It's in anti-theft mode. GM systems are very effective at keeping owners out of their cars. If you have tilt wheel and move it a lot, the wires in the steering column could be broken. Often these systems will let the engine start if you wait an hour or use a different key. If that doesn't work, you can try this relearn procedure that some of the other experts use:
30 Minute Re-Learn Procedure
1. Turn ON the ignition, with the engine OFF.
2. Attempt to start the engine, then release the key to ON (vehicle will not start).
3. Observe the SECURITY telltale, after approximately 10 minutes the telltale will turn OFF.
4. Turn OFF the ignition, and wait 5 seconds.
5. Repeat steps 1 through 4 two more times for a total of 3 cycles/30 minutes ( the vehicle is now ready to relearn the Passlock Sensor Data Code and/or passwords on the next ignition switch transition from OFF to CRANK).
The vehicle learns the Passlock Sensor Data Code and/or password on 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 Sensor Data Code and/or password).
Friday, August 12th, 2011 AT 5:35 AM