For 1990-2009 cars

Important: Between 2-4 transmitters can be programmed to a vehicle's theft deterrent system. A minimum of 2 keys is required to perform the procedure. You must obtain all the keys from the vehicle owner before programming any of the following items:

• | Any keys

• | The engine control module (ECM)

• | The intelligent switching unit (ISU)

• | The theft deterrent control module

Important: Do not connect the scan tool to the data link connector (DLC) before the key is placed in the ignition. If the scan tool is connected before the ignition is turned ON, then communication errors and the programming procedure may not complete.

Any vehicles keys not programmed during the programming procedure will be inoperative after the programming sequence is completed.

### Conditions

Use the procedure after replacing the following items:

• | Any keys

• | The engine control module (ECM)

• | The intelligent switching unit (ISU)

• | The theft deterrent control module

### Immobilizer Programming Procedure

1. Acquire the 6-digit security code from the tag provided with the keys at delivery. If you are unable to locate the tag, a General Motors dealership can obtain the 6-digit security code through the Part Locator System.
2. Turn ON the ignition, with the engine OFF.
3. Install a scan tool.
4. Select IMMOBILIZER PROGRAMMING FUNCTION from the BODY menu.
5. Follow the scan tool instructions with each key until all of the keys are programmed.
6. Use the following to enter the 6-digit security code to proceed:

• | The up arrow to enter numbers

• | The down arrow to enter letters

• | The left/right arrows to move to the next space

7. Continue following the on-screen instructions with each key until all of the keys are programmed.
8. Cycle the ignition 3 times as indicated by the scan tool.
9. Turn the ignition to the LOCK position.
10. Disconnect the scan tool.
11. Test the operation of all keys.

Important: If any key does not operate properly, make note of that key.

12. If any key does not operate properly, perform this procedure once with all keys.
13. If the same inoperative key does not start the vehicle after repeating the immobilizer programming procedure, replace that key.
14. If 2 or more keys do not function after repeating the immobilizer programming procedure, then refer to Theft Deterrent System Inoperative .
15. If the vehicle is equipped with RKE, perform the Transmitter Synchronization procedure. Refer to Transmitter Synchronization .