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 electrical component mounting bracket nuts (2).
3. Pull the electrical component mounting bracket (1) away from the body and place the electrical component mounting bracket (1) module side up in the rear compartment.



4. Disconnect the electrical connection and the coaxial antenna cable from the VCU (2).
5. Slide the VCU out of the mounting bracket (1).
6. The old VCU must be returned for core credit.

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



2. Slide the VCU (2) into the mounting bracket (1).

Notice: In order to avoid damage to the circuit board, do NOT over-tighten the thumb screws. Using your fingers, apply only a light pressure.

3. Connect the electrical connector.

Apply 0.2 N·m (2 lb in) of torque, or less, to the VIU thumb screw electrical connections.

4. Connect coaxial antenna cable to the VCU (2).



5. Push in on the top of the module assembly until an audible click is heard. This click indicates that the mounting tab (1) has fastened the VIU/VCU securely to the electrical component mounting bracket.
6. Install the electrical component mounting bracket (1) to the vehicle body.

Notice: Refer to Fastener Notice in the Preface section.




7. Install the electrical component mounting bracket nuts (2).

Tighten
Tighten the nuts to 9 N·m (80 lb in).

8. Install the rear compartment trim. Refer to Rear Compartment Trim Panel Replacement .
9. Reconfigure the OnStar® system. Refer to OnStar Reconfiguration .

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