After installing a new pcm, some vehicles may require a security procedure before the vehicle will allow the engine to start.  The steps below outline the proper procedure for a number of GM vehicles.

Late model Grand Am, Alero, Malibu, and other N-body Vehicles

1. Set E-brake - This will keep the head-lights from coming on, and draining the battery during the procedure
2. Roll down driver’s window - This is necessary because otherwise you will have to sit in the car the whole time because you cannot open the doors or trunk during the procedure.
3. Reach through driver’s window, attempt to start vehicle.
4. When vehicle does not start, simply let go of the key, and it will fall back into the RUN position.
5. Walk away for 11 minutes.
6. Come back, turn the key OFF for 10 seconds
7. Turn key to RUN position
8. Once the car stops dinging (about 5 seconds), start vehicle.

Late model Grand Prix, Monte Carlo, Impala, other W-body Vehicles

1. Set E-brake - This will keep the head-lights from coming on, and draining the battery during the procedure
2. Roll down driver’s window - This is necessary because otherwise you will have to sit in the car the whole time because you cannot open the doors or trunk during the procedure.
3. Reach through driver’s window, attempt to start vehicle.
4. When vehicle does not start, simply let go of the key, and it will fall back into the RUN position.
5. Walk away for 11 minutes.
6. Come back, turn the key OFF for 10 seconds
7. Turn key to RUN position
8. Wait for car to stop dinging (about 5 seconds)
9. Attempt to start vehicle
10. When vehicle does not start, simply let go of the key, and it will fall back into the RUN position.
11. Walk away for 11 minutes.
12. Come back, turn the key OFF for 10 seconds
13. Turn key to RUN position
14. Wait for car to stop dinging (about 5 seconds)
15. Attempt to start vehicle
16. When vehicle does not start, simply let go of the key, and it will fall back into the RUN position.
17. Walk away for 11 minutes.
18. Come back, turn the key OFF for 10 seconds
19. Turn key to RUN position
20. Wait for car to stop dinging (about 5 seconds)
21. Start vehicle