Here's a breakdown of likely scenarios and how to troubleshoot them:
1. The car won't start at all, and you suspect the theft system:
* Check the key: The most common cause is a faulty key or key fob. Try all your keys. If you only have one key, it might be worn out or its transponder chip might have failed. A locksmith specializing in car keys can often reprogram or replace the chip.
* Battery Voltage: A low battery can sometimes trigger the theft system. Jump start the car from a good battery.
* VATS (Vehicle Anti-Theft System): The 1996 DeVille likely uses a VATS system. This system involves a resistor in the ignition key that the car reads. A faulty resistor in the key will prevent the car from starting. Again, a locksmith is your best resource.
* Passlock System (if equipped): Some 1996 models may have a Passlock system which is more sophisticated than the VATS system. Issues here are more complex and often require professional diagnostics.
2. The theft light is flashing (or staying on):
This usually indicates a problem with the system. You might need a scan tool that can read the codes from the car's computer to diagnose the specific issue. An auto parts store may be able to read the codes for free.
3. The car starts but then shuts off after a short time:
This could also be related to the theft system, but other issues (fuel pump, ignition switch, etc.) could also cause this. A diagnostic scan is highly recommended.
4. The alarm is going off randomly:
This can be caused by various factors, including a faulty sensor, low battery, or even a short circuit. Again, diagnosis is key.
What NOT to do:
* Don't try to bypass the system: Attempting to bypass the theft system is illegal and could damage your car's electronics.
In Summary:
You can't simply "reset" the theft system. You need to *diagnose the underlying problem*. This almost always requires a professional scan tool to read diagnostic trouble codes (DTCs). Take your car to a qualified mechanic or a locksmith specializing in car keys and immobilizers. They'll have the tools and expertise to properly identify and fix the issue. Providing the specific symptoms you are experiencing will greatly help them assist you.
