Try this procedure here and see if it works.If this is the procedure you have already followed let me know.
30-Minute Relearn Procedure
Use this procedure after replacing the following components:
- The passkey III (PK3) keys
- The theft deterrent control module
- The PCM, see important above
1. With a master passkey III key (Black), turn ON the ignition, with the engine OFF.
IMPORTANT: This procedure is not available on vehicles equipped with option code (Z49 or BAE).If replacing a theft deterrent control module with an GM SPO Replacement Part, perform the procedure to setup a new theft deterrent control module prior to the 30-minute relearn procedure.
2. Observe the Security telltale, after approximately 10 minutes the telltale will turn off.
3. Turn OFF the ignition, and wait 5 seconds.
4. Repeat steps 1-3 two more times for a total of 3 cycles or 30 minutes.
5. With a master passkey III key, start the vehicle. The vehicle has now learned the key transponder information and the PCM has now learned the fuel continue password.
IMPORTANT: The vehicle learns the key transponder information and/or passwords on the ignition switch transition from OFF to CRANK. You must turn the ignition OFF before attempting to start the vehicle.
6. With a scan tool, clear any DTCs.
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