Cadillac Repair: 93 Seville with NO KEY RESPONSE, chevy caprice, cadillac dealer

Question
Hi.  My son was given this car from his grandparents a week ago.  He drove it for 2 days and suddenly, it would no longer start.  The SECURITY light would not go off so we towed it to the local Cadillac dealer for repair.  He said it was the ignition switch, it had burned out.  Today he called and just told me that was not it and it still has NO KEY RESPONSE.  He has no idea what's wrong (THE CADY DEALER) and he is sending it to an electrical specialist.  I was wondering, my daughter used to have a chevy caprice and it had the same symptoms, it turned out to be a bad sensor after 3 trips to the dealer at $700 each...   ANY IDEAS???

Answer
I do these every week or so. The problem is they do NOT know what they are doing.

You will need simple Electrical schematics, Test procedures and picture locations of the components within the system that is causing you problems of which can't be done on this website which only allows one picture. I do not have a website so you will have to e-mail: onlineautohelp@msn.com in order to obtain the information.