How to reset theft system

There's no reset. You have the VATS security system. The most common problem is the ignition lock cylinder. You have a visible chip on the ignition key which contacts two tiny wires inside the lock cylinder when you insert the ignition key. These wires break off and no longer make contact with the chip on the key. When this happens the security system shuts down the engine. The new lock will come with a template for cutting new VATS keys. There were 15 possible VATS key blanks. To determine which blank you have measure the resistance value of the chip on the old ignition key. Compare that to the chart below to determine which key blank you need to be able to start the engine. Use the template that came with the new lock for cutting the new VATS keys. No further reprogramming is required. Hope that helps! Jim

Try disconnecting both battery terminals then hold them together for a min or so. This will reset everything . then just reconnect