GM Service Manual Online
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 CIM is capable of interpreting voice commands recieved over the cellular microphone circuits. Speech recognition allows the user to speak to one computer in the vehicle, and one reached over the cellular communication network. The module attempts to understand the users command, and responds by speaking back, or by taking the appropriate action, e.g. dialing the phone.

Reference Information

Schematic Reference

OnStar Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

OnStar Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Circuit/System Verification

Important: 

   • It is necessary to have the vehicle in an open outside area where a cellular call can be successfully placed and GPS data can be received from satellites.
   • The vehicle should be located in a quiet area.

  1. Ignition ON, press OnStar® Call button. Verify that your voice is heard clearly by the OnStar® Call Center.
  2. If your voice can not be heard clearly, refer to OnStar Microphone Inoperative - Caller Cannot Be Heard.
  3. Press the OnStar® Call answer button. Attempt to operate the OnStar® system using multiple different voice commands. Verify the system responds appropriately to all voice commands.
  4. If the OnStar® system does not respond to any voice commands, replace the CIM.
  5. If the system is operational, but does not respond appropriately to certain commands refer to OnStar Description and Operation for tips on proper pronunciation.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for VCIM replacement, setup, and programming