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 are supplied battery voltage and ground. The radio controls the power state of the controls via a wake up circuit. Communications between the radio controls and the radio are through the CGI serial data circuits.
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.
Reference Information
Schematic Reference
Radio/Navigation System Schematics Radio/Navigation System Schematics
Connector End View Reference
Component Connector End Views Hybrid/EV Battery Pack X1
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 Programming and Relearning for scan tool information
Circuit/System Verification
1. Vehicle in Service Mode, radio ON.
2. Verify that all radio/HVAC 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 controls operate and perform the correct function.
3. All OK.
Circuit/System Testing
1. Vehicle 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. Vehicle 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. Test for less than 20 ohms between the data shield circuit terminal 3 and ground.
• If 20 ohms or greater
1. Vehicle OFF, disconnect the X1 connector at the A11 radio.
2. Test for less than 2 ohms in the data shield circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the A11 radio.
• If less than 20 ohms
4. 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. Vehicle 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. Vehicle OFF.
2. 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, replace the A20 radio/HVAC controls.
• If the test lamp illuminates.
5. Vehicle in Service Mode.
6. Test for 2-3 V between the serial data circuit terminals listed below and ground.
* terminal 1
* terminal 2
• If less than 2 V
1. Vehicle OFF, disconnect the X1 harness connector at the A11 radio.
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 A11 radio.
• If greater than 3 V
1. Vehicle OFF, disconnect the X1 harness connector at the A11 radio. Vehicle in Service Mode.
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 A11 radio.
• If between 2-3 V
7. Test for less than 1 V between the control circuit terminals listed below and ground.
* terminal 4
* terminal 15
• If greater than 1 V
1. Vehicle OFF, disconnect the X1 harness connector at the A11 radio. Vehicle in Service Mode.
2. Test for less than 1 V between the control circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the A11 radio.
• If less than 1 V
8. Vehicle OFF, disconnect the X1 harness connector at the A11 radio.
9. Test for infinite resistance between the control circuit terminals listed below and ground.
* A20 radio/HVAC controls terminal 4
* A20 radio/HVAC controls terminal 15
• If less than infinite resistance,
Repair the short to ground on the circuit.
• If infinite resistance
10. Test for less than 2 ohms between the control circuits listed below.
* A20 radio/HVAC controls terminal 4 and the A11 radio terminal 13 X1
* A20 radio/HVAC controls terminal 15 and the A11 radio terminal 27 X1
• If 2 ohms or greater
Repair the open/high resistance in the circuit.
• If less than 2 ohms.
11. Replace the A20 radio/HVAC controls. Connect all harness connectors.
12. Vehicle in Service Mode, radio ON.
13. Verify that all radio controls operate and perform the correct function.
• If the radio controls still malfunction.
Replace the A11 radio.
• If all radio controls operate and perform the correct function.
14. All OK
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
Control Module References Programming and Relearning for radio or radio control assembly replacement, programming, and setup.