Oldsmobile/Buick Repair: Gm ignition quesion, sophisticated security system, mumbo jumbo

Question
I have a 1991 Cadillac De Ville that won't crank from the ignition key. The old cylinder had a broken wire so I bought a new cylinder with a new key that matched the old one (#2). Supposedly this cylinder matches the old one but  some mechanics tell me that the key has to be programmed and some tell me that all they have to do is match the old one which was #2. I replaced it and it still won't crank. The security light still comes on when the key is turned. They tell me that as long as that light is on that the car will never start. My question to you is -How do I disable this security mumbo-jumbo and make the car crank and start from the key? Or figure out what the problem is?

Answer
hi mike, well there is no bypassing this dude,caddilac has a very sophisticated security system.but you have to have the coded key or this system won,t work.there is way too many anti theft devices on this car to keep you from doing just this now i am not saying not possible .i just don,t know of anyway and i have tried.you could make it crank from the inside but the injection system still would not work .they don,.t make an intake for a reg fuel system so there is no way of changeing that.not many options here.well hope this helps some please vote for me ty billymac