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.
* ReviewStrategy 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.
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 remote playback device audio signal circuit, and returned to the module on the remote playback device 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) Center Call button.
3. 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 radio and the X2 harness connector at the CIM.
2. Verify that a test lamp does not illuminate between B+ and the CIM X2 harness connector terminal 1.
• If the test lamp illuminates, test the signal circuit for a short to ground.
3. Verify that a test lamp does not illuminate between B+ and the CIM X2 harness connector terminal 2.
• If the test lamp illuminates, test the signal circuit for a short to ground.
4. Test for less than 1 ohm between the CIM X2 harness connector terminal 1 and the radio X2 harness connector terminal 7.
• If greater than the specified range, test the circuit for a short to voltage or an open/high resistance.
5. Test for less than 1 ohm between the CIM X2 harness connector terminal 2 and the radio X2 harness connector terminal 15.
• If greater than the specified range, test the circuit for a short to voltage or an open/high resistance.
6. Reconnect the CIM X2 harness connector.
7. Ignition ON, test for a momentary AC voltage between the signal circuit radio X2 harness connector terminal 7 and the signal return circuit terminal 15 when the white dot button on the OnStar keypad is pressed.
• If AC voltage was not present, replace the CIM.
8. If all circuits test normal, replace the radio.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
Control Module References (Programming and Relearning) for radio or CIM replacement, setup, and programming.