OnStar Microphone Inoperative - Caller Cannot Be Heard

OnStar Microphone Inoperative - Caller Cannot Be Heard

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.



Circuit/System Description

The OnStar(R) vehicle communication interface module (VCIM) receives an audio input signal from the cellular microphone.


Reference Information
Schematic Reference

OnStar Schematics (OnStar 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

Programming and Relearning (Programming and Relearning)for scan tool information


Circuit/System Verification

Ignition ON, press OnStar(R) Call button. Verify that your voice cannot be heard clearly by the OnStar(R) Call Center.


Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the cellular microphone.
2. Ignition ON, test for greater than 9 volts between the signal circuit terminal B and ground.

• If less than specified value, test the cellular microphone signal circuit for a short to ground, open/high resistance. If the circuit tests normal, replace the VCIM.

3. Test for greater than 9 volts between the cellular microphone signal circuit terminal B and the drain circuit terminal A.

• If less than specified value, test the drain wire for an open/high resistance. If the circuit tests normal, replace the VCIM.

4. If all circuit test normal, test or replace the cellular microphone assembly.



Repair Instructions

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

* Mobile Telephone Microphone Replacement (Service and Repair)
* Programming and Relearning (Programming and Relearning)for VCIM replacement, setup, and programming