2000 GT shifting really hard

**WhiteGT** · 06-03-2009

I am interested to know what this computer update is/does. I have not heard of this and am interested to know if mine has been done. I just had my pressure solenoid replaced but the trans still feels like it could shift alot better than it does.

**NoTyme** · 06-03-2009

Originally Posted by NoTyme

My first step is having the filter changed and new fluid today: Will test drive and see if we can reproduce the hard shifting. If not, I am not sure which way to go...

Update:

Had the filter changed and new fluid added. Mechanic said filter was dirty and that a plug had a lot of material attached to it. He recommends a filter change and new fluid over back flush.
So far so good after 200 miles.

**NoTyme** · 06-25-2009

Originally Posted by NoTyme

Same issue on my wife's 02 GP GT

I have a friend who is one of the best mechanics in town, and he said change the filter, fluid and clean the valve body etc. Give it a few hundred miles and see if it doesn't stop:
Well; it stopped immediately...

It has only shifted hard about 3 times since, but after 250 miles we are still waiting for it to work the fresh fluid thru it. This is a good place to start for anyone having this issue... He recommends skipping the tyranny flush.
You can listen to his advice on WJR radio on Saturday mornings on "The Car Show"

**c002529** · 07-14-2009

If my issue is the pressure solenoid, is there any real negative impact if it isn't fixed right away?

**NoTyme** · 07-14-2009

Originally Posted by c002529

If my issue is the pressure solenoid, is there any real negative impact if it isn't fixed right away?

I really don't have an answer for that, but you can always try to call in on the Car Show on Saturday mornings and ask that.

continuing update: car has only shifted hard 2 or 3 times since fluid, filter and valve body cleaning... I think its working.

**gtryda** · 07-15-2009

My 1999 grand prix gt doin the same the with the hard shifts took it to a shop and they said i needed my transmission rebuilt or replaced never mentioned anything about a solenoid that could of caused the problem

**NoTyme** · 07-15-2009

Originally Posted by gtryda

My 1999 grand prix gt doin the same the with the hard shifts took it to a shop and they said i needed my transmission rebuilt or replaced never mentioned anything about a solenoid that could of caused the problem

I'd get another opinion... You should read my post above; I like starting off spending the least amount of money as possible and work my way up to the solution. Not sure of your mileage but if you have flushed before, try replacing the filter next. While in there drop the valve body and clean it also. This is something any backyard wrencher can do.

**gtryda** · 07-16-2009

Thanks man but im not to good up under the hood i can do a few things but when it comes to my transmission ill look dumbfounded up under there the car has 174,000 plus miles on it i had it a lil over 2 years and never had a transmission flush or changed the filter could that be doin the problem?

**c002529** · 07-16-2009

Took it to a shop and hard it scanned and they told me it was the EPC aka pressure solenoid. $550 out the door. Taking to another guy for a second opinion.

**GTPJOE90** · 07-18-2009

o lord

**c002529** · 07-18-2009

Taking it for a second opinion on Tuesday. Just to make sure this guy says the same thing. He is also going to pressure test it.

**c002529** · 07-21-2009

Got my second opinion today. Guy said it was pressure solenoid for sure and he was going to change it, the filter and clean the valve for $450.

**fischelr** · 07-29-2009

I feel (literally) that I have the same issue.

Background:
98 GP GT
140K
no mods under hood
never had tranny fluid touched before my filter/lube change about 3 week ago
tranny sliped after red line from first to second before change

Issue:
Changed tranny fluid and filter. Everything seemed to be running same/better after change. Drove about 250 miles on car through hills with lots of downshifting, everything ran smoothly.

Got home from trip drove to work, everything fine. Left work later on that day (about 83 degrees out) got almost home (about 10 miles), and WHAM between first and WHAM between second. Hmm, that's not good.

Summary of issue:
Car runs fine when cold, get's hot and will run good for about 10-15 miles, starts to shift hard between 1 and 2

However, if I shut the car off, let it sit for >30 seconds, car shifts fine for about 4-5 miles.... Wierd right??

Has anyone heard of this? Is it possible that when I dropped the pan Mr.Computer did a back flip? I understand there are GM software upgrades, any idea on cost? Is it probable to think I screwed up the oil change? I added 8 quarts of Dextron III oil, and about 1/2 quart of some additive (after this problem started, and it did extend the time till hard shift). Level looks good, when checking warm the fluid comes up to the criss-crossed lines on dip stick (am I reading the dipstick wrong?). BTW, I took out a little less than 8 quarts from car.

However, I should mention that I do see bubbles on dipstick when car is hot? Am I over filled even though the dipstick says I'm not?

Addition: have been reading through some other threads, just un hooked ground wire to battery (computer issue?). Also, got some advice from a friendly co-worker that there may be some blockage creating the back pressure. Would a flush be a good start?

Thanks for your help, hope I was descriptive enough.

**c002529** · 07-30-2009

Was the tranny shifting hard before the fluid change? Also, have you had it scanned at a shop yet? Most of them do it for free and it doesn't take very long.

**fischelr** · 07-30-2009

Once, about a year ago, it did this. I switched off the engine, restarted, and was not an issue until now.

I called one local shop, he said $75 for the scan, and if there is a problem, he takes the $75 off the total cost of repair (what's $75 after a $3000 repair).

Can I confirm that I am reading my dip stick correctly. I.E., when warm, the fluid should rise to the crisscrossed line on the atf dipstick?

Also, is it common to see some bubbles on your dipstick when warm, or is that a dead giveaway to an over/under fill?

Thanks guys, I appreciate the help, hopefully you can help me save a few bucks.

**halfwit** · 08-01-2009

I have basically the same issues as fischelr. 2000 GP. No mods. My issue started last week with a whine at highway speeds, then I noticed a bit of a hesitation when I was on the highway if I let off the throttle gave her gas. It would take a second for the tranny to catch. This evening on my way home she started to hard shift between first and second, then second and third. Tranny fluid is nice and clean, and topped right up. I will have to take it in next week to have it pressure tested. Please let it be a switch!!! Based on everything I have read, I am hoping that is what it is.

**Blacknight02GT** · 09-10-2009

I have an 02GT with what seems to be the same problem. It is fine most of the time.. but every couple weeks when i'm drivin in hot weather for at least 10-15 miles it will begin to shift hard in 1st to 2nd then 2nd to 3rd. Now, I never had this problem before I had the Transmission Fluid Flushed and Filter changed 2 months ago. However, I left the shop that day with my fluid only half way filled and noticed on my way home the same type of hard shifting. I took it back furious and they topped it off. Car was fine for about a week, then it started the hard shifting again.. Took it back furious still.. did a pressure test and reflush added conditioner everything seemed fine. about 2 weeks later BAM hard shifting again on a long trip I took on a hot day

So I think now my problem could be this Pressure Control Solenoid. My question is Could this problem have been caused by underfilling the tranny fluid by the shop, or was it just a coincidence??? SHould i go after them for the Money to fix it? is it not their fault?

**JGT010** · 09-10-2009

It could be their fault, hard to say for sure and it might be hard for you to prove. In other words could you show that your car shifted in a text book fashion prior to them changing the fluid. Its true that low fluid level can be detrimental to any transmission. It depends on how long you drove it without realizing the fluid was low if would have caused your problem assuming your car shifted great before. Now about the hard shifting. I've had a similar problem in my 07 GT, It seems that my car shifts rather hard from first to second when I am making a turn. I slow down to make the turn and as I accellerate out of the turn it seems to shift rather thats the only time I notice it. Accellerating from a straight stop from a light or stop sign it shifts normally. There is pressure control Solenoid in these cars and they can be troublesome causing crappy shifting in the lower gears, also the factory shift points are soft to start with and long in duration which I don't like. You might want to ask around but you might want to have a new pressure solenoid installed and maybe a shift kit as well. Oh, long drives in hot ambient temperatures can sometimes affect shift quality. Don't let anyone talk you into a rebuild just yet though. Hope this helps.

**Blacknight02GT** · 09-10-2009

Originally Posted by JGT010

It could be their fault, hard to say for sure and it might be hard for you to prove. In other words could you show that your car shifted in a text book fashion prior to them changing the fluid. Its true that low fluid level can be detrimental to any transmission. It depends on how long you drove it without realizing the fluid was low if would have caused your problem assuming your car shifted great before. Now about the hard shifting. I've had a similar problem in my 07 GT, It seems that my car shifts rather hard from first to second when I am making a turn. I slow down to make the turn and as I accellerate out of the turn it seems to shift rather thats the only time I notice it. Accellerating from a straight stop from a light or stop sign it shifts normally. There is pressure control Solenoid in these cars and they can be troublesome causing crappy shifting in the lower gears, also the factory shift points are soft to start with and long in duration which I don't like. You might want to ask around but you might want to have a new pressure solenoid installed and maybe a shift kit as well. Oh, long drives in hot ambient temperatures can sometimes affect shift quality. Don't let anyone talk you into a rebuild just yet though. Hope this helps.

Well, I don't really know how to prove that the car shifted fine before, all I have is that I went back to the shop the same day because it was shifting really hard in all gears b/c it was low on fluid. They apologized and filled it.. and I went back a week or so later with the same problem after i took a long trip on a hot day. This doesn't happen very often, only when its really warm out and I've been driving for a long time and the engine temp is up high. It just seems to slam into gear; but if i shut the car off for 30 sec or so then restart it; the car is fine.. shift smooth as the day it was new. idk why. The solenoid does make sense, and i'm leaning toward that. I'm just pissed if it happened because of the botched up fluid change job by the shop. I don't know how i could prove it though. And Hell no, i most certainly don't need a rebuild. The trans itself is perfectly fine otherwise and shifts really well. I'd have a law suit with that shop before I had to do a rebuild

**JGT010** · 09-11-2009

Well we all know heat is detrimental to Trannys. I live here in SE Louisiana and I am always concerned about Tranny and engine Temps. Besides the T465-E Trannys in these cars are somewhat quirky.