No (or Noisy) OnStar Audio

No (or Noisy) OnStar Audio

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.

Diagnostic Fault Information





Circuit/System Description

When an OnStar(R) keypress is made, a serial data message is sent to the audio system to mute all radio functions and output OnStar(R) originated audio. After the audio system is muted, the communication interface module (CIM) transmits signals to the audio system on the audio signal circuit, and returned to the module on the audio common signal circuit.

Reference Information
Schematic Reference

* OnStar Schematics (OnStar Schematics)
* Radio/Navigation System Schematics (Radio/Navigation System Schematics)

Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

OnStar Description and Operation (OnStar Description and Operation)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Control Module References (Programming and Relearning) 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.

• If audio is not heard clearly, refer to Speaker Malfunction (Speaker Malfunction).

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

• If OnStar(R) message is noisy or distorted, refer to Circuit/System Testing.

Circuit/System Testing

1. Ignition OFF, disconnect the X2 harness connector at the CIM.
2. Test for less than 5 Ohms between terminal 2 and ground.

• If greater than the specified range, test the circuit for an open or high resistance. If the circuit tests normal, replace the audio amplifier.

3. Reconnect the CIM X2 harness connector. Disconnect the X2 harness connector at the audio amplifier.
4. Ignition ON, test for a momentary AC voltage between the signal circuit terminal B12 and ground when the OnStar(R) Call Center button is pressed.

• If AC voltage was not present, test the circuit for a short to voltage, short to ground, or an open/high resistance. If the circuit tests normal, replace the CIM.

5. If all circuits test normal, replace the audio amplifier.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

Control Module References (Programming and Relearning) for amplifier or CIM replacement, setup, and programming.