I am sorry that you have not been helped yet. I just came online and saw your question
You dont mention having done the relearn procedure, so this is where to start, the security relearn procedure. The battery needs to be in good condition for this
30minute GM relearn procedure:
1-TurnON the ignition,with the engine OFF.
2-Attemptto start the engine,then release the key to ON (vehicle will not start).
3-Observe the SECURITY telltale(this is the security light), after approximately 10minutes the telltale will turn OFF.
4-Turn OFF the ignition, and wait 5 seconds .
5-Repeat steps 1through 4 two more times for a total of 3 cycles/30 minutes(the vehicle is now ready to relearn the Passlock(TM) Sensor Data Code and/or passwords on the next ignition switch transition from OFF to CRANK). IMPORTANT: The vehicle learns the Passlock(TM)Sensor Data Code and/or password ***** the next ignition switch transition from OFF to CRANK. You must turn the ignition OFF before attempting to start the vehicle.
6-Start the engine(the vehicle has now learned the Passlock(TM) Sensor Data Code and/or password).
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