GM Service Manual Online
For 1990-2009 cars only

Important: Never swap OnStar® vehicle integration units (VIU), or the vehicle communication units (VCU) from other vehicles. Transfer of OnStar® components from other vehicles should NOT be done. Each OnStar® component has a unique identification number. The VIU has a 10-digit specific station identification (STID) and the VCU has a 11-digit specific electronic serial number (ESN). These identification numbers are used by the National Cellular Telephone Network and OnStar® systems, and are stored in the General Motors vehicle history files by VIN.

Removal Procedure

  1. Remove the top cover of the body side trim panel on the right side of the vehicle to expose the VCU/VIU assembly.

  2. Object Number: 655250  Size: SH
  3. Disconnect the cellular antenna coaxial cable (2) and electrical connector (6) from the VCU (7).
  4. Detach the steel retainer (8) to release the VCU (7) from the VCU/VIU assembly.
  5. Remove the VCU from the vehicle.
  6. The old VCU must be returned for core credit.

Installation Procedure

  1. Record the 11-digit ESN from the label on the new VCU module.

  2. Object Number: 655250  Size: SH
  3. Install the VCU (7) to the vehicle.
  4. Install the VCU (7) to the VCU/VIU assembly mounting bracket ensuring that the steel retainer (8) is securely fastened.
  5. Reconnect the cellular antenna coaxial cable (2) and electrical connector (6) to the VCU.
  6. Install the top cover of the body side trim panel to cover the VCU/VIU assembly.
  7. Reconfigure the OnStar® system. Refer to OnStar Reconfiguration .
  8. The 11-digit ESN number will be needed by the OnStar® advisor.