Well, it looks like it happened to me, it is -5 degrees here and My car will turn over but not start. If I turn the key to "on" for 10 or 12 minutes and it starts. I have a 2000 Grand Am GT and I am not looking forward to spending the money to have this replaced.
I have read through this thread a couple of times and I wanted to summarize what I have learned to make sure I don’t screw up my car any worse. I'm not very good with this kind of stuff, but I have a brother that will do all the work for me.
Basically, the passlock system that is built into my car is meant to keep you from sticking a screwdriver into the ignition to start it. When you put in a key, two magnates send a current through the key and the computer measures the resistance. If the resistance is within the limit, the car starts, If not then it just turns over without starting.
To replace this system, it is alittle over 500 bucks (give or take a few). But there may be three ways to get around this. They were discovered because people were trying to hookup remote starters and the theft lock was killing the engine. The first is spray cleaner into the ignition to clean the magnets... Check… and no change… Use a different key and it works sometimes.
The second is if you can get the car running (e.g. the signal makes it to the computer) then cut the cable, the computer registers the broken circuit and goes into a failover mode. At that point the car will start no matter if the passlock system is working or not. The draw back is that the security light in the dash stays on and if the power goes out (e.g. the battery dies or need to be jumped) the computer resets and goes out of the failover mode. Some people put in switches so they can control this but you run the risk of the ignition being really broken and never getting it to start again which is necessary to get it into the failover mode.
The last idea is to measure what the set resistance is for your key and put in a comparable resistor instead of a switch. Basically, you bypass the ignition and the computer always thinks the correct key is being used. This way, if you the battery ever goes dead then you dont run the risk of not being able to start it again. Somebody had drawn a MS Paint diagram of this bypass but nobody really responded to it. Is it correct?
Anyway, If there is any information that is not correct or accurate, please let me know. I hope to start working on my car tonight (in the -5 degree weather.) and any frustration that I can avoid would be very much appreciated.