2001 Grand Prix GT Shifting hard occasionally

[nluchau]

Hello I'm new here.

I recently had my tranny fluid drained and a new filter put in prior to a trip to Montana. I noticed while in Montana that it started to shift hard. Once I shut it off and turned it back on it was ok. I noticed this off and on througout the trip.

I have read many forums and think it may be the pressure solenoid. Does this sound right? Everything is fine when you go to start it up, it acts up from stop and go traffic or whenever it gets warmed up.

Thanks for any insight on this matter.

Nick

[BNaylor]

Welcome to AF.

Best thing to do is get it scanned with a scan tool capable of reading extended GM codes. Typically, a P1811 DTC (Max Adapt, Long Shift) will show up confirming a problem with the PCS. This code does not trigger a SES/CEL light but will store for retrieval. The harsh shifting is because maximum line pressure is being commanded due to the DTC and shift adapts are disabled.

[nluchau]

Thanks for the welcome and reply bnaylor.

I do have an appointment next Thursday and they are going to put it on the machine. Maybe it's a coincidence but this started happening after the tranny fluid and filter was replaced and during a long trip.

I hope this doesn't end up very expensive to resolve. We have 86 thousand miles on it and prior to this haven't had a problem.

I'd appreciate any replies from people who have had this problem and what fixed it.

[nluchau]

ttt

[nluchau]

Anyone else heard of this before and what might have been the fix?

Thank you!

[jessep28]

I think I spent around $600 total, which isn't bad considering all they have to do when my PCS went wacky a year ago.

Good luck.

[nluchau]

Originally Posted by jessep28

I think I spent around $600 total, which isn't bad considering all they have to do when my PCS went wacky a year ago.

Good luck.

Thanks for the reply. It is indeed a PCS that is faulty and I got quoted just over 600 from the GM dealership and 570 from another place. This is crazy.

Now for my next question. Do I need to fix it now or can it wait a while? Will this cause any problems if I wait?

Thanks

[BNaylor]

The price quote is about right considering the amount of work that has to be done. The part itself is only around $50.00.

You don't want to wait too long because it may cause premature wear to internal components and the drivetrain. The hard shifts I had on my GTP were bone jarring. I went about 4 months with a flaky PCS solenoid until I was ready to do the work and had the time to replace it. I did all my DIY and it was a PITA.

In the interim try some LubeGard or Sea Foam tranny additive. It may help smooth some of the harsh shifting. Good luck.

[nluchau]

Thanks BNaylor!

I did put some Seafoams Transtune in it like a week ago. Still doing the same thing. I will have to round up some money some how and take it in.

I wonder if it will start acting up down the road again after I fix it.

How many miles you got on the new Solenoid?

[BNaylor]

The PCS was installed around 70K miles. To date I have 94K miles so it is hard to tell whether it will act up later on. So far so good, however, the possibility is there it could fail again. GM revised the PCS around the 2003 model year but the improved PCS is not retro-fittable to older 4T65E/HD autotransaxles.

[nluchau]

Originally Posted by bnaylor

GM revised the PCS around the 2003 model year but the improved PCS is not retro-fittable to older 4T65E/HD autotransaxles.

Does this mean the revised one will not work in my '01 Grand Prix GT?

[troy1]

Originally Posted by nluchau

Does this mean the revised one will not work in my '01 Grand Prix GT?

Yes, It won't work.

Originally Posted by bnaylor

The PCS was installed around 70K miles. To date I have 94K miles so it is hard to tell whether it will act up later on.

We had one go south with only 10K on it. GM needs to fire the engineer.

[je2345]

my 99' GP GT is doin the same thing! except mine shifts hard and tends to stall when idling! Only does these things when the engine has already warmed up. This is ALL after i got a tranny flush. AFter the flush all that started happening, and was then told that it was my TCC Solenoid that needed to be replaced. So I had my brothers boss who was supposedly a GM certifed mechanic for 25 years do it and it ended up messin my tranny up and i just got it rebuilt costing me $2200! Now its doin it again and the transmission shop is tellin me that its not the tranny and that its something to do with the electrical system!


If ne1 can help in identifying the problem before I have to spend a bunch more money please let me know! I have an appointment Monday, so gettin a response before hand will be great!!

[Squirlw/SE]

my '00 se, 3.1, automatic was doing the same shifting problem. i let the problem go because it was VERY random. then when i did do something to fix it, it cost me a tranny rebuild. if i was you, i'd get it fixed now or asap.

good luck,

T