Radio Controls Malfunction

Radio Controls Malfunction

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.

* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Diagnostic Fault Information






Circuit/System Description

The radio/HVAC controls is a separate component from the radio, combined into an assembly. The assembly contains the radio control knobs and buttons for all audio and HVAC functions and the information display. The assembly is supplied battery voltage and ground. The radio uses the wake up circuit to control the power state of the display. The radio controls communicate inputs internally to the display. Display backlighting dimming level, graphical data, and radio control inputs are communicated over the CGI serial data circuits between the display and the radio.

Communications between the HVAC controls and the HVAC control module are on a separate LIN circuit. The HVAC control module communicates status information to the radio via GMLAN for HVAC information display.

Reference Information

Schematic Reference

Radio/Navigation System Schematics Radio/Navigation System Schematics

Connector End View Reference

Component Connector End Views Fuel Pump and Level Sensor Assembly - Primary

Description and Operation

Radio/Audio System Description and Operation Radio/Audio System

Electrical Information Reference

* Circuit Testing Circuit Testing

* Connector Repairs Connector Repairs

* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections

* Wiring Repairs Wiring Repairs

Scan Tool Reference

Control Module References Control Module References for scan tool information

Circuit/System Verification

1. Ignition ON, A11 radio ON.

2. Verify DTC U0257 is not set.

• If DTC U0257 is set
Refer to Radio Information Display Malfunction - DTC U0257 U0257.

• If DTC U0257 is not set

3. Verify DTC B1020 is not set.

• If DTC B1020 is set
Refer to DTC B1020 B1020.

• If DTC B1020 is not set

4. Verify the information display module turns on and information is shown on the display.

• If the information display malfunctions.
Refer to Radio Information Display Malfunction - DTC U0257 U0257.

• If the info display module turns on and information is shown on the display.

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

• If some, but not all, controls operate normally.
Replace the A20 radio/HVAC controls.

• If all radio controls operate and perform the correct function.

6. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the repair.

Radio Control Assembly Replacement Radio Control Assembly Replacement