My '98 Bonneville won't start. I had to replace the ignition lock cylinder because it jammed up. Well, with the new one installed, the car turns on and all the accessories work, but there is no start; not even a click from the solenoid. I checked the battery and connections but they are fine. The headlight are bright. I suspect the security system. The guy who cut the new key was very careful to get the correct one, but I suppose anything is possible. Does anyone know how to diagnose this system?

Please tell us what your security light is doing when the ignition is on.

The security light is out.

Check your wiring on the ignition lock cylinder.

Check (compare) the resistances of the two key pellets, old and new.

The cylinder doesn't care what the resistance is, the module does. The module wasn't changed. Did you connect the tiny wires inside the sheathing?

Phil,
When you first turn the key to ON, the security light should light up for a few seconds. Are you getting that ? I just want to rule out a blown bulb.

Thanks for the help. It is late now so I will check tomorrow and post back what I find.

I went back and did some more diagnostics today. I didn't notice it before, but when the key is turned on, the stereo and fan come on, but the bulb check doesn't work and, of course, the car doesn't start. Based upon this, I assume that the fault is not with the "Pass Key" system but rather with the ignition switch. I can't think of anything else that would cause these symptoms.

Any suggestions would be appreciated, before I tear the steering column apart.

The bulb should come on as a bulb check as a minimum. You either have a burnt bulb, bad ground/voltage regulator, or a dead Vats module. Have you checked your fuses?

Yes, that makes sense, but it is not just the security light that is out. No lights come on. There is absolutely no response from the bulb check or start settings on the ignitions switch. That is why I think it must be the switch.

Ok, now I follow you. Definitely check your fuses and relays. Since your getting power out at other places I don't think its the ign switch at this point. I don't have a FSM here at work so I'm afraid we'll have to wait for someone else to list more specific items to check. Sorry.