Security system

Which process?

Turn the key to on position, wait 10 minutes, turn to off position wait 5 seconds. Repeat three times and it should start.

Is the light flashing with key on?

Yes, it doesn't stop flashing

Ok, turn key to run,light should be flashing,let sit for 20 minutes or until light goes solid ( no flashing ) . then try to start.

Ok I'll try that. Thanks

This is a very common problem on GM vehicles. The security system is known to fail. If the system cannot get the correct signal from the key, it assumes the key is incorrect and goes into SECURITY lockout mode. (prevents hotwiring) This has been happening with GM's for a very long time. There are ways to bypass this now. Read through this page for info, solutions as well. http://www.diy-gm-security.com/