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2000 pontiac grand prix 3.8 non-supercharged engine cranks and dies, after several attempts it runs great and never skips or stalls. I have installed new crankshaft sensor. The computer had codes P1628 and P1629 which there is a GM service bulletin on..."theft deterrent module has chaffed wire in steering column which should be repaired and theft deterrent module replaced". GM technician checked this and NO chaffed wire in steering column, in fact car does the exact same thing with theft deterrent module unplugged and also if you rmove the passket II fuse, it still does the same thing. I should mention that the service engine light was on and the technician's code reader read, "cannot communicate with car's PCM. After I removed the battery cable for an hour the service engine light (bad gas cap) light went off and the code reader was able to communicate with the PCM and found the 2 codes above. The gas cap was replaced, the service engine light has come back on once and also the "Traction Control OFF light has come on and off intermittently". I am trying to saty away from the GM service department because they replace parts and never take any part off if it doesn't cure the problem. I'm getting a new PCM "to try" also need to know if the new PCM MUST be programmed before it will work, some say yes, other's say no???? The car started this about 2 months ago, and the only other problem I've noticed is that it the engine turns over 6-8 times before starting instead of usual 1 0r 2 times. Fuel Pump was replace with new GM pump about 4 months ago because the fuel sending unit on it was bad(car was running fine both before and after replacing pump). I'm thinking maybe a PCM going bad simply because the code reader would not communicate with the PCM at one point?? and why would the car run with theft deterrent module unplugged and /or passkey III fuse removed. Puzzling to me!!

Edited by Customer (name blocked for privacy) on September 13 2005 at 12:35 PM

Customer (name blocked for privacy)

Status: Closed Value: $20

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1g2wj52k9yf280145is there any way to check the pcm other than trying a new one? my brother owns a parts store and has said i could try a new pcm, but one mechanic tells me i need to have the new pcm programmed and another tells me all i have to do is plug it in, what would you suggest...also how would one check the voltage problem at the pcm, i have a 12 volt voltmeter. I stated the codes wrong, one is P1626(NOT P1628) and teh other is P1629.. both which I already had researched and found the fuel cut off -anti theft fuel enable ckt and thefet deterrent fuel enable/incorrect/no signal

Edited by Customer (name blocked for privacy) on September 13 2005 at 1:50 PM

1G2WJ52K9YF280145 Is there any way to check the PCM, also how do you check the PCM voltage problem, I have a 12 volt voltmeter. My brother owns parts store and has said I could "try" a new PCM..but one mechanic says the new PCM must be programmed and another says it does not?? I misquoted one of the codes, it is P1626(not P1628) both these codes I had already researched and found anti theft fuel enable ckt and theft fuel enable incorrect/no signal. would just plugging in the new PCM and trying it harm anything??

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There are no warranty claims against that car.It's a fleet car from Illinois.The new pcm would need programmed.Firsthogman asked me to check this for you.The replacement of the pcm would also require a theft deterrent relearn procedure.Plugging in a new pcm won't hurt anything but it won't start unless the above procedures have been done.

Hi; I have a copy of the theft deterrent relearn procedure: 1.insert the master black key into ignition switch 2. Turn to "on" position without starting engine. the security light should illuminate and stay on 3. wait approx 10 minutes or until security ligh turns off 4. repeat steps 2 through 4 two more times with the same key 5. turn the ignition key off. the vehicle will now learn the key transponder information on the next start cycle 7. start the vehicle, if vehicle runs normally, and security light is off, the relearn is complete. 8. if additionsl keys are to be relearned, turn the vehicle off, insert the key to be learned and turn ignition switch on position within 10 seconds of removing the previously used key.

This is copied and pasted from a pm from the original person asking the question. thanks for the answer about installing a new pcm and reprogramming, can the new pcm be programmed right out of the box before it is installed in the car by using VIN number? also, is there any way that the old pcm would NEED reprogramming, the only parts replaced recently was a fuel pump and a different guage cluster was tried to check and see if the gas guage was bad, it was the sending unit on the pump that was bad. but, it was doing this before the pump or cluster was even touched. the gm service bulletin 02-08-56-002 describes the 2 codes found in the computer and the recommended repair,(repair a chaffed wire from theft deterrent module in the steering column wiring and also replace the theft deterrment module) a local GM technician went completely through the wires from the theft deterrent module in the steering column and said there was DEFINITELY NO chaffed wires. The only reason I am concerned about the PCM is that the mechanic's code reader at one point gave a reading of cannot communicate with pcm, after disconnecting battery cable for an hour or so, it read the 2 codes. also, the service engine light has come on a couple times and the traction off light also has come on and went off several times, each time leaving NO codes in the computer! I can install the computer, I have always tinkered with cars since I was a kid, even worked in a Pontiac dealership at one point before going to USPS. No offense, but the wrong dealership can cost you a lot of money on a problem such as this...I personally know this, I've seen parts replaced until the correct bad part was found and NO parts taken back off, our dealership is a small town dealer and I'm afraid that the theft deterrent module will be replaced, quoted approx $300 with labor, passkey III module replaced quoted approx $300 with labor, and PCM replaced and programmed, quoted approx $350-400 with labor. I hope you don't take offense, I feel you would be well qualified to test some of these before replacing everything that could be wrong, i'm not that convinced with my local small dealer. i can't understand why it would have the exact same symptoms 1. turns over 6-7 times before cranking instead of 2-3 times. 2. sometimes cranks and does not die, other times must crank it 7 or more times before it continues to run. 3. after it cranks, it runs great, never has died once it starts and keeps running and what makes me want to look at the PCM is why would it have all these same symptoms with the theft deterrent module unplugged and the passkey III fuse removed...these 2 things were tried separately, not at the same time. I certainly believe the fuel sensor relay is cutting off fuel to the injectors(maybe I should check the voltage on the fuel sensor relay??) does it sound like a PCM defect to you??? if so, I can buy a PCM at NAPA from my brother for under $100, and I would like to know if the PCM must be plugged in and installed in the car to be programmed or can it be programmed right out of the box using VIN? thanks and help!! Bobby I'm really not a cheapskate, I am a 100% combat disabled vietnam vet(9th Infantry 68-69) on a fixed income and can't afford to throw $1,000 bucks at this car.

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Thanks guys, I have checked the ground wires and it is still doing the same...I am taking it to the dealer in the morning...i hope they can diagnose without and before replacing modules, sensors or PCM, at least that is going to be my request of them, Bobby I will post what they find.

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The Dealer service department checked the voltage to the PassKey III Module behind the small rubber pulloff cover beneath the ignition key and found it wasn't getting the required 5 volts from the PCM. He then unplugged the PCM connectors and replugged them in....even though they were NOT loose, at that point he rechecked the voltage at the PassKeyIIIModule and then it was reading the proper 5 volts. He rechecked the volts there at the Module a couple days and they never changed, I have driven the car considerably since and it has never stalled after cranking and it even cranks normally without spinning the engine 6-10 times. I have my fingers crossed that this was the problem, works fine so far!

I would have changed the terminal in the pcm connector for the 5 volt signal but some times when you cycle a connection like was done it seats a terminal that wasn't properly seated.I think you will be ok now.

Master ASE Certified.L1 Advanced Engine Performance Certified.Pa Emission Repair Technician.Just Answer Car Category Mentor.

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