Hello my wifes uncle has a 99 bonneville. It died on him the other day while driving down the road. he brought it to a shop and they replaced the key switch, starter,battery,and had the Gm dealer make a new key for it.. Still no start!! well he finally gave up and towed it to my house and asked me to figure it out.....arrgghh electrical problems. well when i run a jumper to the starter with the key on it will fire right up and run fine. so i think the security system is ok. Ichecked with the voltmeter and followed the wire from the starter solenoid up to where it enters the cabin on the passenger side. no voltage at all when key is turned ,,up to there. Anybody know where at on the inside parts or anywhere else i should check next and what readings i might be looking for? I;m really hoping i dont have to dissassemble the dash for a part that is easily accesible that i didnt know to check lol. thanks Johndh2

When you try to start it, can you hear the starter cranking?

no clicking. I hooked up the volt meter to the solenoid wire and no voltage at all when the key is turned.

Well i did some more digging and i removed the ignition switch from the steering column. when i dissasembled it the contacts for the start portion appear to have melted a little and pushed down into the plastic housing.... possibly causing an open when the key is turned to start. I ordered a new one which wont be in untill tuesday, I will post an update on the situation then.. thanks John!

PROBLEM SOLVED! thanks for the help! i put the new ignition switch in yesterday and it now works like a charm. now for those who might have this problem in the future... the switch i am referring to is not the key switch. it is on top of the steering column and the key moves a rod that engages this switch. Every parts store i called tried to sell me the key switch and i had to explain what i wanted to them.. lol