OnStar Vehicle Interface Unit Replacement UE1

Important: The vehicle interface unit (VIU) 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 Front Trim Panel Replacement in Body Rear End.
2. Remove the mounting bracket fasteners (2).
3. Pull the mounting bracket (1) away from the body and place the mounting bracket  (1), module side-up, in the rear compartment.



4. Remove the VCU/VIU from the mounting bracket by releasing the module retaining tab (1). Pull the module up and out of the mounting bracket (1).



5. Remove the VIU/VCU modules (2) from the mounting bracket (1).
6. Disconnect the antenna and the electrical connections from the VCU/VIU assembly (2).



7. Slide the VCU/VIU assembly (2) out of the mounting bracket (1).



8. Remove the fasteners retaining the VCU mounting bracket (1) to the VIU (2).
9. Remove the mounting bracket (1) from the VIU (2).
10. The old VIU must be returned for core credit.

1. Install the VCU mounting bracket (1) to the VIU (2).

Notice: Refer to Fastener Notice in the Preface section.

2. Install the fasteners in order to secure the mounting bracket (1) to the VIU (2).

Tighten
Tighten the fasteners to 2 N·m (18 lb in).




3. Install the VCU (2) to the VIU and bracket assembly (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.

Important: Connect the electrical connector.

4. Apply than 0.2 N·m (2 lb in) of torque, or less, to the VIU thumb screw electrical connections.
5. Install the VIU /VCU assembly (2) to the mounting bracket (1).



6. 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 bay board.



7. Install the mounting bracket (1) to the vehicle body.
8. Install the mounting bracket fasteners (2).

Tighten
Tighten the fasteners (2) to 9 N·m (80 lb in).

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

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

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