OnStar Microphone Inoperative - Caller Cannot Be Heard

OnStar Microphone Inoperative - Caller Cannot Be Heard

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)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 (Component Connector End Views)
Description and Operation

OnStar Description and Operation (OnStar Description and Operation)
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)

Scan Tool Reference

Control Module References (Control Module References)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)
* Control Module References (Control Module References)for VCIM replacement, setup, and programming