Chevrolet Trax: DTC U0255-U0257: Lost communication with info display

Diagnostic Instructions

• Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
• Review Strategy Based Diagnosis for an overview of the diagnostic approach.
• Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC U0255

Lost Communication with Info Display Module

DTC U0256

Lost Communication with Infotainment Faceplate Control Module

DTC U0257

Lost Communication with Info Display Module/Infotainment Faceplate Control Module

Circuit/System Description

The radio information display and controls are separate components from the radio. One or more configurations may be possible, dependent upon the available content for the vehicle. The DTC(s) that can set when a malfunction occurs can vary due to calibration differences required for the vehicle content.

Diagnosis of these communication DTCs is based upon the symptom observed in the vehicle.

Monochrome Displays

When the vehicle is equipped with a monochrome display, the radio and the display communicate with each other via CGI serial data. The radio controls communicate with the display via LIN communications, and the control messages are passed through to the radio.

When the display and controls are combined in an assembly, the communication between the two components occurs within the assembly. If the two components are separate, the communication between the display and the controls is external, via the wiring harness.

Color Displays

When the vehicle is equipped with a color display, the display and controls communicate individually with the radio. The radio communicates directly with the controls via CGI serial data. A dedicated video cable is used to communicate graphical information between the radio and the display.

For non-touch color displays, a dedicated dimming circuit is used. The radio provides an output to the display based on dimming level information the radio receives.

Touch screen color displays use touch serial data communication between the display and the radio to exchange touch data, backlighting, and dimming levels.

Diagnostic Aids

• When equipped with a monochrome display, if the display is inoperative, the main radio controls will also be inoperative.
• The functions available on the steering wheel controls (if equipped) will continue to operate if the main radio controls are inoperative.
• The DTC may be stored as a history DTC without affecting the operation of the display or controls.

Reference Information

Schematic Reference

Radio/Navigation System Schematics (Encore), Radio/Navigation System Schematics (Trax)

Connector End View Reference

WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - ENCORE WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - TRAX

Description and Operation

Radio/Audio System Description and Operation (with Monochrome Display), Radio/Audio System Description and Operation (with Color Display)

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

1. Ignition ON, A11 Radio ON.
2. Verify the P17 Info Display Module turns on and information is shown on the display.

If the P17 Info Display Module does not turn on, or information is not shown in the display.

• If the P17 Info Display Module turns on and information is shown on the display.

3. Verify that all radio controls operate and perform the correct function.

• If some, but not all, controls operate normally.

Replace the appropriate A20 Radio/HVAC Controls or the A22 Radio Controls.

• If all controls are inoperative.

Refer to Radio Controls Malfunction (Monochrome Display), Radio Controls Malfunction (Color Display).

• If all controls operate and perform the correct function.

4. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

• Control Module References for replacement, programming, and setup.

SYMPTOMS - CELLULAR COMMUNICATION

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

1. Perform the Diagnostic System Check - Vehicle before using the Symptom Tables in order to verify that all of the following are true:

• There are no DTCs set.
• The control modules can communicate via the serial data link.

2. Review the system operation in order to familiarize yourself with the system functions. Refer to OnStar Description and Operation.

Visual/Physical Inspection

• Inspect for aftermarket devices which could affect the operation of the Radio/Audio System. Refer to Checking Aftermarket Accessories .
• Inspect for easily accessible or visible system components for obvious damage or conditions which could cause the symptom.

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 (OnStar), Bluetooth Malfunction (Radio - Without UH7), Bluetooth Malfunction (Radio - With UH7)
• 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.

1. Perform the Diagnostic System Check - Vehicle before using the Symptom Tables in order to verify that all of the following are true:

• There are no DTCs set.
• The control modules can communicate via the serial data link.

2. Review the system operation in order to familiarize yourself with the system functions. Refer to Radio/Audio System Description and Operation (with Monochrome Display), Radio/Audio System Description and Operation (with Color Display).

Visual/Physical Inspection

• Inspect for aftermarket devices which could affect the operation of the Radio/Audio System. Refer to Checking Aftermarket Accessories .
• Inspect for easily accessible or visible system components for obvious damage or conditions which could cause the symptom.

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 (OnStar), Bluetooth Malfunction (Radio - Without UH7), Bluetooth Malfunction (Radio - With UH7)
• Digital Radio Poor or No Reception
• Navigation System - Voice Recognition Malfunction
• No Global Positioning System (GPS) Reception
• Radio Controls Malfunction (Monochrome Display), Radio Controls Malfunction (Color Display)
• Radio Information Display Malfunction (Monochrome Display), Radio Information Display Malfunction (Color Display)
• Radio Poor Reception
• Speaker Malfunction

SYMPTOMS - ENTERTAINMENT

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

1. Perform the Diagnostic System Check - Vehicle before using the Symptom Tables in order to verify that all of the following are true:

• There are no DTCs set.
• The control modules can communicate via the serial data link.

2. Review the system operation in order to familiarize yourself with the system functions. Refer to Radio/Audio System Description and Operation (with Monochrome Display), Radio/Audio System Description and Operation (with Color Display).

Visual/Physical Inspection

• Inspect for aftermarket devices which could affect the operation of the Radio/Audio System. Refer to Checking Aftermarket Accessories .
• Inspect for easily accessible or visible system components for obvious damage or conditions which could cause the symptom.

Intermittent

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

Symptom List

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

• Application Malfunction
• Auxiliary Audio Input Malfunction
• Bluetooth Malfunction (OnStar), Bluetooth Malfunction (Radio - Without UH7), Bluetooth Malfunction (Radio - With UH7)
• Digital Radio Poor or No Reception
• Radio Controls Malfunction (Monochrome Display), Radio Controls Malfunction (Color Display)
• Radio Information Display Malfunction (Monochrome Display), Radio Information Display Malfunction (Color Display)
• Radio Poor Reception
• Speaker Malfunction

APPLICATION MALFUNCTION

Diagnostic Instructions

• Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
• Review Strategy Based Diagnosis for an overview of the diagnostic approach.
• Diagnostic Procedure Instructions provide an overview of each diagnostic category.

Circuit/System Description

The term application refers to any piece of software that works on a system (hardware) that is being operated by its 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

• For an application to be used, it must be installed on both the vehicle infotainment system and a compatible mobile device.
• The application must work correctly on the device to work with the vehicle infotainment system.
• The user may be required to log-in to the application on the mobile device before using the application from the vehicle controls.
• Applications use the mobile device and connection to a service provider to operate. Connection quality issues, or service provider data transmission issues can give the appearance of a vehicle malfunction.
• The device must be connected to the system. This may be done wirelessly via Bluetooth , or via the vehicle USB port.

When a mobile device is connected via Bluetooth, 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.

• The device must be unlocked, and any additional applications should be closed.
• If the device has any sound enhancement features such as noise reduction or echo control, these features should be turned off.
• A low battery condition in the mobile device may not allow the device to connect to the system, or can create communication issues with the device. Verify the device battery state of charge and re-charge or replace as needed.
• If a 'Please See Device' or similar type error message is displayed, this may indicate the device has lost its connection to the vehicle, or the device has lost its external data connection.
• If a cable is used for connection, attempt to connect the device using a different cable; cables can deteriorate over time or become damaged.

Reference Information

Schematic Reference

Radio/Navigation System Schematics (Encore), Radio/Navigation System Schematics (Trax)

Connector End View Reference

WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - ENCORE WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - TRAX

Description and Operation

Radio/Audio System Description and Operation (with Monochrome Display), Radio/Audio System Description and Operation (with Color Display)

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

1. Verify the application is installed on the mobile device and is up to date.

• If the application is not installed or is not up to date.

Install or update the application on the device.

• If the application is installed on the mobile device and is up to date

2. Verify the application operates correctly on the mobile device.

• If the application is not operating correctly on the mobile device.

Refer to the application website.

• If the application is operating correctly on the mobile device.

3. Verify the A11 Radio calibrations are current.

• If the radio calibrations are not current

Reprogram the A11 Radio and re-evaluate the concern.

• If no update calibrations are available

4. Verify the application is installed on the A11 Radio and is up to date.

• If the application is not installed or is not up to date.

Install or update the application on the A11 Radio.

• If the application is installed on the A11 Radio and is up to date

5. Ignition ON, A11 Radio ON.
6. Verify the mobile device can connect to the infotainment system. Refer to the owners manual for information on the preferred connection method for the device.

If the mobile device cannot connect to the vehicle infotainment system.

• If unable to connect via Bluetooth, refer to Bluetooth Malfunction (OnStar), Bluetooth Malfunction (Radio - Without UH7), Bluetooth Malfunction (Radio - With UH7).
• If unable to connect via USB, refer to Auxiliary Audio Input Malfunction.

If the mobile device connects to the vehicle infotainment system.

7. Launch the application.
8. Verify the applications operates properly with the vehicle infotainment system.

• If the application does not function properly

Refer to diagnostic aids.

• If the application functions properly

9. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

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

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