Transmission issues - 2001 PA

I'm having a couple of issues with my transmission and want to avoid some hefty repair bills.

1. A couple of times, I have shifted into reverse (cold engine/trans) and either have the car move slowly when trying to back up or hardly at all. A couple of seconds later, it's fine. When warm, it's fine.

2. There are a couple of hills that I will downshift rather than brake to control my speed. Afterward, when moving the shifter from 2-3 and from 3-OD, the car will take a second and then slam into the next gear (eng/trans warm).

3. Occassionally, the car will upshift a little harsher than normal (during normal operation, no manual down/upshifting) (eng/trans warm).

4. Occasionally, when driving (eng/trans warm)(seems to be about 45 mph or so), the car will shudder as if the transmission is slipping. It seems to do it always when I am cresting a very slight hill near my house. Today, I was driving up a slight hill about 45 mph and it shuddered very noticably. It happened several other times today, but less noticably.

Now, about 9 months ago, just before my ext warranty ran out, I had my car checked out by my mechanic (due to the harsh shifting) and he said everything seems fine, that the transmission could use servicing, but no burnt smell or unusual color. So I took the car to the Buick dealer to complain about the harsh shifting, and if anything was malfunctioning, it could have been repaired under warranty. They said they had to service the transmission first, then they could check it out. I had them service the transmission...they opened it up, no burnt fluid, no metal shavings...just needed to be serviced. After that, they kept the car for an extra day and could not replicate the issue. They told me I was being "too sensitive" to the transmission shifts...that it shifts fine.

I have done some research and found TSB 00-07-30-002B "A/T 4T65E - Harsh shifts/shudders/slips/DTC set. I haven't seen any warning lights come on, nor have I had the car checked for DTC's yet. The TSB indicates that the Pressure Control Solenoid may need replacing.

I'm just not sure if the issues that my car has fits within the TSB's description. Others who have had this issue on the Automotive Forums (for their Buick Century/Chevrolet Venture/Olds Intrigue/Pontiac Bonneville) seem to indicate that they are having symptoms that are a lot more severe than mine, especially with the harsh shifting.

My questions are:

1. Does my car's more subdued symptoms seem to indicate a PC Solenoid replacment, as the TSB indicates?

2. I've read that the PC Solenoid can be replaced w/o any removal of the transmission (at least on other types of cars). Can the Park Avenue's PCS be replaced w/o R&R? (Looking to save $ on labor costs)


Thanks in advance for your help in this.

The symptoms for a bad PCS solenoid will vary but your symptoms sounds consistent with a flaky PCS solenoid. Get it scanned with a trans capable scanner or one that can read GM extended DTCs and see if a P1811 (max adapt, long shift) is stored which does not trigger the SES/CEL light. I recall the GM TSB addresses this specific DTC. Also, a bad PCS will affect TCC functions.

Since you are unfamiliar with the exact location of the PCS solenoid or replacement of it see the thread below posted at Buick Tips & Maintenance.

http://www.automotiveforums.com/vbulletin/showthread.php?p=4994238#post4994238

As you can see the PCS is located under the side cover assembly (driver's side) at the valve body. Not exactly a DIY job but it can be done DIY with the right tools and equipment to include lots of patience.

The engine and autotransaxle are dropped intact on the subframe assembly and then tilted which will facilitate removal of the side cover assembly. However, many other parts have to be disconnected or removed before that like the hubs and axle shafts, motor mounts, etc.

Thanks. My mechanic has the scanner that should pull the DTC's. I'll take it to him to scan.

Have no fear. I won't be trying to replace this by myself. I'm IQ-deficient when it comes to working on engines :lol: . My dad made me learn, but the engines were much simpler on the cars we had. I'll have my mechanic do the work. I think it was on the Olds Intrigue forum where an owner had this sort of trouble and needed to get his PCS replaced and others were saying that he should tell the mechanic/shop that he did NOT want the transmission R/R and that he only wanted the PCS replaced...in an effort to save labor costs involved in the R/R of the whole transmission. I just wanted to be sure that it was possible to replace the PCS in the Park Avenue w/o having to remove the transmission.

Thanks again.

BNaylor, will this issue always prompt a trouble code? I took the car in to the mechanic today to have it scanned. The car acted up half the trip there, but no DTC's were found. The mechanic used 2 different scanners to do it, one was Mastertech and one was a new one (Tech II ?). Neither scanner came up with any stored nor any pending DTC's.

I have an appt set up for Friday to get the PCS fixed, but if not having a trouble code may point to a different cause to my car's problems, then I can cancel my appt and have the car checked out further.

Good question but I know of a few instances where the PCS solenoid was bad but did not generate any DTCs. But in one case it was confirmed out of spec by doing a line pressure test. Otherwise you are just taking an educated guess based on the specific symptoms. There is a fitting at the top of the autotransaxle where this can be done. The specs are available in documentation like the 4T65E ATSG Service Manual in which hopefully your mechanic has.

I've talked with my mechanic and we are still on for Friday, but we've set up a line pressure test to take place before they start work on the PCS solenoid. It's another hour of labor, but if the solenoid is good, I'll save $500+ on an unnecessary repair right there.

So I have 2 more questions...:uhoh:

1. Assuming that the PCS solenoid is bad/flaky...but with the problem being intermittent, how likely is it that the line pressure test will confirm that the PCS solenoid is the problem?

2. If the test shows the solenoid to be good, what would be your next guess as to the cause of the problems?

OK, a third question...I've just been told it could be a "valve body and oil pump" instead of the PCS solenoid... your thoughts?

I appreciate your help in this.

One other thing, in addition to the above questions...is there any other test I should look at having done before I proceed with any repairs?

If the problem seems to be more persistant when trans is warm,,,,,shift accumulators may have broken cushion springs,,,other issue would be seals on accumulator pistons worn,,,,by replacing seals on pistons and buffing the bores with "scotch-brite",,,will get it back on track.......also fill this trans to "full" + one quart,,,has a very shallow pan,,,under certain conditions transmission will starve for oil,,,,,will not hurt trans ,,,it will thank you!!!!

Are there any tests that could help my mechanic narrow down the problem? I dropped the car off tonight for them to start working on in the morning. I can call and leave a message to have them call me before they start with some instructions. Thanks for your help on this. I appreciate it.

Well, it was all one big false alarm. My transmission is fine...the mechanic found that my coil packs are malfunctioning, sending sparks all over the place and causing misfires.

A $950 day at the spa for the car (new coil packs, wires, full tuneup and a full-on transmission service/flush) and I'm promised a better than new car with glowing skin and a renewed sense of self. We'll see if the car's as happy as the mechanic's promising. :grinyes:

Thanks for your help guys! Very much appreciated. :cheers: