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.

1. Remove the rear compartment trim. Refer to Rear Compartment Trim Panel Replacement .
2. Remove the coax cable (1) from the VCU module (3).
3. Disconnect the electrical connectors.
4. Remove the VCU module from the bracket assembly.
5. The old VCU must be returned for core credit.

1. Record the 11-digit ESN number from the label on the new part.



2. Install the VCU module onto the bracket assembly.
3. Connect the coax cable (3) to the VCU (3).
4. Reconfigure the OnStar® system. Refer to OnStar Reconfiguration .

The 11-digit ESN number will be needed by the OnStar® advisor.

5. Install the rear compartment trim. Refer to Rear Compartment Trim Panel Replacement .