Cadillac Repair: 1990 caddy deville,4.5, cadillac dealer, purple wire

Question
my car was broken into they broken my streeing column. so i went to the junk yard i found a streeing colunm with a key in it. so i bought it.. so i got it home  an started to put it in. i unhook the battery, then i unhook the air bag then i went to the wiring harness unhook it, an put the new one in.  hook up everything back up, turn the key an only thing i had was dash lights came on ,but wont do nothing esle wont start..so i put the old one back in it did the same thing ? so im i forgetting thing ? or did i lock anti-theftup on it. please e-mail me  

Answer
Check for battery voltage at the single, I believe PURPLE wire at the starter for battery voltage when you try and start the car.

Most likely the key that came with the used steering column is NOT programmed for the anti-theft module as the original key was.

You would need Cadillac dealer to reprogram.