Program a 2003 cavalier remote key fob?

Answer 1

This is from GM's 1999 book. It should be the same.

Important! Once the BCM enters program mode, all transmitters must be programmed at the same time. Any transmitters not learned at this time will be erased.

1) Remove the key from the ignition cylinder

2) Remove the BCM PRGRM fuse from the fuse panel

3) Close all the doors

4) Close the liftgate

5) Turn the ign lock cylinder to the ACC. position

6) Turn the ignition lock cylinder to OFF, and then back to ACC within 1 second

7) Open and close any door
A chime will be heard when the system enters the BCM programming mode

IMPORTANT!
After 7 seconds a chime may be heard confirming successful synchronization. It is necessary to wait approximately 14 seconds for a second chime that will confirm successful programming.

8) Press and hold the transmitter LOCK and UNLOCK buttons simultaneously for 14 seconds

9) Repeat the previous step on each additional transmitter to be programmed.

10) Remove the ignition key from the ignition cylinder

11) Install the BCM PRGRM fuse back into the fuse panel.

Answer 2

Has to rely on GM dealer or locksmith, unless you can afford expensive Tech-II scanner costs thousands of bucks.