how do I start my 1996 Cadillac DeVille if the ignition has been altered to do so
You need an original VATS (Vehicle Anti Theft System) key. There were 15 different keys available for your car. Each has a visible "chip" on the key shank. This is a resistor block that is matched to the vehicle. If no keys are available you'll have to find out which of the 15 possibilities your car needs. Then have a VATS key blank cut to fit the ignition lock cylinder. HTH. -Jim
Search Cadillac DeVille Questions
Are you a UK consumer? CarGurus now has a discussion forum in the UK.
Cadillac DeVille Experts