Your problem is probably your theft deterrent system. This is a very common problem on chevy cars (and others for that matter). Here are some solutions I gave someone else on this site with the same problem:
* Go to a dealer and get charged a ridiculous amount of money for a diagnosis and a fix that may or may not work.
* Try the GM reset procedure for passlock:
" Turn ON the ignition, with the engine OFF.
" Attempt to start the engine, then release the key to ON; the vehicle will not start.
" Observe the security telltale; after approximately 10 minutes the telltale will turn OFF.
" Turn OFF the ignition, and wait 5 seconds.
" Repeat steps 1 through 4 two more times for a total of 3 cycles/30 minutes (the car may start after only one time though); 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.
Important: 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.
* Bypass the system (check online for infos)
* Attempt to fix it your self, in which case you'll have to determine what's wrong: passlock sensor, ignition cylinder, BCM, bad connection, etc
Wednesday, September 16th, 2009 AT 4:08 PM