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Pontiac Grand Prix Transmission Problems



  • bruntzjpbruntzjp Posts: 1
    I noticed recently that my tranny makes a rattle sound when I punch it on the highway. I have a 2002 GT with about 53k on it. When I drop the hammer it seems like it has less power than it used to and it will rev very high while it slow climbs in speed. Once it starts to rev high, 4-6 rpm, i can hear a rattle from underneath me. I just had the 50k eng service done a few months ago. Had the belt replaced, coolant flush, and tranny flush. A car buff buddy said it may be because I got the tranny fluid flushed. Said something about the seals and leakage or something. Could this be it? I don't want to have the tranny replaced. I've been staying safe and driving slow keeping it at 2-3 rpm, but we all know that's no fun. I've never seen so many people get pissed off on the highway in one week! Someone please help me!!! I hate this slow driving!!
  • Hi acinder,

    I have a 1999 GT. Mine already had the "latest update" per GM too, but when the mechanic called technical service in Detroit they gave my car a new update that had not been released yet. This was in February of this year. I began the whole ordeal of taking it to the garage 12 times in September 2006 through February 2007.

    Someone else on this message board had asked for the program/calibration number too, but when I asked the service manager, he said he didn't have one because they did it over the phone.

    Here is what I can get off my my FINAL work order/receipt. I don't know if it will help.

    "Drivability Concern"
    "Check shudder under load"
    "Reprogrammed to the latest update per technical assistance."

    Cost $44

    The dealership I went to is actually a Chevrolet (not Pontiac, but still GM of course) dealership in southern Ohio. I don't know where you live, or if that would be a benefit. The service manager who had been there for years recently took another job, so I'm not sure if the new one would be able to help you.

    I understand the nightmare that you are going through all too well. I have actually been through it twice. I started having this problem when the car was three years old. They replaced parts then and they replaced parts again this time for lots of $$$ before we finally found the problem.
  • acinderacinder Posts: 3
    I am beginning to think that GM is keeping the update a secrete because they dont want to get sued. Just think of all the owners who were told their transmissions needed to be rebuilt and it was actually a faulty program. I am going to have the dealer call gm and say they rebuilt the trans once and now they are having the problem again. I figure the cars that have gone through the rebuild already are the only ones they are releasing the update to.
  • swg1swg1 Posts: 1
    GT0102 or anyone, please help! I am having the exact problem on my '99 GT, the Tach will randomly shut off, causing a surge, and the TRAC OFF light comes on simultaneously. Sometimes when this happens, it also kills the engine, just did it yesterday going 60 mph. My brother in law is a mechanic and has tried everything, but nothing is working, does anyone know what the source of the problem is?? HELP! :sick:
  • ksenaksena Posts: 1
    hey maby some one can help me out with this problym ive ben haveing on my 1997 grand prix gtp. At first my transmishion was acting up on me shifting very hard and sliping once and a while, aslo my speedomiter drops down to zero when i give it a little gass and the transmishion ingages. i tried replaceing my speed control sencor and it fixed tha problym with the hard shifting but my speedomiter still only works while my car is coasting and not when im giveing it any power.

    The only mods. that i have done to the car are a short ram intake, throttle body spacers, smaller pullys and a transmishion intercooler.

    Any help with my situation would b greatly apprecieated.
  • apple5apple5 Posts: 1
    My 00 GP GT did the same thing, My brother is a parts manager at our local GM place and I let him take it to work one day and he put the computer on it and it come back with a Tranny Code not sure what the code was, but the code had something to do with a pressure sensor under the side cover on the driver side of the transmission. The service Engine light never came on, but he cleared the code out anyway, and it didn't do it for almost a month, and one day on my way to work I stopped at a red light and when i took of BOOM hard shifting started again, every time i stop it and take off it shifts hard from 1st to 2nd.. I wasn't really worried about it, until I started to notice when It shifted hard from 1st to 2nd I could hear this high pitch WINE inside the tranny, So i took it back to the GM place, and we hooked the Tech 2(Tech2 is a computer that most GM places have that can tell you near about everything the car is doing)>> up to my car and drove it around town as we monitored the transmission with the tech 2 when it was shifting hard the tech 2 was showing the transmission pump was putting out to much pressure causing the pump to wine, So with the previous code that was on the computer a month ago that was showing up a pressure sensor error, pressure to high or low, and know seeing that the tech 2 was showing to much pressure I had the pressure sensor changed, and it fixed the problem.. The the problem first started the car had 85k miles on it, It know has 143k on it and transmission works great......
  • acinder, let me know how it turned out.

    I was signed up for e-mail updates when someone else posted on this forum, but it hasn't been e-mailing me.
  • coblurcoblur Posts: 4
    Wow Apple 5, you really hit it on the head! I read your post and took my car out for a long drive. Sure enough it started to shift hard and I noticed for the first time a high pitched whine!! Almost sounds like a power steering pump. I'm going to get the pressure sensor changed. I will let you know!! This is great!
  • '89 Grand Prix with slipping trany,
    changed fluid and filter w/2 bottles of Lucas additive
    result - no reverse (smells burnt) shifts really slow when in drive. Is there any hope and if not is there a quick fix solution to get another week out of her??? Please help!
    It's a 4 speed automatic on a 2.8L motor
  • I have a 2001 Grand Prix GT that has been giving me lots of problems lately. I think that they may be related. First was water getting into the blower motor, so I had to replace the blower and hopefully stopped the water leak with some caulking.

    Then the power locks stopped working when you put the car in gear and when you shut the car off, they work OK if you push the lock or unlock your self.

    I have been having problems getting the key out of the ignition sometimes too, this seems to come and go but I found a trick on the web to use a straw to unlock the key release.

    Now the latest problem is that sometimes the car won't go into park. It will go through all of the gears but when you get to Reverse it won't go past that into Park.

    Could the locks, key sticking and not going into Park all be caused by the same problem, and if so what could it be? I have a feeling that they are all related some how!
  • Hi, I tried to reverse my 99 Grand Prix GT out of the driveway this morning and the shifter seems to be stuck. When I apply my brake in order to engage the shifter from "park" to "reverse" the shifter seems to be stuck. I am parked on a slightly sloped driveway. The car starts fine however I can't seem to get it into any gear? Any suggestions would be greatly appreciated.
  • cnwcnw Posts: 105
    Sounds like you might be experiencing "torque lock". When parking on a slope, if the car rolls forward or backward in "park" after you take your foot off the brake, it applies tremendous pressure against the parking pawl--a pin that locks the transmission so it won't turn. Subsequently, when you attempt to take it out of "park", there is a great amount of side pressure against the pawl pin, thus making it hard to shift. Simple solution: Apply the emergency brake/parking brake BEFORE shifting into "Park". :)
  • i have a 2005 grand prix which i love but it seems to hesitate whenever i accelerate its happening more and more lately,any idea's
  • A few things that come to mind 1. check the spark plugs. 2. check the air and or fuel filter. 3. Bad gas (dirty gas) try filling up with "premium gas" throw some gas line cleaner in with the fill up.

    Try these things and let me know. Good Luck!!!
  • I was driving my Grandprix when it downshifted to passing gear I lost all gears but first. I got it back to my house then it set for a week. I had to move it when I got in it I had all gears back but reverse. When it gets warm I loose 2,3,and 4th again. what could cause this. I had no warning before I lost the gears
  • Watch that my car does not have reverse at all I put it in and the engine just revs and until the tranny gets warm I have all the other gears. once it is warm I loose all but 1st
  • I have a 2004 Grand Prix GT2. It has about 68,000 miles on it. Sometimes when I go from reverse to drive, then step on the gas, it hesitates. It doesn't do it all the time. I don't notice any other issues. Do I have a possble problem? I have an extened warranty to 72,000 miles, so if there is a serious problem, I can get it repaired.

  • Hey,

    I got a 2001 GRAND PRIX, aprox.150,000. the other day driving on the highway my car downshifted as i was passing a car as usual, but then never shifted back. i am currently stuck driving in 4th gear. could this be related to the software issue?
  • Hello,
    Im not sure if this is a PCM program issue or a pressure sensor issue? It hard shifts from 1 to 2 and sometimes 2 to 3. This only happens when the car is warmed up. I dont hear any wine like APPLE5 said.
    Thanks for any help
  • Hi, Apple 5 and all other pontiac guys

    I've been trying to find the part (Pressure sensor)[see post 90] for my car. The dealer thinks I'm nuts and doesn't know what part I'm talking about. Do you know the exact name, or a number for the part?

    I'm still shifting hard and whining away!
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