questionscan anyone diagnose my pontiac?

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Just a guess but the key has a chip in it (I think). Try a different key. Hope it is just the chip in the key.

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@caffeine_dude: I'd second that. Could also be the antenna coil if it does it with all the keys. As always it's hard to say without looking at the car, and most of my experience is on the parts sales side. Sometimes it could be a bad PCM but it doesn't really sound like it's that bad.

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could also be interference from say, a cell phone or some other RF generator.

j5 j5
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@caffeine_dude: I switched from my regular key to my spare key. Did not help.

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@cowboydann: What's a PCM?

@j5: I generally don't have my cell phone while driving, believe it or not.

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@hot72chev: Powertrain Control Module, other manufacturers might refer to it as an ECU (Electronic Control Unit)

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Did you try changing the headlight fluid? Could also be a failed headlight fluid pump.

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@figgers3036: No, but I changed the air in my tires and checked the kanooder valve - that didn't help either!

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@hot72chev: Hm. Yeah that valve causes lots of problems - Have too high of a Vernortiner level and you'll blow off your transmission, have too low of a Vernortiner level and you're liable to have the hood fly up and block your vision while driving on the highway. Definitely double check that Kanooder valve.

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It's almost certainly the antenna coil (preventing it from receiving the signal from your key) or the ECM just being buggy. It's hard to imagine it being anything other than one of those two things.

You say it's stymied your mechanic, but have you taken it to a dealer? Unlike a mechanic, they could throw an ECM in there and see if it's fixed and then put your old one back if that isn't the problem. ECMs are expensive enough that a regular mechanic won't have one just sitting around to test whereas the dealers will have a parts bin full of 'em. Same goes for the antenna coil.

(Oops. Just re-read the post and see that you mentioned it stumped a dealership. Personally, I'd go to another dealership or else demand that the first one take it more seriously. You paid them many thousands of dollars for a product that is causing you to be stranded. They have to be able to fix it. They have the right to charge you for it, but they can't just shrug and send you on your way.)

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I remember the old GM Passkey system was simply a tiny magnet built into the key and a tiny magnetic switch built into the ignition switch.
This system was easy to get all out of whack. With as simple as the system was, it surely must be easy to manipulate it.
I can't remember when GM started embedding chips into the key. The old magnetic system had a little black square on the side of the key with a little metal "minus" in the middle.

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I would like to thank everyone for your input. You have given me some great ideas. I think I will check into another dealership and definately ask about the antenna coil.

This had been a minor headache compared to other mechanical and electrical problems which can come up on all cars. My car is 9 years old and paid off, so I can put up with it for now.

@figgers3036: thanks for the smiles!

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@hot72chev: You're welcome! Though my evil goal in life is to, someday, somehow, convince someone that there is such a thing as headlight fluid and that they need to replace it often.

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I'm not sure if the dealership would be able to do this, but being an ODBII system with a significant number of options to modify within the tune (think computer programming, not changing spark plugs), there should be a flag to simply disable the PATS (passive anti theft system).
I haven't had to tune a GM car, so I'm not sure how to disable yours off the top of my head or what tuning software would be required.

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Same thing happened on my Firebird. The security system not getting the correct "signal" from the key and the security system kicks in and locks you out for 10 or 15 minutes. I had to eventually replace the ignition lock and get new keys.

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One other free thing to try is to ensure the car is in park or neutral.

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@kornkid42: I have heard this problem is common on GM products...do you recall how much that new ignition lock set you back?

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@kornkid42: Your diagnosis seems to be the closest yet. Thanks!

Monday was the straw that broke the camels back, when my Pontiac failed to start twice in one hour.

I went to another dealer yesterday. 3-1/2 hours and $500 later, I have a new ignition cylinder and new keys. They assure me this will solve the problem. We shall see.

I won't believe it until it goes 6 months with no security light coming on.