For 1990-2009 cars only
Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure |
| • | 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® vehicle communication interface module (VCIM) recieves an audio input signal from the cellular microphone.
Reference Information
Schematic Reference
Connector End View Reference
Entertainment/Communication Connector End Views
Description and Operation
OnStar Description and Operation
Electrical Information Reference
| • | Circuit Testing |
| • | Wiring Repairs |
Circuit/System Verification
Important: Perform this diagnostic if the OnStar® Call Center operator can clearly be heard but the operator is unable to hear the caller.
Ignition ON, press OnStar® Call button. Verify that your voice cannot be heard clearly by the OnStar® Call Center.
| ⇒ | If your voice can be heard clearly, go to Testing for Intermittent Conditions and Poor Connections . |
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the inside rearview mirror.
- Ignition ON, test for greater than 9 volts between the cellular microphone signal circuit terminal 10 and ground.
- Test for greater than 9 volts between the cellular microphone signal circuit terminal 10 and the drain circuit terminal 2.
- If all circuit test normal, test or replace the cellular microphone assembly.
| ⇒ | 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. |
| ⇒ | If less than specified value, test the drain wire for an open/high resistance. If the circuit tests normal, replace the VCIM. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for VCIM replacement, setup, and programming
