Transmission shifts roughly

Friend of mine just bought a 2001 grand prix gt (automatic)...all in all he got a good car, but immediately after buying it, the transmission began to shift hard. nothing, that makes noise while it does it, but you do feel a slight jerk as it shifts from year to year. I;m no mechanic, but in my limited auto knowledge, this isn't good. It's driveable, but I want to make sure it's not a sign of things to come with the transmission. Is there anything I can check, or maybe change the trans fluid and hope it goes away. He bought it from a dealership with a warranty, so worst come to worst he can take it back, but he really like grand prix so he doesn't want it to go that far. It only has 88K on it, and has never been in an accident or had any major problems with the car.

Welcome to AF.

In most cases hard or rough shifting is caused by a flaky pressure control solenoid (PCS) which is a common problem with the 4T65E transmission. When scanned with a trans capable scanner a DTC error code of P1811 may be stored. GM has a TSB out on this problem.

Tell him to take the car back to the dealer and complain about it because repairs could be expensive.

Hey Bob, is this one of those issues that some have fixed by unhooking the battery negative cable overnight? The PCS is a known problem as well, and I agree that if the car was bought at a dealer, to take it back to them and complain.

Hey Bob, is this one of those issues that some have fixed by unhooking the battery negative cable overnight? The PCS is a known problem as well, and I agree that if the car was bought at a dealer, to take it back to them and complain.

Not to my knowledge Rich. Only TCC issues to date such as fishbite and chuggle. I've disconnected the battery overnight on PCS problems and it doesn't do anything to help the problem. As a matter of fact I've installed a replacement PCM and no help. It is a tranny valve body issue.

Great, I couldn't remember for sure, thanks for the clarification. BTW, welcome to AF RacerM, I didn't notice this was your first post.

Thanx everyone, I didn't realize this was my first post either, lol...I've gone to the Bonneville forum several times I thought I posted in there already.

He took it back to the dealer, the dealer told it was nothing and that's how it shifts. He's gonna take it to his Uncle who is a mechanic to see if it's anything major.

I'll mention what you guys said to him as well.

unfortunately the valve it self wears make a grove and sticks. So no PCM reset will work. Well I shouldn't say that if for some strange reason the TAPS gets reset it will smooth out for a day or two.


Troy

Thanx everyone, I didn't realize this was my first post either, lol...I've gone to the Bonneville forum several times I thought I posted in there already.

He took it back to the dealer, the dealer told it was nothing and that's how it shifts. He's gonna take it to his Uncle who is a mechanic to see if it's anything major.

I'll mention what you guys said to him as well.





well i dont know about you guys but my car shifts pretty darn smooth and its got 95k on it. i would definetly be concerned if the transmission on a grand prix was shifintg hard my guess is that it dosent have a shift kit in it. so i would fight it. ive had 2 prixs now and they both shifted like a dream