Transmission shifting rough

My 2001 Grand Prix GT 3.8L 121,000km automatic transmission sometimes upshifts with a "jolt". It occurs at during town driving but not on a regular bases. When touble shooting, I shifted into Nutural and if felt as if it was down shifting.
The quick fix that I have been using is to simply turn off the ignition, wait for a few secounds, turn the ignition back on, wait a sec or two and of course re-start the car. I have had it serviced at 100,000 kms, the fluid was normal and clean. I have been checking the fluid on a regular bases and level and appearance is normal, so I don't expect any mechanical problems other than a sensor or shuttle valve.

Any Thoughts?

Welcome to AF.

When you had the service at 100,000km was it flushed or just a pan drop consisting of ATF and screen filter performed?

The hard/harsh shifting is most likely a pressure control solenoid (PCS) problem. High line pressure is being commanded on. Best thing to due is get it scanned and see if a P1811 DTC is stored.

The problem you are having is very common on 4T65E autotransaxles. Corrective action consists of replacing the PCS.

Actually come to think of it, all they did was a flush. What kind of work/cost am I looking at to replace the PCS? Am I looking at any futher damage to the tranny if I let it go too long?

That wasn't good. Flushing is not recommended and afterwards you get these wierd tranny problems causing solenoids to stick or act up. Most of us stick to the basic pan drop service.

Cost varies depending where you live. In my area transmission shops charge around $550 USD just to do a PCS job. Hard to say whether it will damage anything. I know of GP owners that ran up to a year with a flaky PCS solenoid. Turning the engine off helped and sometimes the problem would not show up for awhile. Very intermittent. But it is best to get this issued resolved early. And don't let the tranny shop or GM dealer talk you into a rebuild. It is not necessary at your mileage. Good luck.

http://www.atraonline.com/source/amembers/directorysearch.cfm?searchtype=reb

http://www.atraonline.com/

The first link is a search page, the second is the organization's homepage. The Automatic Transmission Rebuilders Association is a trade group with bylaws, ethics rules and standards for its member shops to follow.

I would search for one in your area as a start. I am real big on certifications when dealing with anyone, but that is my opinion.

The problem started before the flush, but the "generic" garage that I took it to, didn't have a clue to what I was talking about. The GM garage thought it may be the PCS, but I wanted to research it before they play the guessing game with me. Now I'll just have to get a quote on the repair.

Thanks for the info.

I am having the exact same problem with my car... it only seems to do it after a while. I turn off the ignition and turn it back on in a couple mins and its fine. My car has 134,000 km on it and I got a tranny fluid/filter change done about a month ago. Im praying its not something major thats gonna cost me a fortune, cause my other car died last week :(

When I get an estimate from the GM garage, I'll pass it along to you. We can compare to see if there is any differences in price between provinces.

When I get an estimate from the GM garage, I'll pass it along to you. We can compare to see if there is any differences in price between provinces.

Sounds good, Im gonna go in the morning to have the codes pulled to see what comes up then Ill go from there. I dont go to GM though because they charge WAY too much for everything. My mechanic gives me 20% discounts on parts when I deal with him.

The GM dealership was useless.

Another garage suggested a filter and flush before doing the 800$ work

A third that specialises in tranny work knew exactly what the problem was when I described it. 400$ He has seen alot of these PCS problems and informed me on what exactly was going on. Yes the PCS is "gummed" up or faulty, the engines's computer sences the late shift, due to the lack of press, "codes" it and then delivers more pressure for your next shift, hence the uneven shift. Shutting the inigition off resets the code, thearby the problem for a time seems to have gone away. :screwy:

So now I have that to look forward to have fixed, as well the oil pan will soon need to be replaced as well, which is also going to cost, as I have to lift the engine to give the pan clearence.

Good thing the rest of the car is running great.

i am having the same shifting problem and this is the place to find your answers. i took my car to be scanned, as per AF, and they found the P1811 code. the recommendation was a tranny rebuild. the PCS is buried in the tranny and if you are going to replace it, you may as well rebuild. the PCS, as i was told, causes "longer shifting" periods and therefore the hard shifts are a result. i love the GP SE i have so it's getting fixed.
thanks to all of the AF that helped me diagnose the problem with the tranny as well as my fan switch "ignition switch".

Squirl

Hate to bump a 2 month old topic, but...

Is this a common problem for 2001 SE's also? I can't quite find what kind of transaxle those use.

Hate to bump a 2 month old topic, but...

Is this a common problem for 2001 SE's also? I can't quite find what kind of transaxle those use.

Your model Grand Prix uses the same autotransaxle. The 4T65E. GM RPO code M15. Check the SPID label on the back of the trunk lid and look for M15.

Ok, I'm going to ask this question, because it sounds like the SAME thing that is happening with the 95 Grand Prix I bought my son last week. Is this possible? And $400 would be a ROUGH estimate of the repair to a PCS? Because that would "Hurt" a lot less than $800 or more for a whole new transmission.