OnStar Microphone Malfunction

OnStar Microphone 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)provide an overview of each diagnostic category.

Diagnostic Fault Information





Circuit/System Description

Without RPO UAV

The communication interface module (CIM) uses the cellular phone microphone to allow driver communication with OnStar.

With RPO UAV

The communication interface module (CIM) and navigation radio use the cellular phone microphone to allow driver communication with OnStar, as well as to operate the voice recognition/voice guidance feature of the navigation radio.

Reference Information
Schematic Reference

OnStar Schematics (OnStar Schematics)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
Description and Operation

OnStar Description and Operation (OnStar)
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)

Circuit/System Testing

Without RPO UAV
1. Ignition OFF, disconnect the harness connector at the cellular microphone.
2. Ignition OFF, test for less than 5 ohms between the low reference circuit terminal A and ground.

• If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the CIM.

3. Ignition ON, test for 9-11 volts between the signal circuit terminal B and ground.

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

4. If all circuits test normal, replace the cellular microphone.

With RPO UAV
1. Ignition OFF, disconnect the X4 harness connector at the navigation radio and the harness connector at the cellular microphone.
2. Ignition OFF, test for less than 5 ohms between the low reference circuit terminal A and ground.

• If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the CIM.

3. Ignition ON, test for 9-11 volts between the signal circuit terminal B and ground.

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

4. If all circuits test normal, replace the cellular microphone.
5. Connect the X4 harness connector at the navigation radio. Verify DTC B2455 is not set as current in the navigation radio.

• If DTC B2455 is set as current, replace the navigation radio.

Repair Instructions

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

* Mobile Telephone Microphone Replacement (Service and Repair)
* Control Module References (Programming and Relearning)for CIM or navigation radio replacement, setup, and programming