1. Insert the key into the ignition and turn it to the "On" position (Do not start the engine).
2. Press and hold the "Unlock" button on your key fob for about 10 seconds.
3. While still holding the "Unlock" button, turn the key to the "Start" position.
4. The theft deterrent system should be bypassed, and the engine should start.
Note: This method may not work on all 1996 Cadillac models, and it's recommended to consult your vehicle's owner's manual or a professional mechanic for specific instructions on bypassing the theft deterrent system.