GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2001 🢒 Seville - RHD 🢒 Body and Accessories 🢒 Cellular Communication 🢒 OnStar Vehicle Communication Unit Replacement

Removal Procedure

    Object Number: 625727 Size: SH

    Important: The vehicle communication unit (VCU) has a specific set of unique numbers that tie the module to each vehicle. These numbers, the 10-digit station identification and the 11-digit electronic serial number, are used by the National Cellular Network and OnStar® to identify the specific vehicle. Because these numbers are tied to the vehicle identification number of the vehicle, you must never exchange these parts with those of another vehicle.

  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. Object Number: 649490 Size: SH
  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.

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

    2. Object Number: 649490 Size: SH
  2. Slide the VCU (2) into the mounting bracket (1).

    3. 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.

    4. 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. Object Number: 702924 Size: SH
  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.

    7. Notice: Refer to Fastener Notice in the Preface section.


    Object Number: 625727 Size: SH
  7. Install the electrical component mounting bracket nuts (2).

    8. 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. Important: After replacing the VCU, you must reconfigure the OnStar® system. Failure to reconfigure the system will result in an additional customer visit for repair.

  9. Reconfigure the OnStar® system. Refer to OnStar Reconfiguration .