Important
Once entering this procedure, programming the first transmitter erases all previous transmitters. You must program all transmitters.
Program one vehicle at a time. One transmitter could be programmed into other vehicles that are also on program mode in close proximity.

Pull the MALL PGM Fuse.
Turn the ignition switch to the ACC position. The seat belt indicator flashes and the chime sounds 2, 3 or 4 times. This action identifies which type of BCM, is installed on the vehicle. Check that the BCM installed on the vehicle is compatible with all of the features on the vehicle. Keyless entry requires BCM type 3 or 4. Refer to Body Control Module Diagnostic Information in Body Control System for more information.
Turn the ignition switch from the ACC position to the OFF position, then back to the ACC position within 1 second. This action causes the BCM to enter the diagnostic/program mode. The BCM may flash and chime Diagnostic Trouble Codes (DTCs). The number of flashes and chimes equals the DTC number. If there are DTCs in memory, record the DTCs. Then refer to Body Control Module Diagnostic Information in Body Control System for more information.
Open and close any vehicle door. You should hear a chime if you are in the diagnostic/program mode. If unable to enter diagnostics, refer to Body Control Module Diagnostic Information in Body Control System for more information.
Press and hold the lock and unlock buttons at the same time on the keyless entry transmitter for 14 seconds.
At the 7-second mark, you may hear a chime. This chime feedback indicates that the transmitter has been resynchronized.
Continue holding the lock and unlock buttons until hearing another chime around the 14-second mark. This chime feedback indicates that the transmitter has been programmed successfully.
Repeat step 5 for the rest of the transmitters (for a total of 4 transmitter).
Exit the BCM diagnostics/programming mode:
Turning the ignition switch to the LOCK position.
Reinstall the MALL PGM Fuse.