Microphone Inoperative - Caller Cannot Be Heard

OnStar Microphone Inoperative - Caller Cannot Be Heard

Diagnostic Instructions

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

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 terminal B and ground.

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

3. Test for greater than 9 volts between the terminal B and the terminal A.

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

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

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

* Mobile Telephone Microphone Replacement (with Sunroof) Mobile Telephone Microphone Replacement (without Sunroof)
* Control Module References for VCIM replacement, setup, and programming Verification Tests