120 hours. After 120 hours,
the OnStarA® module will go into sleep mode until a wake up signal from the vehicle is seen by the telematics
communication interface control module. If the OnStar module loses the digital cellular signal it will revert to analog
mode and follow the standard sleep state (9 minutes OFF, 1 minute standby) based on the time of the GPS signals,
this will continue until a digital cellular signal is again received.

If the OnStarA® system loses battery power while the system is in a standby or sleep mode, the system will remain
OFF until battery power is restored and the ignition is turned to the ON or RUN position.

Features

OnStarA® Personal Calling

The hands free, OnStarA® personal calling cellular phone feature is an additional feature of the OnStarA® system.
This feature is embedded within the telematics communication interface control module; however it must be
activated by an OnStarA® advisor. OnStarA® personal calling operates similar to most hand held cellular phones in
that the availability for its usage is based on minutes or units. The customer must have a current OnStarA®
subscription, as this feature cannot be utilized without it. To use OnStarA® personal calling, the customer must also
purchase units (minutes) as outlined in the owners guide provided with the OnStarA® system. Units begin to deplete,
1 unit is equal to 1 minute, as the customer makes outbound phone calls, answers inbound phone calls, or while
connected to the OnStarA® virtual advisor. In addition, units may also have an expiration date, depending upon the
type of units purchased.

Customers have the ability to store telephone numbers within the module, referenced by a nametag for the
convenience of frequently dialed numbers. After storing a nametag, the user can dial this number by initiating the
OnStarA® personal calling feature, speaking the word "call," and repeating the nametag assigned.

Turn by Turn Navigation

Turn by Turn Navigation allows the driver to contact OnStarA® to obtain directions for driving from a current
location to a desired location. The Turn by Turn Navigation system stores your planned route and continually checks
your position along that route, when you deviate from the planned route, the system will recognize this and prompt
the driver with verbal prompts for how to proceed. The driver then responds verbally to direct the system to continue
the current routing or to recalculate the route because of a missed turn.

Advisor Record Feature

The Advisor Record Feature allows the user to store any information given during a call with an OnStarA® Advisor.
Recording is activated by pressing the blue OnStar button during a call; pressing the button a second time stops the
recording. The stored information can be played back by pressing the phone button on the three button assembly and
using the voice command "Advisor Playback".

Teletypewriter (TTY) Users

OnStar has the ability to communicate to deaf, hard-of-hearing, or speech-impaired customers while in the vehicle.
The available dealer-installed TTY system can provide in-vehicle access to all of the OnStar services, except Virtual
Advisor and OnStar Turn-by-Turn Navigation.

Deactivated OnStarA® Accounts

In the event a customer has not renewed their OnStarA® account after expiration or the account was never activated,
OnStarA® will make a discrete cellular call to the vehicle to deactivate the OnStarA® system. Before taking this
action, customers are notified that the OnStarA® system in their vehicle will be deactivated unless they elect to
renew the account. After the OnStarA® account has been deactivated, customers will experience the following:

Certain vehicles that have never had an active OnStarA® account, or that have been deactivated, may be unable to
establish a connection with the OnStarA® Call Center. When normal published diagnostic procedures do not indicate
a possible cause for the no connect concern, the vehicle may have been deactivated. For deactivated vehicles, a no
connect response should be considered normal operation. Further diagnosis and subsequent repair is only necessary
should the customer elect to become an active OnStarA® subscriber or renew the account subscription.

OnStarA® Cellular, GPS, and Diagnostic Limitations

The proper operation of the OnStarA® System is dependent on several elements outside the components integrated
into the vehicle. These include the National Cellular Network Infrastructure, the cellular telephone carriers within the
network, and the GPS.

The cellular operation of the OnStarA® system may be inhibited by factors such as the users range from an analog or
digital cellular tower, the state of the cellular carrier's equipment, and the location where the call is placed. Making
an OnStarA® key press in areas that lack sufficient cellular coverage or have a temporary equipment failure will
result in either the inability of a call to complete with a data transfer or the complete inability to connect to the
OnStarA® Call Center. The OnStarA® system may also experience connection issues if the identification numbers
for the module, station identification number, electronic serial number or manufacturers electronic ID, are not
recognized by the cellular carriers local signal receiving towers.

The satellites that orbit earth providing the OnStar system with GPS data have almost no failures associated with
them. In the event of a no GPS concern, the failure will likely lie with the inability of the system to gain GPS signals
because of its location, i.e. in a parking structure, hardware failure, or being mistaken with an OnStarA® call which
has reached the Call Center without vehicle data.

During diagnostic testing of the OnStarA® system, the technician should ensure the vehicle is located in an area that
has a clear unobstructed view of the open sky, and preferably, an area where analog or digital cellular calls have been
successfully placed. These areas can be found by successfully making an OnStarA® keypress in a known good
OnStarA® equipped vehicle and confirming success with the OnStarA® Call Center advisor. Such places can be
used as a permanent reference for future OnStarA® testing.

Mobile Identification Number and Mobile Directory Number

The telematics communication interface control module utilizes 2 numbers for cellular device identification, call
routing and connection, a mobile identification number and a mobile directory number. The mobile identification
number represents the number used by the cellular carrier for call routing purposes while the mobile directory
number represents the number dialed to reach the cellular device.

Operation of the OnStarA® Speech Recognition Systems

OnStarA® users communicate with 2 speech recognition systems. Speech recognition allows the user to speak to one
computer in the vehicle, and one reached over a phone line. The computer tries to understand the users command,
and responds by speaking back, or by taking the appropriate action, e.g. dialing the phone.

The OnStarA® speech recognition systems use speech technology that is designed to understand a wide range of
American English speakers. Although there is no one right way to speak English, the system will work best when
users try to modify their pronunciation should they encounter difficulty. Users who do not obtain good results are
advised to try the tips and workarounds found in the Infotainment System Manual or the Owners Manual.

RADIO/AUDIO SYSTEM DESCRIPTION AND OPERATION

The entertainment system on this vehicle may have several different configurations available to it. To determine the
specific configuration of the vehicle, please see the Service Parts ID Label, and refer to
RPO Code List .

Each item in the list below represents topics covered in detail below.

Radio Circuit Operation

Radio Power

The radio does not use a discrete ignition feed circuit for power moding. The power mode master provides the
system power mode to the radio via serial data messages. The power mode master determines the system power
mode by processing power mode information from ignition switch inputs. Serial data power modes supported by the
radio are OFF, ACCESSORY, RUN, and CRANK REQUEST.

Radio Grounds

The vehicle harness provides a ground for the radio circuits. The radio may also be case grounded.

Radio Data Link Communication

The radio communicates with other modules via serial data.

Radio Audio Outputs

Each of the audio output channel circuits (+) and (-), at the radio have a DC bias voltage that is approximately one
half of battery voltage. The audio being played on the system is produced by a varying AC voltage that is centered
around the DC bias voltage on the same circuit. The AC voltage is what causes the speaker cone to move and
produce sound. The frequency (Hz) of the AC voltage signal is directly related to the frequency of the input (audio
source playing) to the audio system. Both the DC bias voltage and the AC voltage signals are needed for the audio
system to properly produce sound.

Remote Enable Output

The remote enable circuit is a discrete 12 V signal supplied to infotainment system components when the radio is
producing audio, needs the front display on, needs video entertainment system components on, or needs to produce
chimes. This signal is used to control the power state of the components. There is no output on radio the remote
enable circuit when the vehicle is in the CRANK powermode, this is to minimize current consumption from the
attached modules and also to avoid audio pops during crank events.

Information Display and Controls

Fig. 40: Navigation Radio Communications Flow Diagram
Courtesy of GENERAL MOTORS COMPANY

Callout

Component Name

1

Radio/HVAC Controls

2

Info Display Module

3

Radio

4

HVAC Control Module

5

Data Link Connector

a

GMLAN

b

Local Interconnect Network

c

CAN Graphical Interface

d

Digital Video

e

Touch Screen Serial Data

The info display module has continuous power and ground. When the radio is on, a discrete 12 V signal is supplied
on the remote enable circuit to the color display module. This signal is used to control the power state of the module,
which is active when the signal is high and inactive when the signal is low.

The info display module receives digital video data from the radio for on-screen display information through a
dedicated video cable. The radio communicates with the info display module over the touch screen serial data
circuits for touch screen inputs and backlighting dimming level.

The radio controls communicate radio control inputs directly to the radio through the CAN Graphical Interface (CGI)
data circuits. After receiving the message the radio will perform the requested function. Messages communicated
between the radio and the radio/HVAC controls include the following:

The HVAC controls are a separate component from the radio controls. HVAC data for controls and status indicators
is communicated between the HVAC controls and the HVAC control module with a separate LIN serial data circuit.
HVAC status screen information from the HVAC control module is transmitted to the radio on the GMLAN serial
data circuit. The radio then displays the desired screen information on the info display using the video data circuits.

Antenna System

The multi-band antenna is located on the roof of the vehicle. This type of antenna may be used with the AM/FM
radio, but is primarily for OnStarA® cellular and GPS signals and the XM™ Satellite Radio Service System, if the
vehicle has these features. Keep this antenna clear of snow and ice build up for clear reception. If the vehicle has a
sunroof, the performance of the system may be affected if the sunroof is open. Loading items onto the roof of the
vehicle can interfere with the performance of the system, ensure the multi-band antenna is not obstructed.

The radio provides battery voltage to the AM/FM amplifier in the antenna base using the center conductor of the
antenna coaxial cable. When a 12 V signal is seen by the amplifier, both AM and FM signals are amplified.

Radio Reception

AM/FM Radio Signal

The radio signal is sent from a broadcast station and is then received by an antenna. The strength of the signal
received depends on the following:

Digital Radio Receiver (If equipped)

The XM satellite receiver is integrated into the radio. XM satellite radio provides digital radio reception. The XM
signal is broadcast from two satellites and, where necessary, terrestrial repeaters. The high power satellites allow the
antenna to receive the XM signal even when foliage and other partial obstructions block the antennas view of the
satellite. Terrestrial repeaters are used in dense urban areas. These repeaters will receive the satellite signal and re-
broadcast them at much higher power levels in order to ensure reception in areas with densely packed tall buildings.
A service fee is required in order to receive the XM service.

Radio Data System (RDS)

The RDS feature is available only on FM stations that broadcast RDS information. This system relies upon receiving
specific information from these stations and only works when the information is available. While the radio is tuned
to an FM-RDS station, the station name or call letters display. RDS data is carried in what is known as a "subcarrier".
A subcarrier is a frequency that the FM broadcaster is authorized to use to send data that is not audible in the main
audio program.

RDS functions will only work with FM broadcast stations that are broadcasting RDS data. Not all FM Broadcast
stations broadcast RDS data or offer all of the RDS services.

The information displayed is dependent upon the information broadcast by the particular station. The information
may vary greatly between stations. RDS functions may not work properly when reception is weak, reception is of
poor quality, or RDS is not implemented properly by the FM Broadcaster. In some cases, a radio station broadcasting
incorrect information may cause the RDS features of the radio to appear to work improperly.

With RDS, the radio can do the following:

Speaker Operation

Speakers turn electrical energy into mechanical energy to move air, using a permanent magnet and an electromagnet.
The electromagnet is energized when the radio or amplifier (if equipped) delivers current to the voice coil on the
speaker. The voice coil will form a north and south pole that will cause the voice coil and the speaker cone to move
in relation to the permanent magnet. The current delivered to the speaker is rapidly changing alternating current
(A/C). This causes the speaker cone to move in two directions producing sound.

Audio Amplifier (If equipped)

Amplifier Interface

A fused battery voltage circuit provides the main amplifier power. A switched 12 V output from the radio is used to
control the power - state of the amplifier. To respond quickly to audio input and control signals, the amplifier is ON
in all vehicle power modes except OFF and CRANK Request. The internal amplifier bridges are fully powered and
unmuted when the amplifier receives the switched 12 V input.

Amplifier Operation

The purpose of the amplifier is to increase the power of a voltage or current signal. The output signal of an amplifier
may consist of the same frequencies as the input signal or it may consist of only a portion of the frequencies as in the
case of a subwoofer or midrange speaker. The radio creates a low level stereo audio output signal, which is sent at
the user-defined volume level to the audio amplifier. The audio amplifier amplifies the signal and sends it to the
appropriate speakers. Each of the audio output channel circuits (+) and (-), from the amplifier have a DC bias voltage
that is approximately one half of battery voltage. The audio being played on the system is produced by a varying AC
voltage that is centered around the DC bias voltage on the same circuit. The AC voltage is what causes the speaker
cone to move and produce sound. The frequency (Hz) of the AC voltage signal is directly related to the frequency of
the input (audio source playing) to the audio system. Both the DC bias voltage and the AC voltage signals are needed
for the audio system to properly produce sound.

Theft Deterrent

The radio theft deterrent system is intended to disable or limit radio functionality if incorrect vehicle information is
received by the radio. The radio disables functionality if the VIN information received by the radio does not match
the VIN information that has been learned by the radio. The radio receives this information via serial data. A possible
cause of incorrect VIN info could be the radio was originally installed in another vehicle.

The radio has the following theft operating modes as part of the theft deterrent system:

Auxiliary Audio Input Jack (If equipped)

The infotainment system may have a 3.5 mm (1/8 in.) auxiliary audio input jack located in the center console. The
auxiliary audio input jack may interface directly with the radio, or be connected to the infotainment system via a
Multimedia Player Interface Module. When a portable audio playback device is connected to the auxiliary jack, an
internal switch detects the connection and the radio will switch to AUX as the audio source. Audio signals from the
device are sent to the radio from the auxiliary jack via the left, right, and common audio signal circuits.

USB Port (If Equipped)

The infotainment system may have a USB connector located in the center console. The USB connector may interface
directly with the radio, or be connected to the infotainment system via a Multimedia Player Interface Module. The
USB connector supports both USB standards 1.1 and 2.0.

USB Supported Devices:

Depending on the USB device, some devices may not be recognized, or some features/functions may not be able to
be controlled with the radio controls. USB HUB devices are not supported.

BluetoothA® (If Equipped)

BluetoothA® wireless technology is a short-range communications technology intended to replace the cables
connecting portable and/or fixed devices while maintaining high levels of security. The operating range of the signal
is approximately 30 feet.

The available features and functions are determined by the type of device and the software within the devices being
used. For a feature or function to operate, it must be supported in both devices.

The first connection between devices is established through a process called pairing. In order to pair two devices, a
password (passkey) has to be exchanged between the two devices. One device will generate the password, the other
device accepts the password to complete the process. Once the devices are paired, future connections between the
devices will occur automatically when the devices are on and within range of each other.

The BluetoothA® hardware is internal to the radio. The radio supports streaming of data (music, voice, information)
from cellular phones and other mobile devices that support those features. The radio may also be capable of
interfacing with cellular phones for hands-free features.

Refer to the vehicle owners manual, supplements, and the device manufacturers information for pairing instructions.

Applications (If equipped)

When the system is equipped with BluetoothA®, the system may be capable of using applications, commonly
referred to as apps.

The term application refers to any piece of software that works on a system (hardware) that is being operated by it's
own software. Applications are typically small software programs which uses the hardware to perform a specific
task, as opposed to operating the entire system.

Refer to the owner's manual and supplements for information on mobile devices, control, and operation.

Navigation System Components and Features (if equipped)

The navigation system, if equipped, provides the following:

Global Positioning System (GPS) Antenna

The global positioning system (GPS) antenna is part of the multi-band antenna located on the roof of the vehicle. The
GPS antenna is used to collect the signals of the orbiting GPS satellites. Within the antenna is housed a low noise
amplifier that allows for a more broad and precise reception of this data. The GPS antenna amplifier is powered
through the coaxial cable.

The antenna is connected to the navigation radio through a signal splitter. The signal splitter is a component for
dividing the navigation signal into two paths without any transmission loss. This allows the use of a single GPS
antenna to provide a signal to both the navigation radio and the telematics communication interface module.

Route Guidance

The map will display the route to the selected destination. Voice prompts alert the operator of upcoming events
(turns) and arrivals at the destination. The navigation system will automatically recalculate if the route is not
followed. The navigation radio uses data received from the global positioning system (GPS) satellites, the vehicle
speed signal. and serial data information to accurately display the current position of the vehicle.

Points of Interest

The map database provides point of interest information. Points of interests are locations that are frequently visited.
Points of interest can be can be displayed on the map or set as a destination. The following are some of the available
Points of interests:

Traffic Information

XM NavTraffic™ is a subscription based service that enhances the navigation system with live traffic information.
The service provides information on traffic conditions such as traffic speed, accidents, disabled vehicles,
construction and road closings.

The integrated XM satellite radio receives the information. When Traffic Information is turned ON in the
configuration menu, the available information will be displayed on the map screen.

The traffic information can vary based upon coverage in the area, and coverage is not available in all areas. No
information will be displayed if coverage is not available, if there is no traffic information for the area, or if there is
no subscription to receive the information.

A subscription fee is required in order to receive the XM NavTraffic™ service. No traffic data will be displayed
without a current subscription.

Weather Information

XM NavWeather™ is a subscription based service that transmits weather information to the integrated XM satellite
radio. Real time information such as current and future weather and road conditions, atmospheric conditions, and
National Weather Service warnings is provided, as well as 3 day forecasts for some cities. Received information is
available to be displayed on the Weather Info screen.

A subscription fee is required in order to receive the XM NavWeather™ service. No weather data will be displayed
without a current subscription.

OnStarA® (If equipped)

When OnStar is activated, a serial data message is sent to the radio that activates a software program. When the
software begins its process, the fade goes to the front, Bass and Treble are set to the mid range, the outputs are mono,
and the audio source is OnStar. OnStar takes priority over any other audio source. All of these actions are preset
values stored in the radio.

For additional OnStar information, refer to OnStar Description and Operation.

Steering Wheel Controls (If equipped)

Some audio functions are available using the steering wheel controls. The steering wheel controls duplicate the
function of the primary controls available on the radio.

For additional information on steering wheel controls, refer to Steering Wheel Controls Description and
Operation
.

Auto Volume Control

With auto volume control, the audio system will adjust automatically to make up for road and wind noise as you
drive, by increasing the volume as vehicle speed increases. To use auto volume control, set the volume at the desired
level, and then select either Low, Medium, or High. To turn auto volume control off, select the Off screen button.

SPECIAL TOOLS AND EQUIPMENT

SPECIAL TOOLS

Illustration

Tool

Number/Description

EL-50334-20
Multi-Media
Interface Tester
(MIT)

Illustration

Tool
Number/Description

EL-50334-50
USB Cable and
Adapter Kit

Illustration

Tool
Number/Description

EL-48028
Digital Radio Test
Antenna

Illustration

Tool
Number/Description

У

0^^

EL-49903-1

Test Antenna, Navn-
Cell Comn

EL-49903-2
Adapter Cable-UHF
RT Angle

EL-49903-3A
Combiner Kit, Test
Antenna

EL-50334-12
Infotainment Test
Cable - RSE

EL-50334-13
Infotainment Test
Cable - RSE Splitter

EL-50334-14
Infotainment Test
Cable

Illustration

Tool
Number/Description

EL-50334-15

Video Bypass Cable

SPECIAL TOOLS (MIT TOOL INSTRUCTIONS)

Bluetooth Pairing for Vehicles with Radio RPO: UF7

Either reset the pin code on the radio to 0000, or go under Device Info on the radio and see what the pin code is (to
enter it later on the MIT).

Make test call and the audio streaming test.

Holden Radio Bluetooth Pairing Instructions

For all other Radios

Testing the Bluetooth Function

Standard Bluetooth Pairing/Bonding

The vehicle should confirm pairing/bonding is complete.

Streaming Audio

To Place a Test Call

NOTE: If the call is not answered within several rings, the MIT's audio files will not
transmit, even though an active call is occurring.

NOTE: The MIT will remain paired/bonded when the call is ended by the vehicle. To re-
test the call function, place the MIT in Bluetooth mode and press and release
the Pair button to reconnect. When testing is completed, delete MIT from the
audio system before returning the vehicle to the customer.

Testing the AUX/Line-In Function

Testing the USB Function

NOTE: Volume levels may vary dependent upon vehicle audio system.

Troubleshooting Guide

If the MIT unit is still not working properly after following the below troubleshooting, the unit is malfunctioning and
should be repaired or replaced.

Unit not Working

Problem with Aux/Line-In Test

Problem with USB Test

Problem with Bluetooth Pairing

Problem with Bluetooth Test Call Audio

Article GUID: A00884689

ACCESSORIES & EQUIPMENT
Cruise Control - Volt

SPECIFICATIONS

FASTENER SPECIFICATIONS

Reusable Threaded Fastener Tightening Specifications_______________

NOTE:

All fasteners
listed in this
table can be
reused after
removal.

Application

Specification

Metric (English)

Steering Wheel Spoke Cover Fastener

1.5 N.m (13 lb in)

SCHEMATIC WIRING DIAGRAMS

CRUISE CONTROL WIRING SCHEMATICS

Cruise Control

Fig. 1: Cruise Control

Courtesy of GENERAL MOTORS COMPANY

DIAGNOSTIC INFORMATION AND PROCEDURES

DTC P0571: CRUISE CONTROL BRAKE SWITCH CIRCUIT

Diagnostic Instructions

DTC Descriptor

DTC P0571

Cruise Control Brake Switch Circuit

Circuit/System Description

The engine control module (ECM) monitors the brake pedal position sensor. When the brake pedal is applied,
the ECM detects a predetermined voltage signal. The ECM sends a serial data message to the body control
module (BCM) indicating the status of the stop lamps.

This diagnostic test functions on the assumption that a sudden decrease in vehicle speed is caused by a brake
pedal application. When the ECM detects that there is a 4.2 km/h (2.6 mph) or greater decrease in vehicle speed
within 0.25 s without a transition of the stop lamp switch, the ECM sets DTC P0571.

Conditions for Running the DTC

Conditions for Setting the DTC

The BCM detects either a low voltage signal on the stop lamp switch signal circuit when the serial data message
from the ECM indicates the brakes are applied, or a high voltage signal on the stop lamp switch signal circuit
when the serial data message from the ECM indicates the brakes are not applied.

Actions Taken When the DTC Sets

Conditions for Clearing the DTC

• A history DTC will clear after 40 malfunction-free ignition cycles have occurred.

Reference Information

Schematic Reference

Cruise Control Schematics

Exterior Lights Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Cruise Control Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Refer to Diagnostic Trouble Code (DTC) List - Vehicle

Refer to Diagnostic Trouble Code (DTC) List - Vehicle .

Replace the K9 Body Control Module.

• If the DTC does not set

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to Control Module References for BCM or ECM replacement, programming and setup.

DTC P0572 OR P0573: BRAKE SWITCH CIRCUIT 1 LOW/HIGH VOLTAGE

Diagnostic Instructions

DTC Descriptors

DTC P0572

Brake Switch Circuit 1 Low Voltage

DTC P0573

Brake Switch Circuit 1 High Voltage

Diagnostic Fault Information

Circuit

Short to
Ground

Open/High
Resistance

Short to
Voltage

Signal
Performance

Stop Lamp Switch Signal

C0297, P0572

P0572

P0573

P0703

Circuit/System Description

The brake pedal position sensor signal circuit is a B+ input from the body control module (BCM) to the engine
control module (ECM). The BCM and ECM monitor the brake pedal position sensor signal circuit to detect
when the brake pedal has been applied. When the brake pedal is applied, the BCM supplies B+ on the stop lamp
signal circuit and also sends a serial data message to the ECM indicating that the brake pedal has been applied.

Conditions for Running the DTC

Conditions for Setting the DTC

P0572

This DTC will set when the ECM detects a short to ground or an open on the discrete brake signal circuit when
the serial data message from the BCM indicates the brakes are applied. This diagnostic will run when the serial
data message and the voltage signal on the brake switch signal circuit do not match for 8 out 10 times, and the
condition is present for greater than 2 s.

P0573

This DTC will set when the ECM detects a short to voltage on the discrete brake signal circuit when the serial
data message from the BCM indicates the brakes are not applied. This diagnostic will run when the serial data
message and the voltage signal on the brake switch signal circuit do not match for 8 out 10 times, and the
condition is present for greater than 2 s.

Actions Taken When the DTC Sets

Conditions for Clearing the DTC

Reference Information

Schematic Reference

Cruise Control Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Cruise Control Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

set.

Refer to Diagnostic Trouble Code (DTC) List - Vehicle

Circuit/System Testing

NOTE: All components may need to be disconnected on the cruise control brake signal
circuit to isolate a short to voltage, short to ground or an open/high resistance
condition. Use the schematic to identify the proper brake signal terminal (circuit
6311) at the K20 Engine Control Module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to Control Module References for control module replacement, programming, and setup.

DTC P0575: CRUISE CONTROL SWITCH SIGNAL MESSAGE COUNTER INCORRECT

Diagnostic Instructions

DTC Descriptor

DTC P0575

Cruise Control Switch Signal Message Counter Incorrect

Circuit/System Description

When a cruise control function switch is activated, the body control module (BCM) detects a predetermined
voltage. The BCM sends a serial data message to the engine control module (ECM) indicating the function that
has been requested.

Conditions for Running the DTC

Conditions for Setting the DTC

Actions Taken When the DTC Sets

DTC P0575 is a type C DTC.

Conditions for Clearing the DTC

DTC P0575 is a type C DTC.

Reference Information

Schematic Reference

Cruise Control Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Cruise Control Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Refer to Diagnostic Trouble Code (DTC) List - Vehicle .

Replace the K20 Engine Control Module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to Control Module References for BCM or ECM replacement, programming, and setup.

DTC P0703: BRAKE SWITCH SIGNAL MESSAGE COUNTER INCORRECT

Diagnostic Instructions

DTC Descriptor

DTC P0703

Brake Switch Signal Message Counter Incorrect

Circuit/System Description

The body control module (BCM) monitors the brake pedal position sensor. When the brake pedal is applied, the
BCM detects a predetermined voltage signal. The BCM sends a serial data message to the engine control
module (ECM) indicating the status of the stop lamps.

Conditions for Running the DTC

The engine is ON.

Conditions for Setting the DTC

Actions Taken When the DTC Sets

Conditions for Clearing the DTC

Reference Information

Schematic Reference

Cruise Control Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Cruise Control Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

• If any other DTC is set, except DTC P0703

Refer to Diagnostic Trouble Code (DTC) List - Vehicle .

Replace the K20 Engine Control Module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to Control Module References for BCM or ECM replacement, programming, and setup.

DTC P158A: CRUISE CONTROL CALIBRATION INCORRECT

Diagnostic Instructions

DTC Descriptor

DTC P158A

Cruise Control Calibration Incorrect

Circuit/System Description

The type of cruise control system the vehicle has is programmed into the body control module and the engine
control module. If this information is not the same in both modules DTC P158A will set.

Conditions for Running the DTC

This diagnostic runs continuously.

Conditions for Setting the DTC

The type of cruise control system programmed into the body control module does not match what is
programmed into the engine control module.

Actions Taken When the DTC Sets

DTC P158A is a Type C DTC.

Conditions for Clearing the DTC

DTC P158A is a Type C DTC.

Reference Information

Schematic Reference

Cruise Control Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Cruise Control Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Refer to Diagnostic Trouble Code (DTC) List - Vehicle .

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to Control Module References for control module replacement, programming, and setup.

SYMPTOMS - CRUISE CONTROL

NOTE: The following steps must be completed before using the symptom tables.

Visual/Physical Inspection

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for
Intermittent Conditions and Poor Connections
.

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom:

Cruise Control Malfunction - DTC B3794, P0564, P0565, P0567, P0568, P056C, P0580, P0581,
P155A-P155C, or P162C

Cruise Control Indicator Malfunction

CRUISE CONTROL INDICATOR MALFUNCTION

Diagnostic Instructions

Circuit/System Description

The instrument cluster illuminates the cruise control engaged indicator based on serial data messages received
from the engine control module (ECM). The indicator is commanded ON when the cruise control system is
controlling vehicle speed, and turned OFF with the system disengaged.

Reference Information

Schematic Reference

Cruise Control Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Cruise Control Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Replace the P16 Instrument Cluster.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to Control Module References for instrument cluster replacement, programming and setup.

CRUISE CONTROL MALFUNCTION - DTC B3794, P0564, P0565, P0567, P0568, P056C, P0580,
P0581, P155A-P155C, OR P162C

Diagnostic Instructions

DTC Descriptors

DTC B3794

Cruise Control Function Request Circuit

DTC P0564

Cruise Control Multifunction Switch Circuit

DTC P0565

Cruise Control Switch Circuit

DTC P0567

Cruise Control Resume Switch Circuit

DTC P0568

Cruise Control Set Switch Circuit

DTC P056C

Cruise Control Cancel Switch Circuit

DTC P0580

Cruise Control Multifunction Switch Circuit Low Voltage

DTC P0581

Cruise Control Multifunction Switch Circuit High Voltage

DTC P155A

Cruise Control Switch State Undetermined

DTC P155B

Cruise Control Set/Coast Switch 2 Circuit

DTC P155C

Cruise Control Resume/Acceleration Switch 2 Circuit

DTC P162C

Vehicle Speed Limiting/Warning Switch Circuit

For symptom byte information, refer to Symptom Byte List .

Diagnostic Fault Information

Circuit

Short to
Ground

Open/High
Resistance

Short to
Voltage

Signal
Performance

Ignition

1

1

-

-

Circuit

Short to
Ground

Open/High
Resistance

Short to
Voltage

Signal
Performance

Signal

1

P0564

B3794 08,
P0567, P0568

B3794 61, P0564

1. Cruise Control Malfunction

Circuit/System Description

The cruise control switch is an input to the body control module (BCM). The BCM monitors the cruise control
on/off, set/coast, resume/accelerate and cancel switches via the cruise control switch signal circuit in order to
detect when the driver has requested to perform a cruise control function. The BCM detects a specific voltage
signal on the cruise control switch signal circuit when a switch is applied. The engine control module (ECM)
receives the requested cruise control switch function from the BCM via a serial data message.

Conditions for Running the DTC

Conditions for Setting the DTC

B3794 08

The BCM detects an invalid voltage signal on the cruise control switch signal circuit for 1 s.

B3794 61

Stuck switch for either Resume/Accel or Set/Coast button for 60 s.

P0564, P0565, P0567, P0568, P056C

P0580, P0581

P155A

The ECM is unable to determine the state of the cruise control switch.

P162C

The ECM is unable to determine the state of the vehicle speed limiting switch.

Actions Taken When the DTC Sets

B3794

P0564, P0565, P0567, P0568, P056C, P0580, P0581, P155A, P162C

DTCs P0564, P0565, P0567, P0568, P056C, P0580, P0581, P155A and P162C are type C DTCs

Conditions for Clearing the DTC

B3794

P0564, P0565, P0567, P0568, P056C, P0580, P0581, P155A, P162C

DTCs P0564, P0565, P0567, P0568, P056C, P0580, P0581, P155A and P162C are type C DTCs.

Reference Information

Schematic Reference

Cruise Control Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Cruise Control Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Refer to Diagnostic Trouble Code (DTC) List - Vehicle

Refer to Circuit/System Testing.

Repair the condition that is causing the inhibit reason.

Refer to Circuit/System Testing.

Ignition On/Vehicle in Service Mode.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to Control Module References for control module replacement, programming and setup.

REPAIR INSTRUCTIONS

CRUISE CONTROL SWITCH REPLACEMENT

Fig. 2: Cruise Control Switch

Courtesy of GENERAL MOTORS COMPANY

Callout

Component Name

Preliminary Procedure

Remove Steering Wheel Spoke Cover. Refer to Steering Wheel Spoke Cover Replacement

1

Steering Wheel Spoke Cover Fastener (Qty: 2)

CAUTION:

Refer to
Fastener

Caution .

Tighten

1.5 N.m (13 lb in)

2

Cruise Control Switch

Procedure

Remove the cruise control switch from the steering wheel spoke cover.

DESCRIPTION AND OPERATION

CRUISE CONTROL DESCRIPTION AND OPERATION

Switch -


Wheel


Fig. 3: Cruise Control System Block Diagram
Courtesy of GENERAL MOTORS COMPANY

Callout

Component Name

K20

K20 Engine Control Module

S70L

S70L Steering Wheel Controls Switch - Left

P16

P16 Instrument Cluster

K9

K9 Body Control Module

Cruise control is a speed control system that maintains a desired vehicle speed under normal driving conditions
at speeds above 40 km/h (25 mph). Steep grades may cause variations in the selected vehicle speeds.

The following are the main components of the Cruise Control System:

The body control module (BCM) monitors the signal circuit of the cruise control switches, which are located on
the steering wheel. The BCM relays the cruise control switch status to the engine control module (ECM) via the
serial data circuit. The ECM uses the status of the cruise control switch to determine when to capture and
maintain the vehicle speed. The ECM monitors the vehicle speed signal circuit in order to determine the desired
vehicle speed.

Voltage is supplied to the cruise control switch via the steering wheel control switch reference voltage circuit
supplied by the BCM. The cruise control function switches are arranged in a resistive ladder design, with each
cruise control function switch having a different resistance value. The BCM detects a specific voltage value that
is associated with the cruise control function switch being activated. The BCM sends a serial data message to
the ECM indicating that the on/off switch is active. Similarly, when the normally open + RES switch or the
normally open - SET switch are pressed, the switch closes and the BCM detects the predetermined voltage
signal on the cruise control resume/accel and set/coast switch signal circuit. The BCM sends a serial data
message to the ECM indicating that the + RES switch or the - SET switch is active.

Cruise Control Engaged

The Cruise Control System will engage and adjust vehicle speeds, based on the activation of the following
cruise control switches, which are located on the steering wheel:

To engage the Cruise Control System, ensure that the vehicle speed is above 40.2 km/h (25 mph), turn the cruise
On/Off switch ON and momentarily press the - SET switch. The ECM will engage the Cruise Control System
and record the vehicle speed. The ECM sends a serial data message to the instrument panel cluster (IPC) in
order to illuminate the Cruise Engaged indicator in the IPC. Refer to the vehicle owner's manual for the location
and operation of the cruise control On/Off indicators and driver information center (DIC) messages.

Pressing the accelerator pedal while the Cruise Control System is engaged, allows the driver to override the
Cruise Control System in order to accelerate the vehicle beyond the current set vehicle speed. When the
accelerator pedal is released, the vehicle will decelerate and resume the current set vehicle speed.

The driver can also override the current set vehicle speed via the - SET switch and the + RES switch. When the
Cruise Control System is engaged, pressing and holding the - SET switch will allow the vehicle to decelerate
from the current set vehicle speed without deactivating the Cruise Control System. When the - SET switch is
released, the ECM will record the vehicle speed and maintain the vehicle speed as the new set vehicle speed.
When the Cruise Control System is engaged, momentarily pressing the - SET switch will allow the vehicle to
decelerate at a vehicle specific calibratable increment, commonly 1 km/h or 1 mph, each time that the - SET is
momentarily pressed, with a minimum vehicle speed of 38 km/h (24 mph). Refer to the vehicle Owner's Manual
for more information.

Pressing and holding the + RES switch, when the Cruise Control System is engaged, will allow the vehicle to
accelerate to a greater vehicle speed than the current set vehicle speed. When the + RES switch is released, the
ECM will record the vehicle speed and maintain the vehicle speed as the new set vehicle speed. When the
Cruise Control System is engaged, momentarily pressing the + RES switch will allow the vehicle to accelerate
at a vehicle specific calibratable increment, commonly 1 km/h or 1 mph, each time that the + RES switch is
momentarily pressed. Momentarily activating the + RES switch will recall the previous vehicle speed, after the
cruise control system has been disengaged by pressing the brake pedal, or CANCEL switch. Refer to the vehicle
Owner's Manual for more information.

Cruise Control Disengaged

The engine control module (ECM) disengages the cruise control operation based on the signals from the
following switches:

The Cruise Control System will disengage when the brake pedal is applied. The body control module (BCM)
monitors the BPP sensor via the BPP sensor signal circuit as the voltage signal increases while the pedal is
further applied. The ECM monitors the BPP signal through a discrete input and a serial data message signal
from the BCM indicating the brake status. When either signal indicates the brake pedal is applied, the ECM will
disengage the cruise control system.

The Cruise Control System will also disengage when the cruise control on/off switch is switched OFF, or the
cruise control cancel switch is activated. The body control module (BCM) determines when the cruise control
cancel switch is activated. When the normally open cancel switch is closed, the BCM detects the predetermined
voltage signal on the cruise control function switch circuit. The vehicle speed stored in the memory of the
engine control module will be erased when the cruise control On/Off switch is turned OFF, or the ignition
switch is turned OFF. The BCM sends a serial data message to the ECM in order to disengage the cruise control
system. When the Cruise Control System has been disengaged, the ECM sends a serial message to the
instrument panel cluster (IPC) in order to turn OFF the Cruise Engaged indicator.

Every time the Cruise Control System is disengaged, the ECM will keep track of the reason for system
disengagement. The last 8 disengagement reasons will be recorded within the ECM memory. The scan tool will
display the last 8 Cruise Disengage History parameters, in which one out of approximately 50 possible reasons
will be displayed in each of these 8 parameters. For the disengagement reason to be displayed within the scan
tool parameter the Cruise Control System is active and disengagement is requested.

When engagement of the system is requested but an engagement inhibit is present, the most recent inhibit
reason is recorded in the ECM history. The scan tool will display the most recent inhibit reason, in which one
out of approximately 50 possible reasons will be displayed.

Cruise Control Inhibited

The engine control module (ECM) inhibits the cruise control operation when any of the following conditions
exist:

Cruise Control Inhibit Reasons

This is a general list of inhibit reasons. Not every inhibit reason is applicable to all vehicles. Refer to the scan
tool inhibit reason list for the last 8 reasons that have been recorded during the current ignition cycle.

Scan Tool Name

Description

Long Description

Acceleration Rate too High

High acceleration

The vehicle acceleration rate is too
high.

Acceleration Time

Rate limiting fault

Cruise torque request rate limiting
active too long.

Adaptive Cruise Control
Configuration Incorrect

Adaptive cruise control option
mismatch

The cruise control type (adaptive
cruise or conventional cruise) is
mismatched between the engine
control module (ECM) and the body
control module (BCM).

Antilock Braking System
Active

Antilock Braking System Active

The antilock braking system was
active. Only reported on enhanced
cruise control vehicles.

Automatic Braking Engine
Torque Request Signal
Communication Malfunction

Automatic braking engine torque
request signal communication
malfunction

An engine control module to electronic
brake control module (EBCM) serial
data fault is active or communication
has been lost between the modules.

Automatic Braking Malfunction

Brake system malfunction

The electronic brake control module
has detected a failure that does not
allow automatic braking to be
performed.

Axle Torque Serial
Communication Malfunction

Axle Torque Serial
Communication Malfunction

The adaptive cruise control is being
inhibited by the ECM because a serial
data signal timeout error has occurred
with the hybrid max/min torque
signals.

Battery Voltage Too High

Voltage above high voltage
threshold

The ignition voltage is too high at the
engine control module (typically 18
volts).

Battery Voltage Too Low

Voltage below low voltage
threshold

The ignition voltage is low at the
engine control module (typically 9
volts).

Brake Pedal Applied

Brake pedal apply

The brake pedal was applied.

Scan Tool Name

Description

Long Description

Brake Pedal Not Initialized

Brake before cruise

The brake pedal has not been seen as
applied prior to driver request to
engage cruise with set switch. A brake
pedal apply must be seen before
allowing cruise engagement during
each key cycle. On a vehicle equipped
with a manual transmission, a clutch
pedal apply may satisfy the brake
pedal apply criteria.

Brake Pedal Position
Malfunction

Brake pedal position signal
invalid

A brake pedal apply circuit fault has
been detected.

Brake Pedal Position Signal
Malfunction

DTC P0703 is active or
maximum time elapsed without
receiving a valid Brake Pedal
Position signal.

A serial data fault is active or
communication has been lost with the
module sending the brake pedal apply
state.

Brake Pedal Pressure Detected

Brake pedal driver applied
pressure detected

A brake pedal apply has been detected
based on brake pedal pressure as
measured by the electronic brake
control module.

Brake Pedal Released Position
Not Learned

Brake apply sensor home
position not learned

The brake pedal position sensor
released position is not learned.

Brake System Malfunction

Adaptive cruise control
automatic braking failed

Adaptive cruise control automatic
braking inoperative.

Calculated Torque

Calculated engine torque

The engine torque calculation is
incorrect.

Clutch Pedal Applied

Clutch switch active

The clutch pedal was applied.

Coast Below Minimum Speed

Coast below low speed inhibit

The Set/Coast switch was depressed
and the vehicle slowed below the
minimum cruise control operating
speed.

Coast Mode

Coast disengage

Cruise control is in coast mode with
the Set/Coast switch depressed and is
requesting no throttle.

Control Function Active

DLC override

A scan tool is plugged into the Data
Link Connector (DLC) connector.

Control Module Memory
Malfunction

Memory failure

A control module memory failure has
been detected.

Control Module Processor
Malfunction

Processor integrity fault (random
access memory corruption)

An engine control module software
error has occurred.

Crawl Mode Active

Crawl Mode Active

Crawl mode is active and inhibiting
cruise control.

Cruise Control Cancel Switch
Active

Cancel switch active

The cruise control cancel switch was
depressed.

Scan Tool Name

Description

Long Description

Cruise Control Software
Malfunction

Sequence of completion checks

A cruise control software execution
error has occurred.

Cruise Control Switch Inactive

On/Off switch in Off state

The cruise control On/Off switch is
turned off.

Cruise Control Switch Invalid

Analog cruise switch input out of
range

The cruise control switch voltage
signal is in an invalid range.

Cruise Control Switch Serial
Communication Malfunction

Serial data fault (cruise switch
serial communication fault)

The cruise control switch serial data
fault is active or communication has
been lost with the module sending
cruise control switch states.

Deceleration Rate Too High

High deceleration

The vehicle deceleration rate is too
high.

Diagnostic Trouble Code
(DTC) Set

Malfunction in PCM/ECM (DTC
active)

A DTC is active or in history that
inhibits cruise control operation.

Distance Sensing Cruise
Control Brake Pedal Applied

Distance Sensing Cruise Control
Brake Pedal Applied

Adaptive cruise control is being
inhibited by the ECM because a brake
pedal apply has occurred.

Distance Sensing Cruise
Control Cancel Switch Active

Distance Sensing Cruise Control
Cancel Switch Active

Adaptive cruise control is being
inhibited by the ECM because the
driver applied the cancel switch.

Distance Sensing Cruise
Control Data

Serial data fault for adaptive
cruise control throttle control
and brake control signals sent by
the distance sensing cruise
control module

A distance sensing cruise control
module serial data fault is active or
communication has been lost between
the distance sensing cruise control
module and the engine control module.

Distance Sensing Cruise
Control Inhibit

Distance sensing cruise control
inhibited

The distance sensing cruise control
system is inhibited.

Distance Sensing Cruise
Control Invalid Engage

Distance Sensing Cruise Control
Invalid Engage

Adaptive cruise control is being
inhibited by the ECM because an
invalid sequence of cruise control
applies, brake pedal applies, or an
invalid speed range has been detected.

Distance Sensing Cruise
Control Off

Distance Sensing Cruise Control
Off

Adaptive cruise control is being
inhibited by the ECM because the
driver has turned off the cruise on/off
switch.

Distance Sensing Cruise
Control Reduced Engine Power

Distance Sensing Cruise Control
Reduced Engine Power

Adaptive cruise control is being
inhibited by the ECM due to a fault
resulting in "Reduced Engine Power".

Driven Wheel Speed Higher
Than Non Driven Wheel Speed

Driven wheel speed greater
(wheel slip detection)

The driven wheel speed is greater than
the non driven wheel speed (slip
detection).

Engine Control Module

PCM/ECM inhibit (RAM
corruption)

Engine control module internal
communication error.

Scan Tool Name

Description

Long Description

Engine Control Module (ECM)
Reset

ECM running reset

An engine control module running
reset has occurred.

Engine Overspeed Protection
Active

Injectors disabled (engine
overspeed fuel cut-off active)

Engine RPM limiter active with fuel
cut off active.

Engine Overtemperature
Protection Active

Engine metal overtemp active

The engine is over temperature. The
engine is overheated.

Engine Run Time

Engine run time not elapsed

The engine has not been running long
enough, typically five seconds.

Engine Speed

Engine speed too low or too high

The engine RPM is too low (near stall)
or too high (near engine RPM fuel
shutoff).

Excessive Accelerator Position
Override

Pedal greater than cruise
(override)

The driver has overridden cruise
control set speed with accelerator
pedal for greater than an allowable
time.

1st Gear

First Gear

Transmission is engaged in 1st gear.

Gear Change without Applied
Clutch Pedal

Manual transmission out of gear
with no clutch pedal apply

Manual transmission shifted to Neutral
without clutch pedal being applied.

Hill Descent Control Active

Hill Descent Control System
Active

The hill descent control system has
gone active.

Hill Descent Control Serial
Communication Malfunction

Hill Descent Control Serial
Communication Malfunction

An electronic brake control module
serial data fault is active or
communication has been lost between
the EBCM and ECM.

Hybrid/EV System

Hybrid Cruise Disengage

Cruise control is inhibited on hybrid
applications when "Regen on Demand"
is requested by the driver via the tap-
up/tap-down paddles.

Illegal Mode

Illegal cruise mode

The cruise control mode is incorrect
based on switch states.

Lane Center Control Serial
Data Error

Lane Center Control Serial
Communication Malfunction

Adaptive cruise control is being
inhibited by the ECM because a serial
data error has been detected on a
vehicle with Lane Center Control.

Non Driven Wheel Speed
Higher Than Drive Wheel
Speed

Non-driven wheel speed greater

The non driven wheel speed is greater
than the driven wheel speed.

None

None

This disengagement reason may be
displayed after a dead battery repair or
module replacement.

Park Brake Applied

Park brake switch signal active

The parking brake is applied.

Power Take-Off Active

Power Take Off active

The Power Take Off (PTO) system is
active.

Rear Axle in Low Range

Rear axle in low

The rear axle is in low range.

Scan Tool Name

Description

Long Description

Set/Coast and

Resume/Accelerate Switches

Active Simultaneously

SET and RESUME switches
simultaneously active

The Set/Coast and Resume/Accelerate
switches were pressed simultaneously.

Set/Coast Switch Active With
Vehicle Speed Higher Than Set
Point

Over schedule tap-down

The Set/Coast switch is selected,
vehicle speed is above set speed and
does not decrease. May be due to
traveling down hill.

Speed Limiting/Warning

System On

Speed limiter/warning On/Off
switch turned on

Driver has turned on the Speed
Limiter/Warning on/off switch. Cruise
is disabled/inhibited and cruise on/off
switch will be set to Off.

Throttle Actuator Control
System

Electronic throttle control
prevents cruise operation

The electronic throttle control system
has detected a failure in the throttle
control hardware.

Traction Control Active

Traction control active

The traction control system was active.

Traction Control System
Malfunction

Traction Control System
Malfunction

A fault is present in the traction control
system.

Traction Control System Off

Traction Control System Off

The traction control system has been
turned off by the driver.

Transfer Case in 4WD Low
Range

Transfer case in 4WD Low

The transfer case is in low range.

Transmission Gear Ratio
Malfunction

Transmission gear fault

A transmission DTC is active or in
history, that inhibits cruise control
operation.

Transmission Not in Forward
Gear

Transmission in neutral, reverse
or park

The transmission gear selector is not in
a forward gear.

Vehicle Overspeed Protection
Active

MPH limited fuel (vehicle
overspeed fuel cut-off active)

The vehicle overspeed protection is
active with fuel cut off active.

Vehicle Speed Higher Than Set
Point

Over schedule

Vehicle speed has exceeded driver
selected set speed by more than an
allowable amount. This may occur
while driving down a significant grade
or driver overriding cruise while
performing a passing maneuver.

Vehicle Speed Lower Than Set
Point

Under schedule

The vehicle speed is below cruise
control set speed by more than an
allowable amount.

Vehicle Speed Too High

Vehicle speed exceeds high
speed threshold

Vehicle speed has exceeded maximum
cruise operating speed.

Vehicle Speed Too Low

Vehicle speed drops below low
speed threshold

Vehicle speed dropped below the
cruise control minimum operating
speed. May be due to hilly terrain and
low vehicle speed. Manual
transmission gear selection and engine

Scan Tool Name

Description

Long Description

torque may contribute to this
disengagement reason.

Vehicle Stability System Active

Vehicle stability control active

The vehicle stability control system
was active.

Vehicle Stability System
Malfunction

Vehicle Stability System
Malfunction

A fault has been detected in the vehicle
stability control system.

Vehicle Stability System Off

Vehicle Stability System Off

The vehicle stability control system
has been turned off by the driver.

Article GUID: A00884711

ACCESSORIES & EQUIPMENT

Data Communications - Description and Operation - Volt

DESCRIPTION AND OPERATION

BODY CONTROL SYSTEM DESCRIPTION AND OPERATION

The body control system consists of the body control module (BCM), communications, and various input and
outputs. Some inputs, outputs and messages require other modules to interact with the BCM. The BCM also has
discrete input and output terminals to control the vehicle's body functions. The BCM is wired to the high speed
GMLAN serial data bus, low speed GMLAN serial data bus and Multiple LIN buses and acts as a gateway
between them.

Power Mode Master

This vehicle body control module (BCM) functions as the power mode master (PMM). The ignition switch is a
low current switch with multiple discrete ignition switch signals to the PMM for determining the power mode
that will be sent over the serial data circuits to the other modules that need this information; the PMM will
activate relays and other direct outputs of the PMM as needed. Refer to
Power Mode Description and
Operation
for a complete description of power mode functions.

Gateway

The body control module (BCM) in this vehicle functions as a gateway or translator. The purpose of the
gateway is to translate serial data messages between the GMLAN high speed bus and the GMLAN low speed
bus for communication between the various modules. The gateway will interact with each network according to
that network's transmission protocol.

All communication between the BCM and a scan tool is on the high speed GMLAN serial data circuits. A lost
communication DTC typically is set in modules other than the module with a communication failure.

Body Control

The various body control module (BCM) input and output circuits are illustrated in the corresponding functional
areas on the BCM electrical schematics. Refer to the
Body Control System Schematics for more detailed
information.

DATA LINK COMMUNICATIONS DESCRIPTION AND OPERATION

NOTE: This is an overview of different serial data buses used by GM control modules
to communicate with each others. Use schematics to find out which serial data
buses are configured for a specific vehicle.

Circuit Description

There are many components in a vehicle that rely on information from other sources, transmit information to
other sources, or both. Serial data communication networks provide a reliable, cost effective, way for various
components of the vehicle to "talk" to one another and share information.

GM uses a number of different communication buses to insure the timely and efficient exchange of information
between control modules. When compared to each other, some of these buses are different in nature as far as
speed, signal characteristics, and behavior. An example of this is the High Speed GMLAN and Low Speed
GMLAN buses.

On the other hand, when other buses are compared to each other they have similar characteristics and simply
operate in parallel. In this case they are used to group together components which have high interaction.
Examples are the High Speed GMLAN, Powertrain Expansion, and Chassis Expansion buses. This allows them
to communicate with each other on a bus with reduced message congestion insuring faster and the more timely
exchange of information than if all vehicle control modules were on a single bus.

The majority of information that exists within a given network generally stays local; however some information
will have to be shared on other networks. Control modules designated as Gateway's perform the function of
transferring information between the various buses. A Gateway module is connected to at least 2 buses and will
interact with each network according to its message strategy and transmission models.

GMLAN provides the capability for a receiving control module to monitor message transmissions from other
control modules in order to determine if messages of interest are not being received. The primary purpose is to
allow reasonable default values to be substituted for the information no longer being received. Additionally, a
control module may set a Diagnostic Trouble Code to indicate that the control module it is expecting
information from is no longer communicating.

High Speed GMLAN Circuit Description

A High Speed GMLAN Bus is used where data needs to be exchanged at a high enough rate to minimize the
delay between the occurrence of a change in sensor value and the reception of this information by a control
device using the information to adjust vehicle system performance.

The High Speed GMLAN serial data network consists of two twisted wires. One signal circuit is identified as
GMLAN-High and the other signal circuit is identified as GMLAN-Low. At each end of the data bus there is a
120 Q termination resistor between the GMLAN-High and GMLAN-Low circuits.

Data symbols (1's and 0's) are transmitted sequentially at a rate of 500 Kbit/s. The data to be transmitted over
the bus is represented by the voltage difference between the GMLAN-High signal voltage and the GMLAN-
Low signal voltage.

When the two wire bus is at rest the GMLAN-High and GMLAN-Low signal circuits are not being driven and
this represents a logic "1". In this state both signal circuits are at the same voltage of 2.5 V. The differential
voltage is approximately 0 V.

When a logic "0" is to be transmitted, the GMLAN-High signal circuit is driven higher to about 3.5 V and the
GMLAN-Low circuit is driven lower to about 1.5 V. The differential voltage becomes approximately 2.0 (+/-
0.5) V.

Chassis High Speed GMLAN Circuit Description

The GMLAN Chassis Expansion Bus is basically a copy of the High Speed GMLAN Bus except that its use is
reserved for chassis components. This implementation splits message congestion between two parallel buses
helping to insure timely message transmission and reception. Sometimes communication is required between
the Chassis Expansion Bus and the primary High Speed GMLAN Bus. This is accomplished by using the K17
Electronic Brake Control Module (EBCM) as the Gateway module. Since the High Speed GMLAN Chassis
Expansion Bus and primary High Speed GMLAN Bus operate in the same manner, the diagnostics for each are
similar.

Powertrain High Speed GMLAN Circuit Description

The GMLAN Powertrain Expansion Bus is basically a copy of the High Speed GMLAN Bus except that its use
is reserved for Hybrid powertrain components or Diesel powertrain components in some cases. The bus is
optional based upon feature content. Sometimes communication is required between the Powertrain Expansion
Bus and the primary High Speed GMLAN Bus. This is accomplished by using the K20 Engine Control Module
(ECM) as the Gateway module. Since the High Speed GMLAN Powertrain Expansion Bus and the primary
High Speed GMLAN Bus operate in the same manner, the diagnostics for each are similar.

All diagnostic information is available only through the primary high speed GMLAN bus.

High Voltage Energy Management High Speed GMLAN Circuit Description

The GMLAN High Voltage Energy Management Bus is basically a copy of the High Speed GMLAN Bus
except that its use is reserved for Hybrid charging components of an electric vehicle. Sometimes
communication is required between the Low Speed GMLAN Bus and the High Voltage Energy Management
Bus. This is accomplished by using the K114B Hybrid Powertrain Control Module 2 as the Gateway module.
Since the High Speed GMLAN High Voltage Energy Management Bus and primary High Speed GMLAN Bus
operate in the same manner, the diagnostics for each are similar.

All diagnostic information is available only through the primary high speed GMLAN bus.

Object High Speed GMLAN Circuit Description

The GMLAN Object Bus is basically a copy of the High Speed GMLAN Bus except that its use is reserved for
the enhanced safety system. This implementation is used to isolate the heavy communication among the
enhanced safety system devices from the other vehicle buses, reducing congestion. The K124 Active Safety
Control Module is connected to the Object Bus as well as the Primary High Speed GMLAN Bus, the Chassis
Expansion Bus, and the Low Speed GMLAN Bus. The K124 Active Safety Control Module acts as a Gateway
module for all required communication between the Object Bus devices and devices on these other vehicle
buses. The GMLAN Object Bus operates in the same manner as the Chassis Expansion and Primary High Speed
buses and so the diagnostics are similar. The Object Bus is physically partitioned into a Front Object Bus and a
Rear Object Bus with each partition having its own communication enable circuit to activate the partition, but
functional operation of both is identical. The Front Object Bus standard devices are the K124 Active Safety
Control Module, the K109 Frontview Camera Module, and the B233B Radar Sensor Module - Long Range. The
Front Object Bus optional devices are the B233LF Radar Sensor Module - Short Range Left Front and the
B233RF Radar Sensor Module - Short Range Right Front. The Rear Object Bus is optional and when present
will have the K124 Active Safety Control Module and B233R Radar Sensor Module - Short Range Rear on the
bus, and optionally the Radar Sensor Module - Short Range Right Rear. All Object Bus components are
powered by the K124 Active Safety Control Module via the communication enable circuits, except the K109
Frontview Camera Module which is powered directly by battery.

Media Oriented Systems Transport (MOST) Circuit Description

The MOST Infotainment network is a dedicated high speed multimedia streaming data bus independent from
GMLAN. The MOST bus will be configured in a physical hardwired loop with each device within the bus sends
and receives data on an assigned MOST addresses in a set order. Each device on the MOST bus will be required
to have twisted pair copper wires (2 transmit TX, 2 receive RX, and 1 electronic control line which is a 12 V
wakeup signal line). The A11 Radio is the MOST Master and will monitor the bus for vehicle configuration,
Infotainment data messages and errors on the bus. The MOST initialization consists of a short 100 ms low
voltage pulse on the electronic control line (or MOST control line) connected to all devices contained on the
MOST ring. When the MOST devices receive this wakeup message, they will respond with a generic device
response. Once these initial responses on the MOST bus are reported successfully without error to the A11
Radio, the next responses will report the MOST device addresses, their functionality requirements and
capabilities within. The A11 Radio will learn this information and also record the address node sequence on the
MOST bus at this point. This node address list will now be stored within the A11 Radio as the MOST bus
configuration (called "Last Working MOST ID of Node 1 - 9" on scan tool data display).

When MOST receive, transmit, or control line faults are detected, transmit/receive messages will not be
received as expected from the wakeup request. The A11 Radio and the K74 Human Machine Interface Control
Module will then perform diagnostics to isolate these MOST faults. If the MOST control line is shorted low to 0
V for excess amount of time, the A11 Radio will set a U2098 DTC and K74 Human Machine Interface Control
Module will set a U0029 02 DTC. At this point the MOST bus will be unable to communicate until the shorted
MOST control line is repaired.

Once the shorted MOST control line diagnostics pass, the A11 Radio will attempt to resend the initial short
pulse attempts up to 3 times on the MOST control line. If the expected responses are not received, the A11
Radio continues into a failure mode setting a U0028 DTC and will continue on to send 300 ms long pulses
while DTC U0028 is current, which will enable the furthest upstream transmitting device to become the
surrogate MOST Master in this MOST fault/diagnostic mode. When the A11 Radio receives this new MOST
Master identity, the surrogate MOST master device can be identified based on scan tool data parameter
"Surrogate MOST Master Node Upstream Position". The scan tool and schematics will be used to determine the
MOST bus configuration and direction by utilizing the "Last Working MOST ID of Node 1 - 9" parameters
from the A11 Radio data display. When a fault is present, it will indicate the newly enabled "Surrogate MOST
Master Node Upstream Position" to the A11 Radio. This will assist in determining the location of the MOST
device/bus/control fault. The MOST device and circuits upstream from the surrogate MOST master device,
transmit, receive, or control lines will be the suspect areas for diagnostics at this point. These faults can be
associated with any of the MOST transmit, receive, or control line twisted copper wires or possibly an internal
device fault.

DTC U0028 will take approximately 10 s for diagnostics to set in the A11 Radio with an active fault condition.
With the latest software, the A11 Radio will report the Surrogate MOST Master Node Upstream Position value
when DTC U0028 is stored in history. When there is no MOST bus fault, this value is None. The U0028 DTC
state and the Number of MOST Communication Breaks parameter must be used with the Surrogate MOST
Master Node Upstream Position parameter for a successful diagnosis. This is used to help capture surrogate
information on intermittent fault conditions. The Number of MOST Communication Breaks counter will
increment each time the MOST bus state transitions from Normal Operation (Lock status) to Off State (Unlock
status) and will accumulate from 0-65535. After the Number of MOST Communication Breaks counter
increments 10 times, DTC U0028 will be set. It is important to clear DTC U0028 and reset the Surrogate MOST
Master Node Upstream Position value to None after a successful repair. The Surrogate MOST Master Node
Upstream Position value can be reset to None by disconnecting the A11 Radio power, disconnecting battery
cables, or 50 ignition power down cycles. This will also reset the Number of MOST Communication Breaks
counter to 0.

The K74 Human Machine Interface Control Module will set a U0029 00 DTC when it diagnoses a MOST bus
not communicating properly after one attempt. When the DTC U0029 00 is set by the K74 Human Machine
Interface Control Module without the corresponding DTC U0028 from the A11 Radio, it will be an indication
of an intermittent wiring/device condition. The A11 Radio may also set a U0029 7F DTC if there is an
intermittent wiring/device condition.

Low Speed GMLAN Circuit Description

Low Speed GMLAN Bus is used in applications where a high data rate is not required which allows for the use
of less complex components. It is typically used for operator controlled functions where the response time
requirements are slower than those required for dynamic vehicle control.

The Low Speed GMLAN Serial Data Network consists of a single wire, ground referenced bus with high side
voltage drive. During on road vehicle operation data symbols (1's and 0's) are transmitted sequentially at the
normal rate of 33.3 Kbit/s. For component programming only, a special high speed data mode of 83.3 Kbit/s
may be used.

Unlike the high speed dual wire networks, the single wire low speed network does not use terminating resistors
at either end of the network.

The data symbols to be transmitted over the bus are represented by different voltage signals on the bus. When
the Low Speed GMLAN Bus is at rest and is not being driven, there is a low signal voltage of approximately
0.2 V. This represents a logic "1". When a logic "0" is to be transmitted, the signal voltage is driven higher to
around 4.0 V or higher.

Local Interconnect Network (LIN) Circuit Description

The Local Interconnect Network (LIN) Bus consists of a single wire with a transmission rate of 10.417 Kbit/s.
This bus is used to exchange information between a master control module and other smart devices which
provide supporting functionality. This type of configuration does not require the capacity or speed of either a
High Speed GMLAN Bus or Low Speed GMLAN Bus and is thus relatively simpler.

The data symbols (1's and 0's) to be transmitted are represented by different voltage levels on the
communication bus. When the LIN Bus is at rest and is not being driven, the signal is in a high voltage state of
approximately Vbatt. This represents a logic "1". When a logic "0" is to be transmitted, the signal voltage is
driven low to about ground (0.0 V).

Communication Enable Circuit Description

Control modules on GMLAN high speed type networks enable or disable communication based on the voltage
level of this circuit. When the circuit voltage is high (around 12 V), communications are enabled. When the
circuit is low, communications are disabled.

Data Link Connector (DLC)

The data link connector (DLC) is a standardized 16-cavity connector. Connector design and location is dictated
by an industry wide standard, and is required to provide the following:

Serial Data Reference

The scan tool communicates over the various buses on the vehicle. When a scan tool is installed on a vehicle,
the scan tool will try to communicate with every control module that could be optioned into the vehicle. If an
option is not installed on the vehicle, the scan tool will display No Comm (or Not Connected) for that optional
control module. In order to avert misdiagnoses of No Communication with a specific control module, refer to
Data Link References for a list of control modules and the buses they communicate with. Use schematics and
specific vehicle build RPO codes to determine optional control modules.

Article GUID: A00884674

ACCESSORIES & EQUIPMENT

Data Communications - Diagnostic Information and Procedures - Volt

DIAGNOSTIC INFORMATION AND PROCEDURES

CONTROL MODULE U CODE LIST

This list includes all Data Communications related U-code DTCs in alphanumeric order with descriptors for all
devices. Not all DTCs listed will be applicable to all vehicles.

For symptom byte information, refer to Symptom Byte List .

DTC

DTC Descriptor

U0001

High Speed CAN Bus Malfunction

U0002

High Speed CAN Bus

U0009

High Speed CAN Bus [-] Shorted to Bus [+]

U0020

Low Speed CAN Bus

U0028

MOST Bus

U0029

MOST Bus Performance

U0073

Control Module Communication Bus A Off

Control Module Communication High Speed CAN Bus Off

U0074

Control Module Communication Bus B Off

Control Module Communication Powertrain Expansion CAN Bus Off

U0075

Control Module Communication Object Detection CAN Bus Off

U0076

Control Module Communication Powertrain Sensor CAN Bus Off

U0077

Control Module Communication Chassis Expansion CAN Bus Off

U0078

Control Module Communication Low Speed CAN Bus Off

U007A

Control Module Communication High Voltage Energy Management CAN Bus Off

U007B

Control Module Communication High Speed Extension CAN Bus Off

U007C

Control Module Communication High Speed Extension CAN Bus 2 Off

U007D

Control Module Communication Low Speed Extension CAN Bus Off

U007E

Control Module Communication FlexRay 1A Bus Off

U007F

Control Module Communication FlexRay 1B Bus Off

U0100

Lost Communication With Engine Control Module

U0101

Lost Communication With Transmission Control Module

U0102

Lost Communication with Transfer Case Control Module

U0103

Lost Communication with Shift Lever Module

U0104

Lost Communication With Cruise Control Module

U0105

Lost Communication with Fuel Injector Control Module

U0106

Lost Communication with Glow Plug Control Module

U0109

Lost Communication with Fuel Pump Control Module (2013 and prior)

Lost Communication with Chassis Control Module (2014 and beyond)

DTC

DTC Descriptor

U010C

Lost Communication with Turbocharger Boost Control Module

U010E

Lost Communication with Reductant Sensor Module

U010F

Lost Communication with Air Conditioning Control Module

U0111

Lost Communication with Battery Energy Control Module

U0112

Lost Communication with Battery Energy Control Module

U0114

Lost Communication with Four Wheel Drive Clutch Control Module

U0115

Lost Communication with Engine Control Module B

U0117

Lost Communication With Power Take-Off Control Module

U0121

Lost Communication With Electronic Brake Control Module

U0122

Lost Communication With Vehicle Stability Control Module

U0123

Lost Communication with Yaw Rate Sensor Module

U0125

Lost Communication With Multi-Axis Acceleration Sensor Module

U0126

Lost Communication With Steering Wheel Angle Sensor Module

U0128

Lost Communication With Park Brake Control Module

U0129

Lost Communication with Brake System Control Module

U012A

Lost Communication With Chassis Control Module

U0130

Lost Communication With Power Steering Control Module

U0131

Lost Communication With Power Steering Control Module

U0132

Lost Communication With Suspension Control Module

U0133

Lost Communication With Air Suspension Control Module

U0134

Lost Communication with Power Steering Control Module - Rear

U0136

Lost Communication With Differential Control Module - Rear

U0137

Lost Communication with Trailer Brake Control Module

U0139

Lost Communication With Suspension Control Module 2

U0140

Lost Communication With Body Control Module

U0146

Lost Communication with Serial Data Gateway Module

U0151

Lost Communication With Inflatable Restraint Sensing and Diagnostic Module

U0154

Lost Communication with Passenger Presence Module

U0155

Lost Communication With Instrument Cluster

U0158

Lost Communication With Head-Up Display

U0159

Lost Communication With Parking Assist Control Module

U0160

Lost Communication With Chime Alarm Control Module

U0164

Lost Communication with HVAC Control Module

U0166

Lost Communication with Auxiliary Heater Control Module

U0167

Lost Communication with Immobilizer Control Module

U0168

Lost Communication With Keyless Entry Control Module

U016B

Lost Communication with Electric A/C Compressor Control Module

U0170

Lost Communication with Passenger Presence Detection Sensor Module

U017E

Lost Communication with Seat Belt Retractor Motor Module

U0181

Lost Communication with Automatic Headlamp Leveling Control Module

U0182

Lost Communication With Lighting Control Module - Front

DTC

DTC Descriptor

U0184

Lost Communication With Radio

U0186

Lost Communication With Speaker Amplifier Module

U0196

Lost Communication With Rear Audio Control Module

U0191

Lost Communication With Television

U0193

Lost Communication With Digital Radio Receiver Control Module

U0197

Lost Communication With Telephone Control Module

U0198

Lost Communication with Telematics Communication Interface Control Module

U019E

Lost Communication With Transmission Range Control Module

U01A0

Lost Communication with Hybrid/EV Battery Interface Control Module 1

U01A1

Lost Communication with Hybrid/EV Battery Interface Control Module 2

U01A2

Lost Communication with Hybrid/EV Battery Interface Control Module 3

U01A3

Lost Communication with Hybrid/EV Battery Interface Control Module 4

U01A4

Lost Communication with Hybrid/EV Battery Interface Control Module 5

U01A5

Lost Communication with Hybrid/EV Battery Interface Control Module 6

U01A6

Lost Communication with Hybrid/EV Battery Interface Control Module 7

U01A7

Lost Communication with Hybrid/EV Battery Interface Control Module 8

U01B0

Lost Communication with Battery Monitor Module

U01B4

Lost Communication with Brake System Control Module 2

U0201

Lost Communication with Passenger Door Switch Panel Control Module

U0203

Lost Communication With Left Rear Door Switch Panel Control Module

U0204

Lost Communication With Right Rear Door Switch Panel Control Module

U0207

Lost Communication With Moveable Roof Control Module

U0208

Lost Communication with Seat Memory Control Module

U0209

Lost Communication With Front Seat Heating Control Module

U0210

Lost Communication With Rear Seat Heating Control Module

U0230

Lost Communication With Liftgate Control Module

U0231

Lost Communication with Rain Sensor Module

U0232

Lost Communication with Side Object Detection Control Module - Left

U0233

Lost Communication with Side Object Detection Control Module - Right

U0236

Lost Communication With Steering Column Lock Module

U0237

Lost Communication With Multimedia Player Interface Module

U023A

Lost Communication With Vehicle Direction Camera Control Module (without
UGN)

Lost Communication With Active Safety Control Module 1 (with UGN)

U023B

Lost Communication with Active Safety Control Module 2

U023C

Lost Communication with Night Vision Camera Control Module

U0241

Lost Communication With Left Headlamp High Beam Control Module

U0242

Lost Communication With Right Headlamp High Beam Control Module

U0248

Lost Communication with Remote Accessory Module

U0249

Lost Communication with Rear Seat Entertainment Control Module

U0250

Lost Communication with Impact Classification System Module

DTC

DTC Descriptor

U0252

Lost Communication With Trailer Interface Control Module

U0253

Lost Communication with Accessory Protocol Interface Module

U0254

Lost Communication With Remote Start Module

U0255

Lost Communication With Info Display Module

U0256

Lost Communication With Infotainment Faceplate Control Module

U0257

Lost Communication With Info Display Module/Infotainment Faceplate Control
Module

U0259

Lost Communication with Special Purpose Vehicle Control Module

U025B

Lost Communication with Special Purpose Vehicle Control Module "C"

U025C

Lost Communication with Special Purpose Vehicle Control Module "D"

U0264

Lost Communication With Camera Module - Rear

U0265

Lost Communication with Left Front Short Range Radar Sensor Module

U0266

Lost Communication with Night Vision Camera

U0268

Lost Communication with Right Front Short Range Radar Sensor Module

U0269

Lost Communication with Front Long Range Object Sensor

U026A

Lost Communication with Frontview Camera Module

U026B

Lost Communication with Rear Short Range Object Sensor

Lost Communication with Left Rear Short Range Radar Sensor Module

U026C

Lost Communication with Right Rear Short Range Radar Sensor Module

U026D

Lost Communication with Rear Middle Short Range Radar Sensor Module

U0284

Lost Communication with Active Grille Air Shutter 1 Motor Module

U0285

Lost Communication with Active Grille Air Shutter 2 Motor Module

U0293

Lost Communication with Hybrid/EV Powertrain Control Module

U0298

Lost Communication with DC/DC Converter Control Module

U029D

Lost Communication with NOx Sensor 1 Module

U029E

Lost Communication with NOx Sensor 2 Module

U02A3

Lost Communication With Particulate Matter Sensor Module

U0301

Software Incompatibility with Engine Control Module

U0302

Software Incompatibility with Transmission Control Module

U0305

Software Incompatibility With Cruise Control Module

U0315

Software Incompatibility with Electronic Brake Control Module

U031C

Software Incompatibility With Brake System Control Module 2

U0401

Invalid Data Received From Engine Control Module

U0402

Invalid Data Received From Transmission Control Module

U0403

Invalid Data Received From Transfer Case Control Module

U0405

Invalid Data Received From Cruise Control Module

U0414

Invalid Data Received From Four Wheel Drive Clutch Control Module

U0415

Invalid Data Received From Electronic Brake Control Module

U0416

Invalid Data Received From Vehicle Dynamics Control Module

U0417

Invalid Data Received From Park Brake Control Module

U0418

Invalid Data Received From Brake System Control Module

DTC

DTC Descriptor

U0420

Invalid Data Received From Power Steering Control Module

U0421

Invalid Data Received From Suspension Control Module

U0422

Invalid Data Received From Body Control Module

U0423

Invalid Data Received From Instrument Cluster

U0424

Invalid Data Received From HVAC Control Module

U0428

Invalid Data Received From Steering Wheel Angle Sensor Module

U042B

Invalid Data Received From Chassis Control Module

U0431

Invalid Data Received From Body Control Module "A"

U0432

Invalid Data Received From Multi-axis Acceleration Sensor Module

U0437

Invalid Data Received From Differential Control Module - Rear

U0438

Invalid Data Received From Trailer Brake Control Module

U0447

Invalid Data Received from Central Gateway Module

U0452

Invalid Data Received From Inflatable Restraint Sensing and Diagnostic Module

U045A

Invalid Data Received From Parking Assist Control Module "A"

U0465

Invalid Data Received From Power Take-Off Control Module

U0499

Invalid Data Received From Telematics Communication Interface Control Module

U0513

Invalid Data Received From Yaw Rate Sensor Module

U053B

Invalid Data Received From Active Safety Control Module 1

U053C

Invalid Data Received From Active Safety Control Module 2

U056B

Invalid Data Received From Frontview Camera Module

U0594

Invalid Data Received From Hybrid/EV Powertrain Control Module

U063E

Lost Communication with Exhaust Heat Exchanger Exhaust Bypass Valve

U0656

Lost Communication with Turbocharger Boost Control Position Sensor

U0657

Lost Communication with Turbocharger/Supercharger Bypass Valve "A" Position
Sensor

U1032

Lost Communication with Vehicle Dynamic Sensor 1

U1033

Lost Communication with Vehicle Dynamic Sensor 2

U1067

Lost Communication with Digital Map Control Module

U1069

Lost Communication with Driver Monitoring System Control Module

U106A

Lost Communication with Multifunction Energy Storage Capacitor Control
Module

U106B

Lost Communication with Multifunction Battery Isolator Control Module

U1112

Lost Communication with Left Headlamp Leveling Device

U1113

Lost Communication with Right Headlamp Leveling Device

U1114

Lost Communication with Left Headlamp Vertical Motor

U1115

Lost Communication with Right Headlamp Vertical Motor

U1343

Chassis Control Module LIN Bus 1

U1345

Engine Control Module LIN Bus 1

U1347

Engine Control Module LIN Bus 3

U1359

Lost Communication with Transmission Range Indicator

U135A

Lost Communication with Shift to Park Range Actuator

DTC

DTC Descriptor

U135B

Lost Communication with Sunload Sensor

U135C

Lost Communication with Start-Stop Capacitor Control Module

U135D

Lost Communication with Transmission Control Module on Chassis Control

Module LIN Bus 2

U135E

Lost Communication with Transmission Control Module on Engine Control
Module LIN Bus 1

U1501

LIN Bus

U1502

LIN Bus

U1505

LIN Bus

U1509

LIN Bus

A26 HVAC Controls / P17 Info Display Module Lost Communication with K33
HVAC Control Module on LIN Bus

U150E

LIN Bus

A22 Radio Controls / P17 Info Display Module Lost Communication with A11
Radio on LIN Bus

U150F

LIN Bus

A22 Radio Controls / P17 Info Display Module Lost Communication with K74
Human Machine Interface Control Module on LIN Bus

K161 Vehicle Performance Data Recorder Lost Communication with K74 Human
Machine Interface Control Module on LIN Bus

U1510

A11 Radio Lost Communication with A20 Radio/HVAC Control / P17 Info
Display Module on LIN Bus

K9 Body Control Module Lost Communication with B67 Ultrasonic Intrusion
Sensor / B165 Content Theft Deterrent Sensor Module on LIN Bus

K20 Engine Control Module Lost Communication with M96 Active Grille Air
Shutter Actuator / M60A Active Grille Air Shutter 1 Motor Module on LIN Bus

K33 HVAC Control Module Lost Communication with A26 HVAC Controls / A20
Radio/HVAC Controls / P17 Info Display Module on LIN Bus

K33 HVAC Control Module Lost Communication with A34 HVAC Controls -
Auxiliary on LIN Bus

K39 Liftgate Control Module Lost Communication with K171 Hands-Free Liftgate
Sensor Control Module / S45A Liftgate Control Switch - Exterior on LIN Bus

P16 Instrument Cluster Lost Communication with S70D Steering Wheel Controls
Switch - Right Upper / S70R Steering Wheel Controls Switch - Right on LIN Bus

U1511

K20 Engine Control Module Lost Communication with M60B Active Grille Air
Shutter 2 Motor Module on LIN Bus

K26 Headlamp Control Module / K28 Headlamp Leveling Control Module Lost
Communication with E13L Headlamp - Left on LIN Bus

K40 Seat Memory Control Module Lost Communication with K99 Steering
Column Position Control Module on LIN Bus

K183 UHF Short Range Low Energy Remote Control Access Transceiver Lost
Communication with B342A UHF Low Energy Remote Control Access Sensor
Transceiver 1 on LIN Bus

DTC

DTC Descriptor

U1512

K26 Headlamp Control Module / K28 Headlamp Leveling Control Module Lost
Communication with E13R Headlamp - Right on LIN Bus

K124B Active Safety Control Module 2 Lost Communication with K187 Steering
Column Friction Control Module on LIN Bus

K183 UHF Short Range Low Energy Remote Control Access Transceiver Lost
Communication with B342B UHF Low Energy Remote Control Access Sensor
Transceiver 2 on LIN Bus

U1513

K26 Headlamp Control Module / K28 Headlamp Leveling Control Module Lost
Communication with E13L Headlamp - Left on LIN Bus

K183 UHF Short Range Low Energy Remote Control Access Transceiver Lost
Communication with B342C UHF Low Energy Remote Control Access Sensor
Transceiver 3 on LIN Bus

U1514

K26 Headlamp Control Module / K28 Headlamp Leveling Control Module Lost
Communication with E13R Headlamp - Right on LIN Bus

K33 HVAC Control Module Lost Communication with A34 HVAC Controls -
Auxiliary on LIN Bus

K183 UHF Short Range Low Energy Remote Control Access Transceiver Lost
Communication with B342D UHF Low Energy Remote Control Access Sensor
Transceiver 4 on LIN Bus

U1515

K9 Body Control Module Lost Communication with M75 Windshield Wiper
Motor / M75L Windshield Wiper Motor Module - Left on LIN Bus

K183 UHF Short Range Low Energy Remote Control Access Transceiver Lost
Communication with B342E UHF Low Energy Remote Control Access Sensor
Transceiver 5 on LIN Bus

U1516

K9 Body Control Module Lost Communication with B110 Battery Sensor Module
on LIN Bus

U1517

K9 Body Control Module Lost Communication with K62 Sunroof Sunshade Motor
Module on LIN Bus

U1518

P16 Instrument Cluster Lost Communication with K78 Head-Up Display Module /
P29 Head-Up Display on LIN Bus

U1519

K40 Seat Memory Control Module Lost Communication with S52 Outside
Rearview Mirror Switch on LIN Bus

K40 Seat Memory Control Module Lost Communication with K96 Mirror Control
Module / K96D Mirror Control Module - Driver / K96L Mirror Control Module -
Left on LIN Bus

U151A

K9 Body Control Module Lost Communication with B117 Rain Sensor / B177
Rain/Ambient Light Sensor Module / B200 Rain Sensor Module on LIN Bus

U151B

K9 Body Control Module Lost Communication with K61 Sunroof Control Module
on LIN Bus

K40 Seat Memory Control Module Lost Communication with S79P Window
Switch - Passenger on LIN Bus

U151C

K33 HVAC Control Module Lost Communication with A34 HVAC Controls -
Auxiliary / K33A HVAC Control Module - Auxiliary on LIN Bus

DTC

DTC Descriptor

U151F

A11 Radio Lost Communication with A20 Radio/HVAC Controls / A22 Radio
Controls / P17 Info Display Module on LIN Bus

U1520

K9 Body Control Module Lost Communication with P4 Security Siren / P25 Power
Sounder Content Theft Deterrent Alarm Module on LIN Bus

K33 HVAC Control Module Lost Communication with M6CR Air Temperature
Door Actuator - Center Console Right Auxiliary on LIN Bus

K40D Seat Memory Control Module - Driver Lost Communication with K134D
Seat Bolster Memory Control Module - Driver on LIN Bus

K40P Seat Memory Control Module - Passenger Lost Communication with K134P
Seat Bolster Memory Control Module - Passenger on LIN Bus

U1521

K9 Body Control Module Lost Communication with S48E Multifunction Switch -
Center Console on LIN Bus

K26 Headlamp Control Module / K28 Headlamp Leveling Control Module Lost
Communication with E13L Headlamp - Left on LIN Bus

U1522

K9 Body Control Module Lost Communication with K65 Tire Pressure Indicator
Module / B178 Tire Pressure Sensor Locator Module on LIN Bus

K26 Headlamp Control Module / K28 Headlamp Leveling Control Module Lost
Communication with E13R Headlamp - Right on LIN Bus

K33 HVAC Control Module Lost Communication with M6UR Air Temperature
Door Actuator - Right Upper Auxiliary on LIN Bus

U1523

K26 Headlamp Control Module / K28 Headlamp Leveling Control Module Lost
Communication with E13L Headlamp - Left on LIN Bus

U1524

K9 Body Control Module Lost Communication with K29 Seat Heating Control
Module / K29F Seat Heating Control Module - Front on LIN Bus

K26 Headlamp Control Module / K28 Headlamp Leveling Control Module Lost
Communication with E13R Headlamp - Right on LIN Bus

K33 HVAC Control Module Lost Communication with K10 Coolant Heater
Control Module on LIN Bus

U1525

K33 HVAC Control Module Lost Communication with K10 Coolant Heater
Control Module on LIN Bus

U1526

K9 Body Control Module Lost Communication with K29R Seat Heating Control
Module - Rear on LIN Bus

U1528

K33 HVAC Control Module Lost Communication with M37B Mode Door
Actuator - Auxiliary on LIN Bus

K40D Seat Memory Control Module - Driver Lost Communication with S64D
Seat Adjuster Switch - Driver on LIN Bus

K40P Seat Memory Control Module - Passenger Lost Communication with S64P
Seat Adjuster Switch - Passenger on LIN Bus

U152A

K33 HVAC Control Module Lost Communication with M6UL Air Temperature
Door Actuator - Left Upper Auxiliary on LIN Bus

U152B

K33 HVAC Control Module Lost Communication with K32 Steering Wheel
Heating Control Module on LIN Bus

DTC

DTC Descriptor

U152C

K9 Body Control Module Lost Communication with K18 Compass Module on
LIN Bus

U152D

K9 Body Control Module Lost Communication with P2 Transmission Shift Lever
Position Indicator on LIN Bus

K33 HVAC Control Module Lost Communication with V1 Air Ionizer on LIN Bus

U1530

K9 Body Control Module Lost Communication with M35P Window Motor
Module - Passenger / M74P Window Motor - Passenger on LIN Bus

U1531

K26 Headlamp Control Module / K28 Headlamp Leveling Control Module Lost
Communication with E13LA Headlamp Assembly - Left on LIN Bus

U1532

K26 Headlamp Control Module / K28 Headlamp Leveling Control Module Lost
Communication with E13RA Headlamp Assembly - Right on LIN Bus

U1534

K9 Body Control Module Lost Communication with M74D Window Motor -
Driver on LIN Bus

U1538

K9 Body Control Module Lost Communication with S79D Window Switch -
Driver / S146 Window/Outside Rearview Mirror Switch - Driver on LIN Bus

U153A

K9 Body Control Module Lost Communication with S79P Window Switch -
Passenger on LIN Bus

U1540

K9 Body Control Module Lost Communication with M74RR Window Motor -
Right Rear on LIN Bus

U1544

K9 Body Control Module Lost Communication with M74LR Window Motor - Left
Rear on LIN Bus

U1548

K9 Body Control Module Lost Communication with S79LR Window Switch - Left
Rear on LIN Bus

U1549

K9 Body Control Module Lost Communication with M45 Rear Wiper Motor on
LIN Bus

U154A

K9 Body Control Module Lost Communication with S79RR Window Switch -
Right Rear on LIN Bus

U154B

K9 Body Control Module Lost Communication with K49 Rear Seat Control
Module on LIN Bus

U1550

K9 Body Control Module Lost Communication with S31D Seat Heating and
Cooling Switch - Driver on LIN Bus

U1551

K9 Body Control Module Lost Communication with K33 HVAC Control Module
on LIN Bus

U1555

K9 Body Control Module Lost Communication with S100LR Seat Heating/Venting
/Cooling Switch - Left Rear on LIN Bus

U1556

K38 Chassis Control Module Lost Communication with K133 Trailer Brake Power
Control Module on LIN Bus

U1558

K9 Body Control Module Lost Communication with S31P Seat Heating and
Cooling Switch - Passenger on LIN Bus

U1559

K9 Body Control Module Lost Communication with K183 Short Range Remote
Control Transceiver on LIN Bus

U155D

K9 Body Control Module Lost Communication with S100RR Seat
Heating/Venting/Cooling Switch - Right Rear on LIN Bus

DTC

DTC Descriptor

U156D

K38 Chassis Control Module Lost Communication with S3 Transmission Shift
Lever on LIN Bus

U15E1

A11 Radio Lost Communication with A26 HVAC Controls / P17 Info Display
Module on LIN Bus

U15F0

K74 Human Machine Interface Control Module Lost Communication with P17
Info Display Module on LIN Bus

A11 Radio Lost Communication with A20 Radio/HVAC Controls / A22 Radio
Controls / P17 Info Display Module on LIN Bus

U15F1

K74 Human Machine Interface Control Module Lost Communication with K188
Human Machine Interface Control Module Bypass Module on LIN Bus

U15F3

K74 Human Machine Interface Control Module Lost Communication with K31
Navigation Control Module on LIN Bus

U1653

Chassis Systems High Speed Communication Enable Circuit

U1725

Left Headlamp High Beam Control Module Lost Communication with Left
Headlamp Low Beam Control Module

U1726

Right Headlamp High Beam Control Module Lost Communication with Right
Headlamp Low Beam Control Module

U1727

Right Headlamp High Beam Control Module Lost Communication with Right
Headlamp Leveling Actuator

U1728

Left Headlamp High Beam Control Module Lost Communication with Left
Headlamp Leveling Actuator

U1729

Right High Beam Control Module Lost Communication with Right Headlamp
Horizontal Motor

U172A

Left High Beam Control Module Lost Communication with Left Headlamp
Horizontal Motor

U1793

14V Power Module Lost Communication with Hybrid/EV Powertrain Control
Module on Powertrain Expansion Communication Bus

U1795

14V Power Module Powertrain Expansion Communication Bus Off

U179A

Lost Communication with Hybrid/EV Powertrain Control Module 2

U179C

Lost Communication with One or More Hybrid/EV Battery Interface Control
Modules

U179D

Lost Communication with Brake System Control Module 2 on Chassis Expansion
Bus

U1803

Lost Communication with Hybrid/EV Powertrain Control Module 2

U1804

Lost Communication with Inside Rearview Mirror Control Module

U1806

Battery Energy Control Module High Voltage Energy Management CAN Bus Off

U1807

Battery Charger Control Module High Voltage Energy Management CAN Bus Off

U180A

Electric A/C Compressor Control Module High Speed CAN Bus Off

U180B

Battery Energy Control Module High Speed CAN Bus Off

U180C

Battery Charger Control Module High Speed CAN Bus Off

U180D

Electronic Brake Control Module Chassis Expansion CAN Bus Off

U1811

Battery Energy Control Module Powertrain Expansion CAN Bus Off

U1814

Powertrain Wake-Up Communication Circuit

DTC

DTC Descriptor

U1815

Lost Communication with Drive Motor Control Module 1 on Bus B

U1816

Lost Communication with Drive Motor Control Module B on Bus B

U1817

Lost Communication with Hybrid/EV Powertrain Control Module on Powertrain
Expansion CAN Bus

U1818

Lost Communication with Engine Control Module on Powertrain Expansion
Communication Bus

U1821

Lost Communication with 14V Power Module on Powertrain Expansion
Communication Bus

U1826

Lost Communication with Multi-Axis Acceleration Sensor Module on Powertrain
Expansion CAN Bus

U1827

Lost Communication with Steering Angle Sensor Module on Powertrain
Expansion CAN Bus

U182A

Hybrid/EV Powertrain Control Module Lost Communication with Battery Energy
Control Module on Powertrain Expansion CAN Bus

U182D

Lost Communication with Hybrid/EV Powertrain Control Module 2 on Powertrain
Expansion Communication Bus

U182E

Drive Motor Control Module 1 Lost Communication with Hybrid/EV Powertrain
Control Module 2 on Powertrain Expansion Communication Bus

U182F

Drive Motor Control Module 2 Lost Communication with Hybrid/EV Powertrain
Control Module 2 on Powertrain Expansion Communication Bus

U1831

Drive Motor Control Module 1 Lost Communication with Hybrid/EV Powertrain
Control Module on Powertrain Expansion CAN Bus

U1833

Lost Communication with Electronic Brake Control Module on Chassis Expansion
CAN Bus

U1838

Lost Communication with Battery Charger Control Module on High Voltage
Energy Management CAN Bus

U1839

Auxiliary Transmission Fluid Pump Control Module Lost Communication with
Engine Control Module

U183A

Lost Communication with Telematics Communication Interface Control Module
on High Speed CAN Bus

U183B

Auxiliary Transmission Fluid Pump Control Module Lost Communication with
Transmission Control Module

U183C

Auxiliary Transmission Fluid Pump Control Module Lost Communication with
Hybrid/EV Powertrain Control Module 2 on Powertrain Expansion
Communication Bus

U183E

Lost Communication with Telematics Communication Interface Control Module
on Low Speed CAN Bus

U1844

Battery Energy Control Module Lost Communication with Hybrid/EV Powertrain
Control Module on Bus B

U1845

Drive Motor Control Module 1 Lost Communication with Hybrid/EV Powertrain
Control Module

U1846

Drive Motor Control Module 2 Lost Communication with Hybrid/EV Powertrain
Control Module

DTC

DTC Descriptor

U1847

Drive Motor Control Module 1 Lost Communication with Battery Energy Control
Module on Powertrain Expansion CAN Bus

U1849

Drive Motor Control Module 1 Lost Communication with Transmission Control
Module

U184A

Lost Communication with Body Control Module on Low Speed CAN Bus

U184B

Lost Communication with Remote Heater and Air Conditioning Control Module
on Low Speed CAN Bus

U184C

Lost Communication with Instrument Cluster on Low Speed CAN Bus

U184D

Lost Communication with Radio on Low Speed CAN Bus

U184E

Lost Communication with Inflatable Restraint Sensing and Diagnostic Module on
Low Speed CAN Bus

U184F

Electric A/C Compressor Control Module Lost Communication with Engine
Control Module

U1850

Drive Motor Control Module 2 Lost Communication with Transmission Control
Module

U1858

Electronic Brake Control Module Lost Communication with Hybrid/EV
Powertrain Control Module on Chassis Expansion CAN Bus

U185A

Lost Communication with Battery Energy Control Module on High Voltage Energy
Management CAN Bus

U185B

Battery Energy Control Module Lost Communication with Hybrid/EV Powertrain
Control Module 2 on High Voltage Energy Management CAN Bus

U185C

Battery Charger Control Module Lost Communication with Hybrid/EV Powertrain
Control Module 2 on High Voltage Energy Management CAN Bus

U185D

Fuel Injector Control Module Lost Communication with Engine Control Module

U185E

Fuel Injector Control Module Lost Communication with Body Control Module

U1860

Electric A/C Compressor Control Module Lost Communication with Hybrid/EV
Powertrain Control Module 2

U1861

Battery Charger Control Module Lost Communication with Engine Control
Module

U186A

Electronic Brake Control Module Lost Communication with Engine Control
Module

U186B

Electronic Brake Control Module Lost Communication with Transmission Control
Module

U1875

Drive Motor Control Module 1 Lost Communication with Battery Energy Control
Module

U1876

Drive Motor Control Module 1 Lost Communication with Engine Control Module

U1879

Drive Motor Control Module 2 Lost Communication with Engine Control Module

U1885

Battery Energy Control Module Lost Communication with Hybrid/EV Powertrain
Control Module

U1886

Battery Energy Control Module Lost Communication with Engine Control Module

U1888

Hybrid/EV Powertrain Control Module Lost Communication with Battery Energy
Control Module

DTC

DTC Descriptor

U18A1

Lost Communication with Coolant Temperature Control Module on High Voltage
Energy Management CAN Bus

U18A2

Lost Communication with Fuel Pump Driver Control Module

U18A3

Lost Communication with Human Machine Interface Control Module

U18A4

Lost Communication with Hybrid/EV Battery DC Charging Communications
Gateway Module on High Voltage Energy Management CAN Bus

U18A5

Lost Communication with Fuel Injector Control Module on Powertrain Expansion
CAN Bus

U18A6

Lost Communication with Right Object Detection Control Module on Dedicated
Bus 1

U18A7

Lost Communication with Power Supply Transformer on Powertrain Expansion
CAN Bus

U18A9

Lost Communication With Transmission Range Control Module on Chassis
Expansion CAN Bus

U18AA

Transmission Range Control Module Lost Communication with Engine Control
Module

U18AB

Transmission Range Control Module Lost Communication with Chassis Control
Module on High Speed CAN Bus

U18AC

Transmission Range Control Module Lost Communication with Chassis Control
Module on Chassis Expansion CAN Bus

U18AD

Transmission Range Control Module Lost Communication with Electronic Brake
Control Module on Chassis Expansion CAN Bus

U18AE

Lost Communication with Infotainment Control Touchpad on Dedicated Bus 1

U18AF

Lost Communications With Telematics Communications Interface Control Module
on Ethernet Bus

U18B0

Lost Communications With Instrument Cluster on Ethernet Bus

U18B1

Lost Communications With Audio Amplifier on Ethernet Bus

U18B2

Lost Communication with Rear Audio Control Module on Ethernet Bus

U18B3

Lost Communications With Navigation Control Module on Ethernet Bus

U18B4

Lost Communication with Radio on Ethernet Bus

U18B5

Lost Communication With Hybrid Powertrain Control Module on Chassis
Expansion CAN Bus

U18B6

Lost Communication with Active Safety Control Module 1 on Chassis Expansion
CAN Bus

U18B7

Lost Communication with Active Safety Control Module 2 on Chassis Expansion
CAN Bus

U18B8

Lost Communication with Body Control Module on High Speed CAN Bus

U18B9

Primary High Speed CAN Bus Subnet Configuration List

U18BA

Lost Communication with Power Steering Control Module on High Speed CAN
Bus

U18BB

Lost Communication with Power Steering Control Module on Chassis Expansion
CAN Bus

U18BF

Secondary High Speed CAN Bus Subnet Configuration List

DTC

DTC Descriptor

U18C0

Lost Communication with Suspension Control Module on High Speed CAN Bus

U18C1

Lost Communication with Suspension Control Module on Chassis Expansion CAN
Bus

U18C2

Lost Communication with Frontview Camera Module on Flexray Bus

U18C3

Lost Communication with Video Processing Control Module on High Speed CAN
Bus

U18C4

Lost Communication with Video Processing Control Module on Low Speed CAN
Bus

U18C5

Lost Communication with Electronic Brake Control Module on High Speed CAN
Bus

U18CA

Lost Communication with Active Safety Control Module 1 on Flexray Bus

U18CB

Lost Communication with Active Safety Control Module 2 on Flexray Bus

U18CC

Transmission Range Control Module Lost Communication with ECM on
Powertrain Expansion Bus

U18CF

Lost Communication with Active Safety Control Module 1 on High Speed CAN
Bus

U18D0

Lost Communication with Active Safety Control Module 2 on High Speed CAN
Bus

U18D1

Lost Communication with Transmission Range Control Module on Powertrain
Expansion CAN Bus

U18D2

Lost Communication with Transmission Range Selector Control Module on
Powertrain Sensor CAN Bus

U18D3

Lost Communication with Transmission Range Selector Control Module on
Powertrain Expansion CAN Bus

U1900

Lost Communication With Speech to Text Interface Module

U1901

Lost Communication with Infotainment Multifunction Switch Module

U2098

MOST Communication Enable Circuit

U2099

High Speed Communication Enable Circuit

U209E

Object Detection Control Module High Speed Communication Enable Circuit 1

U209F

Object Detection Control Module High Speed Communication Enable Circuit 2

U2100

CAN Bus Communication

U2101

CAN Bus Maximum List of Control Modules

U2103

Fewer Controllers On Bus Than Programmed

U2105

Lost Communication with Engine Control Module

U2106

Lost Communication with Transmission Control Module

U2107

Lost Communication with Body Control Module

U2108

Lost Communication with Electronic Brake Control Module

U2125

Lost Communication with Telematic Unit

U2127

Lost Communication with Front HVAC Control Module

U2139

Lost Communication with Column Integration Module

U2144

Lost Communication with Distance Sensing Cruise Control Module

U216A

Lost Communication with Front Object Detection Control Module

DTC

DTC Descriptor

U216B

Lost Communication with Rear Object Detection Control Module

U2176

Lost Communication with Power Take-Off Control Module

U2178

Lost Communication With Trailer Interface Control Module

U2400

Fuel Injector Control Module High Speed CAN Bus Off

U2401

Battery Energy Control Module Dedicated Bus 1 Off

U2409

Transmission Range Control Module High Speed CAN Bus Off

U240A

Transmission Range Control Module Chassis Expansion CAN Bus Off

U240B

Radio Dedicated Bus Off

U240D

Transmission Range Selector Control Module Powertrain Expansion CAN Bus Off

U240E

Transmission Range Selector Control Module Powertrain Sensor CAN Bus Off

U240F

Transmission Range Control Module Lost Communication with EBCM on High
Speed CAN Bus

U2410

Transmission Range Control Module Lost Communication with BCM on High
Speed CAN Bus

U2411

Transmission Range Control Module Powertrain Expansion CAN Bus Off

U2412

Reductant Control Module Powertrain Sensor Bus Off

U2501

Invalid Data Received From Hybrid/EV Powertrain Control Module 2

U2502

Invalid Data Received From Electronic Brake Control Module on Chassis
Expansion CAN Bus

U2503

Invalid Data Received From Object Detection Control Module

U2504

Invalid Data Received From Trailer Brake Driver Control Module

U2505

Invalid Data Received from Human Machine Interface Control Module on MOST
Bus

U2506

Invalid Data Received From Dual Battery Control Module

U2507

Invalid Data Received from Instrument Cluster on MOST Bus

U2508

Invalid Data Received from Audio Amplifier on MOST Bus

U250B

Invalid Data Received from Active Safety Control Module 1 on Chassis Expansion
CAN Bus

U250C

Invalid Data Received from Active Safety Control Module 2 on Chassis Expansion
CAN Bus

U250D

Invalid Data Received from Transmission Control Module on Chassis Control

Module LIN Bus 2

U250E

Invalid Data Received from Vehicle Dynamic Sensor 1

U250F

Invalid Data Received from Vehicle Dynamic Sensor 2