Radio Controls Malfunction (with Monochrome Display)
Radio Controls Malfunction (with Monochrome Display)
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 controls and information display are separate components from the radio. Each component 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 with the info display module through the LIN serial data circuit. Display backlighting dimming level, graphical data, and radio control inputs are communicated over the CGI 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 Sunshade - Left Front
Description and Operation
Radio/Audio System Description and Operation (with Monochrome Display) Radio/Audio System Description and Operation (with Monochrome Display)Radio/Audio System Description and Operation (with Color Display) Radio/Audio System Description and Operation (with Color Display)
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. Verify no DTCs are present.
• If any DTCs are present.
Refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle.
• If no DTCs are present.
2. Ignition ON, A11 radio ON.
3. 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 controls are inoperative.
Refer to Circuit/System Testing
• If all radio controls operate and perform the correct function.
4. All OK.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the A20 radio/HVAC controls.
2. Test for less than 10 ohms between the ground circuit terminal 17 and ground.
• If 10 ohms or greater
1. Ignition OFF.
2. Test for less than 2 ohms in the ground circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, repair the open/high resistance in the ground connection.
• If less than 10 ohms
3. Verify that a test lamp illuminates between the B+ circuit terminal 10 and ground.
• If the test lamp does not illuminate and the circuit fuse is good.
1. Ignition OFF.
2. Test for less than 2 ohms in the B+ circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, refer to Power Mode Mismatch Power Mode Mismatch.
• If the test lamp does not illuminate and the circuit fuse is open.
1. Ignition OFF.
2. Disconnect the harness connector at the P17 info display module.
3. Test for infinite resistance between the B+ circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance.
4. Connect the harness connector at the P17 info display module.
5. Test for greater than 10 ohms between the B+ circuit and ground.
• If less than 10 ohms, replace the P17 info display module.
• If 10 ohms or greater, replace the A20 radio/HVAC controls.
• If the test lamp illuminates.
4. Ignition ON.
5. Test for 2-11.5 V between the serial data circuit terminal 7 and ground.
• If less than 2 V
1. Ignition OFF, disconnect the X1 harness connector at the P17 info display module.
2. Test for infinite resistance between the serial data circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test for less than 2 ohms in the serial data circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the P17 info display module.
• If greater than 11.5 V
1. Ignition OFF, disconnect the X1 harness connector at the P17 info display module. Ignition ON.
2. Test for less than 1 V between the serial data circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the P17 info display module.
• If between 2-11.5 V
6. Test or replace the A20 radio/HVAC controls.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Radio Control Assembly Replacement Radio Control Assembly Replacement
* Driver Information Display Replacement Service and Repair
* Control Module References Control Module References for radio replacement, programming, and setup.