2000 GMC Sonoma 6 cyl Four Wheel Drive Automatic 65000 miles
2000 gmc truck alarm went off. After starting and running the truck then turning it off. We tried starting it a few minutes later and ignition switch was loose would not start. Security light is flashing. We disconnected the battery to try to reset. Did not work. Lights come on when key is turned but key will not engage the starter.
You probably have a bad ignition lock here but I'm giving you the relearn procedure to try it anyway.
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(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 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(TM) Sensor Data Code and/or password).
7. With a scan tool, clear any DTCs if desired (history DTCs will self clear after 100 ignition cycles).