Operation CHARM: Car repair manuals for everyone.
Home >> Cadillac Truck >> 2012 >> SRX AWD V6-3.6L >> Repair and Diagnosis >> Accessories and Optional Equipment >> Testing and Inspection >> Symptom Related Diagnostic Procedures >> Radio Controls Malfunction (with Color Display)

Radio Controls Malfunction (with Color Display)




Radio Controls Malfunction (with Color 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 Instructionsprovides an overview of each diagnostic category.

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 for HVAC information display.

Reference Information
Schematic Reference

Radio/Navigation System Schematics Radio/Navigation System Schematics
Connector End View Reference

Component Connector End Views Connector End Views By Name
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 Referencesfor scan tool information

Circuit/System Verification

1. Verify no DTCs are set as current.

• If any DTCs are set as current, refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle.

2. Ignition ON, radio ON, verify the radio/HVAC controls backlighting illuminates and that all controls perform the correct function.

• If some, but not all, controls operate normally, replace the radio/HVAC control.
• If all controls are inoperative, refer to Circuit/System Testing.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the A20 radio/HVAC controls.
2. Test for less than 10 ohm between the ground circuit terminal 17 and ground.

• If greater than the specified range, test the ground circuit for an open/high resistance.

3. Test for less than 20 ohm between the data shield circuit terminal 3 and ground.

• If greater than the specified range, test the ground circuit for an open/high resistance. If the circuit tests normal, replace the A11 radio.

4. Verify that a test lamp illuminates between the B+ circuit terminal 10 and ground.

• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.

5. Ignition ON, test for 2.4-2.75 V between the data circuit terminal 1 and ground.

• If less than the specified range, test the data circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the A11 radio.
• If greater than the specified range, test the data circuit for a short to voltage. If the circuit tests normal, replace the A11 radio.

6. Test for 2.4-2.75 V between the data circuit terminal 2 and ground.

• If less than the specified range, test the data circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the A11 radio.
• If greater than the specified range, test the data circuit for a short to voltage. If the circuit tests normal, replace the A11 radio.

7. Test for less than 1 V between the wake signal terminal 4 and ground.

• If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the A11 radio.

8. Test for less than 1 V between the reset signal terminal 15 and ground.

• If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the A11 radio.

9. Ignition OFF, reconnect the harness connector at the A20 radio/HVAC controls.
10. Disconnect the X1 harness connector at the A11 radio.
11. Install a DMM between wake signal terminal 13 and ground.
12. Ignition ON, verify the DMM reading is 4.5-5.5 V DC.

• If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the A20 radio/HVAC controls.
• If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the A20 radio/HVAC controls.

13. Press the power button on the radio controls. Verify the DMM reading is momentarily less than 1 V and returns to 4.5-5.5 V DC each time the power button is pressed.

• If not the specified value, replace the A20 radio/HVAC controls.

14. Test for 4.5-5.5 V between the reset signal terminal 27 and ground.

• If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the A20 radio/HVAC controls.
• If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the A20 radio/HVAC controls.

15. If all circuits test normal, replace the A20 radio/HVAC controls and reconnect all harness connectors.
16. Ignition ON, radio ON, verify the radio/HVAC controls backlighting illuminates and that all controls perform the correct function.

• If the radio/HVAC controls are still inoperative, replace the A11 radio.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests.

* Heater and Air Conditioning and Radio Control Module Replacement Service and Repair
* Control Module References Control Module Referencesfor radio replacement, setup, and programming.

pro multis · About Operation CHARM