Anti-theft system lights flashing

Let's not cut any wires on this one or we could be in trouble.

If the light is flashing that means there is an active theft issue. I would suggest starting with scanning for codes to see if the system will tell us what it sees as the issue.

If we don't have a scan tool do these steps in order.

Try to start the vehicle and then let the key fall back to the on position. The theft light should be flashing at this point.

Leave the key in the on position for about 10 minutes or until that light stops flashing.

Turn the ignition off.

Turn it back to the on position (don't try to start it) watch for the theft light to be solid, then turn off. Once it turns off try to start the vehicle.

If it is still flashing, we need to get codes.

Let me know if you have questions. Thanks

Cutting any wires would only serve to make things worse as it would effectively make the car a doorstop. There are a few common issues with GM anti-theft systems, however you need to determine what the issue is before trying to repair them or you just end up replacing good parts and chasing your tail. Follow the advice above and see what the car does. Also, where he references a scan tool, that isn't one of the free scans, they cannot access the security system, it takes a high end scan tool to do that.