CadILLAC deville wont start either ignition switch or key problem

SOURCE: unable to insert key into ignition switch

Try this pull the steering wheel as far to the left as possible and while it is in this position try to insert key. Sometimes the steering wheel lock will get in a bind and prevent the key from being inserted. Hope this helps!!!

SOURCE: 97 cadillac deville starting disabled car will not restart.

Like they say, "Cadillacs are easy to break into, but hard to steal!"

SOURCE: 2001 Cadillac Deville problems starting

I have had the same problem and I have come to the conclusion it is the security system. After 3 minutes the car will start so there is nothing wrong with the battery or starter. I have had it to the dealer a few times and they cannot solve it. It may be the locks on the doors and they may not be resetting properly. I have learned to live with it.

SOURCE: 2001 Cadillac Deville won't stay on after turning

EIther the IAC or throttle postion sensor is dirty or faulty. Or leaky vacuum hose somewhere. As long as it is not missing and running weird, then you may have bad coil packs.
You can go to autozone.com and register for free online repair manual for your vehicles if you need it.

Testimonial: "very helpful!!"

SOURCE: My 1990 Cadillac Deville wont start or engage starter

hey there. my name is dwayne, and im contacting you for help on my 98 caddy deville. well three days ago. i got a alarm installed. and friday i was driving on da high way and it just turned off. and smoke started coming from my steering wheel. engines coolant temp. was only 200 no smoke was coming from engine. now car wont start at all.!! please help