Cadillac: 1990 Eldorado Ignition Cynlinder, lock cylinder, security light

Question
I replaced the ignition cylinder, now security light comes on and car will not crank. Control panel says wait 3 minutes. After it times out same thing. Checked resistant and the same. Any ideas.

Thanks

Answer
Does the ignition key tht you are using have the IDENTICAL resistance reading as the old key ?.

Did you plug in the 2 wire yellow connector under the dash that is attached to the ignition lock cylinder ?.

This is something that I heard about but do NOT know if it works or not as I have NOT tried it. With the ignition in the OFF position and the key in your pocket, Disconnect the battery and turn ON the headlights for 3 or 4 minutes and then turn the headlights OFF and reconnect the battery and see if the ke now works.

I have heard this from several people and I do NOT know if it works until I get a chance to try it.