For 1990-2009 cars

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 windshield garnish molding. Refer to Windshield Pillar Garnish Molding Replacement .
2. Remove the upper trim pad. Refer to Instrument Panel Upper Trim Pad Replacement .
3. Remove the clip-on strap which secures the VCU to the bracket (1).
4. Disconnect the electrical connectors.
5. Disconnect the cell antenna coaxial cable (1) from the VCU (2).
6. Remove the VCU (2) from the bracket.
7. 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. Install the VCU to the bracket using the clip-on strap (1).
3. Connect the electrical connectors.
4. Connect the cell antenna coaxial cable (1) to the VCU (2).
5. Slide and secure the VCU bracket (1) to the metal brace on the instrument panel.
6. Install the upper trim pad. Refer to Instrument Panel Upper Trim Pad Replacement .
7. Install the windshield garnish molding. Refer to Windshield Pillar Garnish Molding Replacement .
8. Reconfigure the OnStar® system . Refer to OnStar Reconfiguration .

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