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OnStar Audio Malfunction

OnStar Audio 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 provides an overview of each diagnostic category.


Diagnostic Fault Information

Circuit Short to Ground Open/High Resistance Short to Voltage Signal Performance
Audio Signal 1 1 1 -
Audio Common Signal - 1 - -
1. No (or Noisy) OnStar® Audio


Circuit/System Description

When an OnStar® keypress is made, a serial data message is sent to the audio system to mute all radio functions and output OnStar® originated audio. After the audio system is muted, the telematics communication interface control module transmits signals to the audio system on the audio signal and audio common circuits.

Reference Information

Schematic Reference


• OnStar Schematics

• Radio/Navigation System Schematics


Connector End View Reference

Component Connector End Views

Description and Operation

OnStar Description and Operation

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. Tune radio to a known good station and verify the audio is heard clearly through all speaker channels.

2. If audio is not heard clearly, refer to Speaker Malfunction .

3. Ignition ON, radio ON, set volume to comfortable level and press OnStar® Call Center button. Verify Connecting to OnStar® message is heard clearly through the audio system.

4. If OnStar® message is noisy or distorted, refer to Circuit/System Testing.


Circuit/System Testing


1. Ignition OFF, disconnect the X1 harness connector at the radio.

2. Disconnect the X2 harness connector at the K73 telematics communication interface control module.

3. Ignition ON, test for less than 1 V between the K73 telematics communication interface control module cellular telephone voice signal circuit terminal 1 X2 and ground.

4. If not the specified value, test the cellular telephone voice signal circuit for a short to voltage.

5. Test for less than 1 V between the K73 telematics communication interface control module cellular telephone voice low reference circuit terminal 2 X2 and ground.

6. If not the specified value, test the cellular telephone voice low reference circuit for a short to voltage.

7. Ignition OFF, test for infinite resistance between the K73 telematics communication interface control module cellular telephone voice signal circuit terminal 1 X2 and ground.

8. If not the specified value, test the cellular telephone voice signal circuit for a short to ground.

9. Test for infinite resistance between the K73 telematics communication interface control module cellular telephone voice low reference circuit terminal 2 X2 and ground.

10. If not the specified value, test the cellular telephone voice low reference circuit for a short to ground.

11. Test for less than 2 Ω between the K73 telematics communication interface control module cellular telephone voice signal circuit terminal 1 X2 and the radio terminal 20 X1.

12. If not the specified value, test the cellular telephone voice signal circuit for a open/high resistance.

13. Test for less than 2 Ω between the K73 telematics communication interface control module cellular telephone voice low reference circuit terminal 2 X2 and the radio terminal 6 X1.

14. If not the specified value, test the cellular telephone voice low reference circuit for a open/high resistance.

15. If all circuits test normal, replace the K73 telematics communication interface control module.

16. If all circuits test normal, replace the radio.


Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for radio or telematics communication interface control module replacement, setup, and programming.