OnStar 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 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, repair open/high resistance 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. Verification Tests

* Mobile Telephone Microphone Replacement