2000 Century Harsh Shifting when warm

Problem is intermittant. All OK when cold. After a few miles of warm up the transmission starts making a buzzing noise which increases in pitch with engine speed then all gears shift harshly. Its been getting worse lately. It was rebuilt a year ago due to a failed torrington bearing. Several gears and other stuff was replaced, metal pieces found in the pan. Took it to the tranny shop that did the rebuild. They saw a trouble code P1811 which they can't be sure is the cause of the problem. I've tried to determine what this code means but it's not listed in any documentation I found. They want to tear it down again and that will cost me a bunch. I hate to let them do that when they are unsure of what the intermittant problem really is. I'm afraid they'll fix everything but the problem. Anybody seen this problem in a 2000 Century or other 2000 FWD GM car?

If someone could assist in the definition of the code, I can assist w/ troubleshooting. W/ respect to the noise, two things come to mind. The first, and most likely, is a plugged trans filter. The restriction may be causing the pump to cavitate, affecting directly the shift quality due to low pressures. This situation could also cause the 1811 code if it relates to a vague powertrain code. Vague codes include such things as random misfire. If the trans intermittently slips, vague codes such as random slippage may be set. The other possibility is the pump or pressure regulator valve may be intermittently affecting fluid pressures, causing the same problems. Ray

Thanks for the offer Ray. I forgot one piece of info, I just had the fluid/filter changed in that tranny shop that did the rebuild a year ago. That was the first (and cheapest) thing to try. One thing which agrees with what you said is that shop manager also thought it may be that the pump or regulator is Flakey when warm. I hate to shell out about $1000 minimum for a R&R and teardown when the problem is so undefined. I'd also have to rent a car for 2-3 days. I'll keep looking for the definition of the P1811 code. One other thing that comes to mind was that a Bearing disintegrated causing the first rebuild. Do you think some fragment could still be circulating somewhere through the passages causing this? If so, then why do I have the problem only when its warmed up?
-- Paul

Some things to remember is that the fluid viscosity drops as temperature rises. This in itself will change fluid pressures. The other thing to remember is that internal clearances will change with the same temperature rise. It is quite possible for the Torrington's demise to have left debris in the transmission. Question: Is the noise constant w/rpm or does it change with shifting? Is the noise different when the trans is in third than when in reverse or overdrive? Something else to consider is the possibility that the valve body is not seating correctly with the housing, causing internal leaks, and pressure loss. Maybe this shop would check the bolts on the valve body as a goodwill gesture? More food for thought. Ray

:smokin: i've seen loose valve body's on all make's :smokin:

I have a 2000 Century and it does the same thing. It started at about 70k miles. It will run for a while and then start whining and shifting hard. If I turn off the motor and start again, it will quit ... at least for a while. It appears to happen sooner on hot days and in heavy traffic. The only thing I've done to the transmission is change the fluid at about 60k when I purchased the car.

To answwer Ray's question the Noise (whine, or buzz) increases with engine RPM. Its the same in any gear or neutral. But as Lanierboy describes, it runs for a while fine, then all the symptoms start up. Yes I can shut it off and it ceases for a little while, then comes back. Just lately, and just before the symptoms are solid, it seems to jerk between gears when starting out in 1st, when the whine and hard shifting appears this behavior goes away.
I think I got a definition on the P1811 trouble code
DTC P1811 Maximum Adapt and Long Shift
This code does not turn on the SES Light
This comes from the web site http://pcm.dxsoftware.com/dtcs.htm
Which looks like a good resourfce for these.
Anybody got an idea what this means?

If this code definition is correctly defined, it marns that the shift for which the code is set is too long for the clock in the computer. Essentially, it means that during the time the computer is preprogrammed to delay timing advance, the sensors on the input shaft of the trans and the output shaft should reflect the ratio of the gearset and the output shaft. That means that, if the trans is supposed to upshift from second to drive, the ratio between the output shaft and the input shaft should be essentially the same, if the torque convertor is engaged. The computer knows the torque convertor status since it established it. If, during a normal shift, which should take about a 1/2 to one second, the time frame established by the software, is exceeded, the code is set. This code essentially indicates either slippage in the trans or a slow upshift. Both are indicative of fluid pressure problems, or problems with the clutches controlling the planetary. Ray

Interesting definition. When the car is having the problem, the shifts between all gears is very quick and abrupt - not like slipping. But I do feel a shudder on the 1-2 shift when I don't have the problem (cold) under fairly heavy acceleration. Now I'm really confused. Maybe the code is saved from some time long ago.

If the shudder is confusing the PCM by allowing an extended shift, or slippage, the result may appear to be an extended shift. It might be wise to have the code cleared and then evaluate the trans' operation. If the SES light is not illuminating , the code is not a fresh one. The code is only fresh if the light intermittently illuminates, and that is the only code set. Ray

GM has a bullentin on this condition the repair is to replace the PCS solenoid inside the trans.

Slips, Harsh Upshift or Garage Shifts, Launch Shudders, Flares, Erratic Shifts and Intermittent Concerns, DTC P1811 or P0748 Set (Replace Pressure Control Solenoid Valve Assembly) #00-07-30-002B - (07/19/2002)

Here is what a shift adapt is!!
Adapt Function
The 4T65-E transmission uses a line pressure control system, that has the ability to adapt line pressure to compensate for normal wear of the following parts:

The clutch fiber plates
The springs and seals
The apply bands
The PCM maintains information for the following transmission adaptive systems:

Upshift Adapts (1-2, 2-3 and 3-4)
The PCM monitors the automatic transmission input shaft speed (AT ISS) sensor and the vehicle speed sensor (VSS) in order to determine when an upshift has started and completed. The PCM measures the time for the upshift. If the upshift time is longer than a calibrated value, then the PCM will adjust the current to the pressure control (PC) solenoid valve to increase the line pressure for the next shift in the same torque range. If the upshift time is shorter than the calibrated value, then the PCM will decrease the line pressure for the next shift in the same torque range.

Steady State Adapts
The PCM monitors the AT ISS sensor and the VSS after an upshift in order to determine the amount of clutch slippage. If excessive slippage is detected, then the PCM will adjust the current to the PC solenoid valve in order to increase the line pressure to maintain the proper gear ratio for the commanded gear.

The TAP information is divided into 13 units, called cells. The cells are numbered 4 through 16. Each cell represents a given torque range. TAP cell 4 is the lowest adaptable torque range and TAP cell 16 is the highest adaptable torque range. It is normal for TAP cell values to display zero or negative numbers. This indicates that the PCM has adjusted line pressure at or below the calibrated base pressure.

Clearing Transmission Adaptive Pressure (TAP)
Updating TAP information is a learning function of the PCM designed to maintain acceptable shift times. It is not recommended that TAP information be reset unless one of the following repairs has been made:

Transmission overhaul or replacement
Repair or replacement of an apply or release component (clutch, band, piston, servo)
Repair or replacement of a component or assembly which directly affects line pressure
Resetting the TAP values using a scan tool will erase all learned values in all cells. As a result, the PCM will need to relearn TAP values. Transmission performance may be affected as new TAPs are learned. The PCM must also relearn TAP values when the PCM or the transmission is replaced.


Bascily what this says is the PCM is a learning PCm it learns the drivers habits and learns the wear of the trans over time and uses this info to change the shift points to be less noticable.

After any trans repairs the shift adapts have to be cleared and relearned.

Here is alittle info about your code of P1811!

Circuit Description
The transmission pressure is modified by an adaptive modifier which controls the shift execution time. This test checks the time required to accomplish the shift. If the shift takes longer than 0.65 seconds and the adaptive modifier cannot shorten this time, then a counter increases by one.

If the PCM detects a counter value of 2 during one trip, then DTC P1811 sets. DTC P1811 is a type C DTC.

Conditions for Running the DTC
The shift is adaptable.
The 1-2, the 2-3 or the 3-4 shift adapt cell has reached its limit.
Conditions for Setting the DTC
The 1-2, 2-3 or 3-4 shift is longer than 0.65 seconds, twice in one trip.

Action Taken When the DTC Sets
The PCM does not illuminate the malfunction indicator lamp (MIL).
The PCM commands maximum line pressure.
The PCM freezes shift adapts.
The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Failure Records.
The PCM stores DTC P1811 in PCM history.
Conditions for Clearing the DTC
A scan tool can clear the DTC.
The PCM clears the DTC from PCM history if the vehicle completes 40 consecutive warm-up cycles without a non-emission-related diagnostic fault occurring.
The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM.
Diagnostic Aids
Ask the customer about possible overloading, exceeding the trailer towing limit, or towing in overdrive.
Ensure that the PCM has the latest calibration update.

Wow! thats a lot of good information, Flatrater . I suppose replacing the PCS solenoid is not something I can do in my own garage. I think I understand a little more now. I'm going to provide this to my Tranny guy so he'll understand. Thanks.

No the PCS is no an easy job it requries you to remove the trans side cover and then you need a scanner to clear shift adapts. Clearing the TAPS is the most important part of the job.

GM has a problem with the PCS solenoids they are made of a softer metal than the hole they ride in after a while they wear and start hanging up.

Flatrater, thanks for the great information. This is something I'll attempt in the near future.

To clear the taps. Will a regular ODBII scan tool work or do I need something special.

I am sure some of the scanners will clear TAPS but not all of them.

Hello all,

I came to this forum to post a question and found a thread already dealing with my problem. I have a 2000 Century with a little under 50k miles, with high line pressure causing harsh shifts, whine, etc when the car is warm. My problem is that I've already had the PCS solenoid replaced, and the symptoms remain.

About a month ago I subscribed to Alldatadiy.com and found the TSB regarding the P1811 I was seeing, and took it to a shop asking for a new PCS valve assembly. They found that the entire transmission was heat damaged due to some pulling I did during a move last summer with too big a trailer. (I simply didn't have the money to rent a truck + car dolly.) Clutch material was starting to flake off, I had damaged a bearing (they didn't say which one), and the PCS solenoid was heat damaged. They rebuilt the transmission and replaced the solenoid, adding an external radiator-mounted transmission fluid cooler. They said that they reset the PCM, which I assume cleared the TAPS.

I got the car back a couple weeks ago, and found that the symptoms remained. However, it now takes a little longer, normally about 40-50 miles of driving from a cold start, to obtain the symptoms. Sometimes P1811 is set, sometimes it is not. Thanks to Flatrater, at least I now understand the reason for that. Clearing the DTCs, even when there are no mode $03 or mode $07 codes set, seems to be a temporary fix, but the symptoms return after a few more miles of driving. The shop says that they inspected and tested all transmission and drivetrain components during the rebuild, so that the problem must be caused by a faulty PCM or other electrical malfunction. They say that my particular PCM is not programmable, and want to try switching out the PCM. I think that there are more options left to explore first.

Question #1: Is it possible to replace the PCS solenoid without replacing the related valve assembly or another related part which may be clogged or heat damaged, thereby alleviating but not eliminating the problem? I need to be armed with more specific knowledge regarding the PCS valve assembly before I start asking the shop questions that may seem insulting to their workmanship or make me appear ignorant.

Question #2: Does anyone have info about the Mode and PIDs of the GM enhanced powertrain data for this car? I recently bought an Elmscan and would love to be able to program my laptop to watch real time GM enhanced OBD2 data, including shift times.

On a possibly related note, I'm experiencing an occasional starting problem. I will detail that in another post.

Thanks in advance for any help.

Phil

Wow this forum is great. I have a similar problem with my 01 regal with 3.8 non supercharged at about 60k miles.

It just started. This car has lots of pep and I drive it pretty hard.

If I’m driving along at about 50 mph and step on it to pass, it downshifts, engine revs but no acceleration and it doesn’t up shift. If I let off the gas it upshifts but I have baby it in high gear to accelerate.

If I drive easy it will work fine in the city, and upshift on the highway and go into over drive, but I can’t kick it and go any more. It just downshifts, screams, but doesn’t go.

I Changed the tranny oil and filter about 3 months ago.

Does this sound like the same issue? Do they have to remove the tranny to replace this sensor? Any idea of cost?

I could post the whole bullentin from GM for you but GM does moitor this board and I could get into legal trouble over it but I can say that most complaints concerning transmissions is covered under this repair.


dude99x
Since 1996 all GM cars and trucks have a re-programable PCM it is a federal law. They are lieing if they say otherwise.

Nick 2.0 It sounds like your problem is that it's slipping when it downshifts, not the harsh shift caused by the PCS misbehaving. I've had automatic trannys slip before and the only cure I know of is a rebuild. :(

:banghead: This is becoming a real issue with all cars with the 4T65E transmission. The epc valve works so hard to adapt every shift it wears the valve body. Gil Younger (TransGo) shift kits fix this. Installing the kit will require R&R of the valve body, and on most cars this will require transmission R&R. This is not a DIY'er job. It is also recommended to RDI the transmission. We almost always find additional wear inside. Common wear points are the very small splines on the end of the 4th gear clutch hub. Also the drive chains stretch a great deal. The bearing that the input sprocket rides on had a high number of failures on earlier models, so replacing that is a good idea too. These really are a great transmission and usually they come in nice cars, so don't be afraid to pay for the repair. Fix it and keep smiling. :biggrin:

Well regardless of what Transdoc says about how good the 4T65E is, it sounds like a lot of us are having troubles with them. Mine failed the first time at 51K miles with a bad bearing which took out a lot of other stuff costing me over $1200 and now this shifting problem. I know the 4T65E is pretty sophisticated compared to transmissions of the past, but I'm used to cars lasting 200K miles before major repairs. Can't they make them sophisticated AND reliable?
But thanks to everyone who has contributed to this forum I've ;earned quite a lot about this problem and I will print out a copy for my friendly Transmission repair professional just so he has the same information.

I have similar problems with my 2000 century with 63k miles on it sometimes while driving on the streets for longer period of time it starts to shift hard but it feels like only on 1st and 2nd gear once it get to about 40mph it goes smooth, on the highway no problems at all, I have never changed my transmssion oil or filter.

***Reposted under Buick > Regal Forum http://www.automotiveforums.com/vbulletin/showthread.php?p=2232313 ***

I've got a 99 Buick regal gs, that I just replaced the tranny in, from reading I see that it looks like I need to have the shifting patterns reset.

I'm having a problem that I think is different from what is in this forum, but you guys seem to know alot about this tranny.

First of all what is the easiest way to determine which tranny I have.

Second, my symptoms are that erratically (more bad than good) the tranny will not shift down at a stop. When I pull the manual shift lever back it will only go into 2nd, and when I move it up it will only go into 3rd. no first, no OD.

I have read that there are several sensors, and things that could be going bad. I took it to the tranny shop and the guy thought that it was prolly the computer. Me I don't think thats the case. I have access to several interchangeable computers, but they have to be programmed before they work. Is it possible to DIY change speed sensors or check modulator line?

Thanks for any info.

ps the new tranny reportedly has 47k miles on it. (the original tranny was stolen before I bought the car)

looking at the reciept from the tranny shop I had 8 codes from while I was repairing it (it would be nice to know what codes I'm getting now)
1860,713, 717,748,753,758,1602,1810
He said that the reason it was shifting weird was because it was getting low voltage. He thought that it was because the computer was bad, but I really don't think that's what it is.

I have been having the same problem with my 98' Bonneville. It only does it after you drive it at least 15 miles, depending on traffic conditions. It shifts real quick and hard into all gears, but, you can shut the car off and restart it and it won't do it for another 10-15 miles. It is at the Pontiac dealer now as we speak having a recall on the fuel pressure regulator repaired and they also checked the transmission. They told me it was the Valve Body Solenoid and the plate assembly. The cost: $705 for the solenoid and $234 for the plate assembly. A total of $939 parts and labor and $65.73 GA sales tax, that's $1004.73!!
I called around and it cost about the same at other repair shops and they said they would rebuild the transmission for $1800 to $2200 depending on what all had to be done. I'm not sure what to do, the car has 130k miles on it and I would hate to spend $1000 and have to spend another $2000 down the road to have the whole thing rebuilt. Hope this helps....
G.W.

Wow, I didn't see this particular thread. My car has the exact same problems as everyone else here. I'm taking it to a mechanic tomorrow. I have the specific same problem as someone else -- I've already had the PC Solenoid Valve replaced and the problems persist. I already started a thread of my own. If anyone has suggestions, they would be appreciated. From what I've read there are problems with the powertrain control module, TAPS (?), DTCs (?) and other parts maybe relating to the torque converter? What do some of these things stand for?

Well this is the deal,,I had the same problem and brought the car in to the dealer, mine is a 2001 Century with 80k miles got the same code after a $65 charge and they said that if you didnt do the scheduled maintaince trans.flush at 50 k miles there is a chance you have a pluged pressure control valve from the dirt.Yea you got it,,its in the transmission,,any way ,not happily I had them fix it @ approx $1000.00 .I complaned to GM and am waiting for there reply .In my eyes this is eather a way for them to sell Extended Warrente,or a engerining defect and should have a recall.Good Luck and be ready because if you dont fix it it will trash the trans.:2cents:
To answwer Ray's question the Noise (whine, or buzz) increases with engine RPM. Its the same in any gear or neutral. But as Lanierboy describes, it runs for a while fine, then all the symptoms start up. Yes I can shut it off and it ceases for a little while, then comes back. Just lately, and just before the symptoms are solid, it seems to jerk between gears when starting out in 1st, when the whine and hard shifting appears this behavior goes away.
I think I got a definition on the P1811 trouble code
DTC P1811 Maximum Adapt and Long Shift
This code does not turn on the SES Light
This comes from the web site http://pcm.dxsoftware.com/dtcs.htm
Which looks like a good resourfce for these.
Anybody got an idea what this means?

I just bought a 2001 Buick Century a few months ago. I have been having the same problem with my car shifting while warm. It usually happens when the car has been idling (say waiting at a bank for 5-10 min). As soon as you take off, it has a hard shift to the gears and makes a grinding noise. When the car is cold or when it's going at a constant speed on the road, then it doesn't shift hard. I've already changed the transmission filter/fluid with an additive. They are now wanting to change the selenoid since that's the code that is coming up with the diagnostic test. Changing the selenoid will be $600.00. Does anyone know why my car is doing this? Please help! Amy

Well this is the deal,,I had the same problem and brought the car in to the dealer, mine is a 2001 Century with 80k miles got the same code after a $65 charge and they said that if you didnt do the scheduled maintaince trans.flush at 50 k miles there is a chance you have a pluged pressure control valve from the dirt.Yea you got it,,its in the transmission,,any way ,not happily I had them fix it @ approx $1000.00 .I complaned to GM and am waiting for there reply .In my eyes this is eather a way for them to sell Extended Warrente,or a engerining defect and should have a recall.Good Luck and be ready because if you dont fix it it will trash the trans.:2cents:

Yeah, I was told the same thing about making sure the trans gets flushed on schedule, but I think that's bull. My car started having the problem at about 52,000 miles. After I had the work done, the mechanic mentioned that for GM transmissions you should really have them flushed w/ filter change every thirty thousand miles. Even my 1995 Intrepid with the supposedly bad Uldradrive transmission didn't need flushes that often, and it lasted up to 177,000 miles.

As for the guy with the 2001 Century, good luck. As you've probably read, there are those of us who have had this problem, had it "fixed" only to have recurring transmission problems. I can't afford to keep throwing money at this car, and right now I think it's at the point where they'd have to take my transmission apart to determine what's wrong, and if the warranty I bought doesn't cover the work, then I'm screwed. So right now I'm living with the transmission problem and once this car dies I'll hopefully be ready to move up to a Japanese car.

Yeah, I was told the same thing about making sure the trans gets flushed on schedule, but I think that's bull. My car started having the problem at about 52,000 miles. After I had the work done, the mechanic mentioned that for GM transmissions you should really have them flushed w/ filter change every thirty thousand miles. Even my 1995 Intrepid with the supposedly bad Uldradrive transmission didn't need flushes that often, and it lasted up to 177,000 miles.

As for the guy with the 2001 Century, good luck. As you've probably read, there are those of us who have had this problem, had it "fixed" only to have recurring transmission problems. I can't afford to keep throwing money at this car, and right now I think it's at the point where they'd have to take my transmission apart to determine what's wrong, and if the warranty I bought doesn't cover the work, then I'm screwed. So right now I'm living with the transmission problem and once this car dies I'll hopefully be ready to move up to a Japanese car.

Well I was fixing to dump some :2cents: into the transmission of this car. I've already paid $82.00 for new transmission fluid, filter, and additive. Of course this didn't clear up my problem. Now they are telling me the selenoid. I'm glad that I found this forum because now I know there are people experiencing the same problem that I have with my car. I've been explaining my strange car problem to people I work with and family. Everybody seems to think it's very weird. They say if it's the transmission, then why does it not act up all the time? My car was acting fine for the last week until today when I was waiting 10 min. at the bank with the car idling. All of a sudden, I heard the grinding noise. It just changed to normal to the noise and while it did this, the temperature gauge starting increasing over the half line. I knew what was next--the hard shifting after take off. After the car is in drive mode and has time to cool off some, then it's back to normal again. It's driving me crazy! Something I have noticed that seems to work some is putting fuel injector/carberator cleaner in the gas tank. It doesn't seem to do it as bad. After reading this forum, I'm thinking that I would be stupid to dump money into fixing the selenoid and rebuilding the transmission when it's not working for some of the others. I wouldn't doubt if this was just some simple thing like a stinking computer code going haywire. I hate to say this, but I do think the next car I buy will be foreign made like a Toyota Camry.

You can read about my 01 Buick Century getting a new tranny at 23K miles (sic) on this site (different forum):
http://www.automotiveforums.com/vbulletin/showthread.php?p=2970196#post2970196

Here's a summary for yall:

Some 4T65E transmissions have a design/manufacturing defect where the TCC valve wears its sleeve (one metal is harder than the other) which causes it to leak. This valve is called the 'apply' valve because it applies the gear. Because it is leaking, it is applying incorrect pressure to the clutches and they wear. As they are wearing fast, the adaptive system is working extra hard compensating for this, causing it to wear and also strain the rest of the system. Eventually, there is damage to significant components and bearings. There are two solutions, neither cheap:

1) Go to dealer and get a remanufactured tranny. Expect to pay $3500 + tax (checked in NJ 04/2005).
Dealers do not (the half dozen I called, big and small) do not rebuild trannies - can anyone vouch for this "categorically"?

2) Go to chain (AAMCO, etc.) and get an R&R. Expect to pay about $1000 less - they will also tow for free if you do the repair with them (AAMCO). You have the option of JUST doing the R&R (which means they take it out and put it back after looking at the damage) for around $500 + tax + towing. If you do repair, that's applied towards total.

AAMCO is NOT replacing the valve body (for a series of pretty pictures and kits designed to correct the problems, see:
http://www.transmissioncenter.net/alto_2.htm
) - after some nagging I was told they were installing the Sonnex kit.

Mine needed $1200 in parts and about $1100 in labor. After comparing the parts list with the diagram of the tranny, I'm pretty sure that the symptoms will be resolved with this repair.

What I'd like to know is if the TCC valve can be replaced without the R&R? (ie. just by dropping the pan) If so, there may be cheaper recourse for all other owners of cars that use this otherwise-nice tranny.

Cheers,
Fil

P.S. This problem (steel piston working inside aluminum cylinder => wear => leaking inside the valve body) is has been the source of the following symptoms:

* No OD engagement:
http://64.233.161.104/search?q=cache:sBfhhMXUCBgJ:www.startribune.com/stories/435/21280.html+%2Bsonnex+%2Btransmission+-sex+-HPV&hl=en
(google cache, original gone)
* Harsh 1-2 shifts:
* 1870 (slip) code:
* Other slips (related to boost pressure):

A wonderful PDF which details symptom->fault is from Cadillac website at this URL:
http://www.cadillacfaq.com/faq/answers/tsb/data/02-07-30-013c.pdf

I grabbed a copy in case it vanishes - Google also has an HTML version here:
http://64.233.161.104/search?q=cache:KJMFJrynLOoJ:www.cadillacfaq.com/faq/answers/tsb/data/02-07-30-013c.pdf+%2Btransmission+-sex+-HPV+-HIV+%2B4T65E+%2Bvalve&hl=en

As many of the later issues are a result of particles in the fluid, you should a) get your filter + fluid changed ASAP and b) resist the urge to do a "back-flush" which verywell might block some critical passage. Just do filter + fluid. Some have recommended additives (see my story, via first link).

Hope this helps someone.

Cheers,
Fil

What I'd like to know is if the TCC valve can be replaced without the R&R? (ie. just by dropping the pan) If so, there may be cheaper recourse for all other owners of cars that use this otherwise-nice tranny.

Cheers,
Fil

Fil

Did you ever get a reply to this issue? Are you referring to the TCC-PWM
solenoid/valve?

filipg

First of all all GM dealerships are required to be able to rebuild a transmission. My shop rebuilds them or replaces them depending on the price. If its cheaper to rebuild them we do so. If a new trans is cheaper we replace.

Not all dealers have a good trans rebuilder so some of them opt out of rebuilding and just do replacements but they have to be able to rebuild according to GM.

The issue you describe is with a part called the Pressure Control Solenoid or the PCS. This part is inside the side cover of the transmission. This part can be changed without rebuilding the whole tranmission or without removing the whole trans from the car. The usua charge for just the PCS replacemnet is about 5 hours of labor including the alignment.

Sorry to bring a topic back from months ago.

My question regarding this issue is resetting the taps.

Will disconnecting the battery cables achieve the same result? Since the data apparently is all stored in the PCM, and I've always had the understanding that pulling the battery cables overnight will reset the PCM, I'm wondering if that will work in replacement to visiting a dealer I really don't want to visit unless I must.

My mom's 99 Regal GS has this harsh shifting problem and I'll be replacing the PCS soon. I have a 97 GP SE, which has the 4T60E, but has no shift problems in 108K mi. Yet, it looks like from rockauto.com the 4T60E and the 4T65E use the same PCS? Why only the problems with the 65?

Thanks for the help.

Sorry to bring a topic back from months ago.

My question regarding this issue is resetting the taps.

Will disconnecting the battery cables achieve the same result? Since the data apparently is all stored in the PCM, and I've always had the understanding that pulling the battery cables overnight will reset the PCM, I'm wondering if that will work in replacement to visiting a dealer I really don't want to visit unless I must.

My mom's 99 Regal GS has this harsh shifting problem and I'll be replacing the PCS soon. I have a 97 GP SE, which has the 4T60E, but has no shift problems in 108K mi. Yet, it looks like from rockauto.com the 4T60E and the 4T65E use the same PCS? Why only the problems with the 65?

Thanks for the help.


StevePT, do me a favor and re-post in either the Grand Prix or Regal forum and I'll give you the hot rodder's trick to resetting the PCM fully and clearing TAPS (Adaptive Shift Point) data and maybe you can save a few dollars.






http://i5.photobucket.com/albums/y186/lizzywiz/regalgs.jpg

http://i5.photobucket.com/albums/y186/lizzywiz/gtp.jpg
Thrasher CAI, DHP v1.0 PCM, SLP Headers,
3.25 SC pulley, CAIT GMAF, 2.5 DP/Hi-Flow CAT,
u-bend delete, 160 TS, ZZP Stage 1 72mm TB,
TB spacer, MSD 8.5mm wires, Autolite 103,
Goodyear Gatorback Serp. & SC Belt,
Nitto NT555R Drag Radials
1/4 ET: 13.210 sec. @ 104.490 mph
0 - 60 ft: 1.945 sec.

I have mentioned here already that the same problem put me back over $ 2.000. Harsh shifting when hot. First the selenoid has been replaced, that fixed the problem for a while, than the trans quit completely. Rebuilt cost me $ 1.800 Canadian.
The guy who done the rebuilt claims that GM transmissions starve for fluid and he put more than one litre above the max. mark. The car runs smoothly now, put 4.000 km on the odometer since. I check the fluid frequently on longer trips whether it foams due to overfill, it does not.
I can see that more Buick owners experience the same problem. And we know only about those who visit this fantastic, helpfull forum.

I have mentioned here already that the same problem put me back over $ 2.000. Harsh shifting when hot. First the selenoid has been replaced, that fixed the problem for a while, than the trans quit completely. Rebuilt cost me $ 1.800 Canadian.
The guy who done the rebuilt claims that GM transmissions starve for fluid and he put more than one litre above the max. mark. The car runs smoothly now, put 4.000 km on the odometer since. I check the fluid frequently on longer trips whether it foams due to overfill, it does not.
I can see that more Buick owners experience the same problem. And we know only about those who visit this fantastic, helpfull forum.

Glad to hear your rebuilt tranny is hanging in there. Sounds like it was an expensive learning experience.

I have the same problem with my 2000 century. Started at about 36K miles, @ 50K I spent $600 to have PCS replaced by dealer, fixed the problem for about 13 months then started all over again. Decided to live with it. I now have 145K miles on the car, still have the intermittent shifting problem.

I have the same problem with my 2000 century. Started at about 36K miles, @ 50K I spent $600 to have PCS replaced by dealer, fixed the problem for about 13 months then started all over again. Decided to live with it. I now have 145K miles on the car, still have the intermittent shifting problem.

After my unhappy experience, I would not wait (if I were you) until the trans quit completely. I had the solenoid replaced than later on, the transmission quit. The guy who rebuilt it (he is over 37 years in business of restoring transmissions) said that the GM transmissions are chronically starved for fluid. He put over one litre extra (over the max. mark). Well, I am sure that guys here who work with transmissions will not agree, but I keep a close attention to the status of the fluid, during long drives. Everything now seems to be all right.
The GM transmissions are definitivelly at fault. Other than that, the car is a very good driver, on equal terms with Mercedes 300 that I used to own. Period.

My Step-mom is having same problem in a 2000 century custom, so this weekend i am attempting to change the PCS for her, i am no mechanic, i dont know if i even spelled it right but i do know a little about cars and have changed several transmissions in my life, a 1992 escort for one and the was no joke let me tell ya for a back yard mechanic like myself. But i was wondering if anybody could give me pointers and even better some directions on what i have to do to make this easy as possible from start to finish, i men what is the first step and the last. i have heard that you need the tapps reset after your done, is this something i can fix then drive to nearest dealer and have done or does it have to be done before i can drive it at all. i would greatly appreciate any help i can get on this, she cant afford the 585.00 they want to repair it so on 2/26/06 i'm gonna tare into it so please if any body can help me on the matter i thank you in advance.

Have the exact same problem with my 2000 Century. Same trouble code and same symptoms, harsh upshifts and whine from tranny varies with speed/rpm. Dealer installed a new pressure control solenoid, $680. worked great for about a year of mostly highway driving. At 80K miles started all over again. I did not invest any more money in the problem other than change fluid and filter once a year. 160K miles and still harsh shifts and the noise, but still running.

Have the exact same problem with my 2000 Century. Same trouble code and same symptoms, harsh upshifts and whine from tranny varies with speed/rpm. Dealer installed a new pressure control solenoid, $680. worked great for about a year of mostly highway driving. At 80K miles started all over again. I did not invest any more money in the problem other than change fluid and filter once a year. 160K miles and still harsh shifts and the noise, but still running.

Where are all the mechanics on this sight, do i have any takers, my deadline is getting close, only three days left. PLEASE HELP!

My Step-mom is having same problem in a 2000 century custom, so this weekend i am attempting to change the PCS for her, i am no mechanic, i dont know if i even spelled it right but i do know a little about cars and have changed several transmissions in my life, a 1992 escort for one and the was no joke let me tell ya for a back yard mechanic like myself. But i was wondering if anybody could give me pointers and even better some directions on what i have to do to make this easy as possible from start to finish, i men what is the first step and the last. i have heard that you need the tapps reset after your done, is this something i can fix then drive to nearest dealer and have done or does it have to be done before i can drive it at all. i would greatly appreciate any help i can get on this, she cant afford the 585.00 they want to repair it so on 2/26/06 i'm gonna tare into it so please if any body can help me on the matter i thank you in advance.

I hate to break the bad news to you but this is typically not a DIY job. The $585 is not a bad quote to replace the PCS solenoid. Problem is what if it is not your problem.

The PCS solenoid is located underneath the side cover assembly, driver's side of the transmission on the left hand side of the valve body. First step is to drain the ATF fluid. Every part in the engine compartment blocking your access to the side cover bolts must be removed. Items such as the complete airbox and the driver's side axle half shaft. It is a very tedious and time consuming job especially for a beginner or novice. New side cover gaskets are required.

Although it is recommended, clearing the Tapps - adaptive shiftpoints data is not neccessary after replacing a PCS solenoid but I would recommend it so the PCM can relearn. However, you will need to take it to a GM dealer. BTW - You will still be able to drive the car to the dealer providing you performed the PCS replacement properly and get everything back together.

This explains a number of issues with a couple Lumina cabs I drove as well as a rental Century I had last summer. The rental was a second-hand thing at a place that doesn't require CC's, so it had 74K on it. The cabs I had were 51K 2000 model and 108K 1999 model Luminas. All three of these shifted hard. Harsh doesn't even describe it. It's more like the transmission gives you a WOT 1-2 shift at minimum throttle. If I floored it, it seemed normal. If I pussyfooted it, it felt like I was being struck from behind. 2-3 shift was solid, and they wouldn't go into OD until well over 75mph.

All the cab company did on the cabs was flash the engine and transmission codes. It'd work fine for a few weeks then start slamming into second.

The rental I only had for two days, so I lived with it. Only had to put 30 miles on it each way to/from work and it'd start slamming as soon as i got off the highway, and only had a few stoplights to deal with between there and work/home. They said they'd fix it and that was that. At least it was only $35 a day including taxes and insurance, and I got that reimbursed from insurance later anyways.

If either of our new Luminas have this problem, this is the thread I'm saving on my hard drive so I can reference it later in case it goes away. Do 1997 and 1998 models have the 4T65E as well or is it 4T60? Also how about a 2003 Century, since my parents have one of those now? Still a 4T65E?

If either of our new Luminas have this problem, this is the thread I'm saving on my hard drive so I can reference it later in case it goes away. Do 1997 and 1998 models have the 4T65E as well or is it 4T60? Also how about a 2003 Century, since my parents have one of those now? Still a 4T65E?

This is one of the best message threads on the 4T65E autotransaxle.

On the Lumina check the SPID label located under the trunk lid or back of spare tire cover. If it says M13 on one of the data lines then it is a 4T60E.

If it has MN3 or M15 it is a 4T65E.

The '03 Century has a 4T65E. SPID label will say MN3 for the tranny code.

As I understand it, removing the side cover of a 4T65E in a 2000 Century requires lowering the driver's side of the engine/transaxle assembly so the cover is clear of the wheel well - not complete transaxle removal. As I remember my engine compartment, I'd have to remove the air filter assembly, remove the left-hand wheel and axle, disconnect the steering shaft, drain the fluid, support and unbolt the cradle then lower the drivers side carefully watching out for any other cables hoses, lines etc that may have to be disconnected that I've forgotten about.
Someone also mentioned an additive that might help fix or reduce the harsh shifting without doing all of the above. I'd try that first - can anyone recall the name of the product?

Why does it take GM a long time to fix a known problem. This valve sounds more like a design fault.

Steve L.

I'm sure GM has fixed it by now for newer 4T65E's. And recalls only apply to safety-related problems as was said earlier in this thread. So us poor owners of older cars with the problem are stuck with what we have. Fix it or live with it.

I'm sure GM has fixed it by now for newer 4T65E's. And recalls only apply to safety-related problems as was said earlier in this thread. So us poor owners of older cars with the problem are stuck with what we have. Fix it or live with it.


Perhaps.

I have a Grand Prix with the same tranny getting a new PCS. The gentleman from the tranny shop I just got off the phone with told me that the GM one they are replacing it with are prone to failure. However, the aftermarket ones are just junk too.

I guess its a lose lose situation for us 4t65e owners...:lol:

I have a 2002. Anyone know if this tranny has been redesigned to fix this problem? If it was redesigned, what year was the fix done?
Thanks
Steve L.

I have a 2002. Anyone know if this tranny has been redesigned to fix this problem? If it was redesigned, what year was the fix done?
Thanks
Steve L.

Probably not. Are you having any problems?

The applicable GM TSBs on this problem covering the harsh shifting/shudder/DTC 1811 and PCS replacement on the 4T65E are:

TSB # 00-07-30-002B Issued July 2002

TSB # 02-07-30-048 Issued November 2002

Bob, I believe GM has changed the supplier for these solenoids.

Bob, I believe GM has changed the supplier for these solenoids.

I wouldn't count on that Max. I know of 2002 and up "W" body owners with the 4T65E tranny having PCS solenoid problems.

I wouldn't count on that Max. I know of 2002 and up "W" body owners with the 4T65E tranny having PCS solenoid problems.


I concur.

If the gentleman I talked to is correct and new GM solenoids for the 65E are still prone to failure, then I doubt they changed the supplier.

Should have an answer soon got a buddy in GM tech from my old days with Cadillac.

Should have an answer soon got a buddy in GM tech from my old days with Cadillac.

According to the GM and AC Delco info I have the PCS solenoid did not change nor was it improved until the 2003 model year. For 2003 and up the PCS part number changed too. It is 24225825.

The 2000 - 2002 model years have the same PCS solenoid, part number 10478146. Therefore, based on my info 2002 models are subject to PCS solenoid failures.

thanks guys,
I don't have a problem with my 2002, but now I'll keep an eye on it.
I guess that means that they will replace the PCS with the new version and the problem will go away. Or is it that for the 2002 and older they must replace with the older PCS because of fit?
Steve L.

According to the GM and AC Delco info I have the PCS solenoid did not change nor was it improved until the 2003 model year. For 2003 and up the PCS part number changed too. It is 24225825.

The 2000 - 2002 model years have the same PCS solenoid, part number 10478146. Therefore, based on my info 2002 models are subject to PCS solenoid failures.
Geez, Bob, I never have any fun no break even for a "senior citizen", you are on the money, just got the same info, we still don't know if they are now " fail safe"

Geez, Bob, I never have any fun no break even for a "senior citizen", you are on the money, just got the same info, we still don't know if they are now " fail safe"


Sorry about that Max and for spoiling your fun. Thanks for the confirmation on the PCS.

How's that new Le Sabre?

I have a 2002 Regal that has the same symptoms. Shifts normally until it has been run for several miles. Using my laptop I have correlated the onset of harsh shifting with both the transmission pressure control solenoid actual and reference currents going to zero and staying there!!!???? I am going to review the schematic and see if the cause could be a short or the like in the vehicle wiring harness...