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2002 4x4 trooper - transmission problems: info for others

14K views 17 replies 8 participants last post by  willdieh 
#1 ·
Hello all,

I just wanted to post my recent experiences with my transmission so I could perhaps be of use to others.

History:
Just bought a 2002 4x4 trooper with about 92,000 miles on it about 2 weeks ago. After I got it home, the transmission slipped on my inclined driveway. Had to add about two bottles of fluid.
Began driving it daily and noticed the following transmission problems:

Engine braking would surge. Seemed like the transmission was slipping during engine braking; the tach would drop and then the transmission would catch and it would raise back. This would repeat and repeat during deceleration.

3->4 would cause a noisy rattle at low speeds (30mph). Sounded like a "b-r-r-r-r," was pretty loud, and could be felt. Happened under very slight load/acceleration just after the shift at low speeds. Also typically followed by some brief flaring on the tach until the transmission would "catch" again and it would drop (only 1 sec or so). The sound seemed to be coming from the front of the transmission.

I did a fluid change (pan drop only). Didn't change anything. The fluid was really dark and nasty... But the magnet didn't have any metal shavings on it (just some metallic "sludge").

This car came with a 30 day warranty on the engine and transmission but the seller/dealer was pretty iffy. I bought it from a certain area in Anaheim which might be enough for some to know what I mean. I bought it expecting some problems (it had some overspray from a re-paint and some hammer marks on the inside of the hood) but got a good deal on it so I bought it.

I took it to a local shop and they tried to tell me there was a problem with the transfer case. Never had any problems with 4x4 though, and the t-case is BEHIND the transmission while the sound came from the front so I was very skeptical.

After fretting about it for another week, and not having the time to take it to another shop for a diagnostic, I decided to act on my own theory and try to troubleshoot it.

My theory is that something was either vibrating or engaging/disengaging rapidly at the front of the transmission. This left the gears or the torque converter clutch. The transmission shifted fine and didn't slip (except for engine braking) at normal speeds, so I felt the gears and clutches inside the transmission were fine. Also, when in power mode, there was no problem whatsoever (probably because the shift point of 3->4 was raised high enough to prevent the problem). So I figured it was the torque converter. Either it was vibrating in there or the torque converter clutch was bad/wrong type.

Apparently in 1999 or 2000 (not entirely clear which), the 4L30E was equipped with a PWM (pulse width modulation) torque converter clutch solenoid that pulses the torque converter clutch rather than just an on/off state. Not really clear on the whole reason "why," but there are differences between both the earlier solenoids and the earlier TCC materials (did I read later models use teflon? for better durability?).

One of the weird things the dealer told me was that he replaced the torque converter before selling it. "Why?", I asked. "To make it go faster," he said. Okaaaaay. Anyway, that (and the fact that he said he put new shocks in which he did not) sort of nagged in the back of my head. Did he put in the right torque converter? Is it just a bad torque converter? What's up with that torque converter?!

So anyway, I dropped the front pan (the 4L30E has two pans) and disconnected the torque converter clutch solenoid. It's the one on the driver's side of the car. The connector was very brittle and I cracked/broke off both clasps on the connector removing it. It'll probably still work and stay on, just won't lock on :( I don't think it could have been avoided and shame on GM for not putting the clasps on the $30 solenoid instead of the connector wire.

Now my car would drive without any torque converter. I actually removed the solenoid and tested it. The ohm resistance as 12.xxx and it seemed to function when connecting it to a 12v battery. I put it back in (without connecting it) and drove around for about 20 mins.

No more weird sound, no more weird shifting. Actually, the 3->4 shift was barely even noticeable. I actually shifted to 3 a couple of times to make sure there was any actual difference. Without the Torque converter clutch, there's definitely a lot less power but no problems at all! No more vibration, no more noise, no more slipping!

So, now I have to get a hold of that guy and ask him to replace the torque converter, the solenoid, or both. (I can replace the solenoid, but hope he'll replace the torque converter so I don't have to drop the transmission).

The moral of the story... If you're wondering if you have a slipping this or shuttering that, just try dropping the small transmission pan, disconnecting the driver side solenoid (TCC) and drive it around. It's an easy way to eliminate what I found to be common symptoms ("shudder") in several posts here.

Weird thing is, I still don't have any transmission error codes on my car. Never had one during the initial problem, don't have one without a TCC! WEIRD. The dash light works during start up, but goes out and doesn't light up during driving.

Anyway, hope this info was useful to someone out there.

When you drop the pan, it's going to get fluid EVERYWHERE :( I had just started the car, so maybe that's why. Maybe try jacking up the front and hope it drains back a little, then lower the front before removing. I used a floor jack to support it as it came down. Didn't use any floor jacks to jack up the car. Just need a 10mm for the pan, 11mm for the solenoid (if you're going to even remove it; could just disconnect it), and lots of paper towels/rags.

Good luck!

William
Grand Terrace, CA
 
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#2 ·
Excellent post.

The being 2 qts low on your transmission could've caused it's own problem; the 4L30 does not like to be the slightest bit low, it'll cook fast.

Hopefully when you replace the part the problem will go away; however, depending how long it was driven being low on ATF, it's hard to say if it will completely shift right again, for the long haul.
 
#3 ·
Anybody care to voice their expert opinions on the ramifications of driving extended distances (50 miles) without a TCC?

I figure the old cars did it before TCCs were common, so it shouldn't kill anything.

One thing I'm worried about is heat... one of the purposes of the TCC is to prevent heat.

But I have to drive that far to get it back to the dealer.

Thanks!
 
#5 ·
Please let us know the outcome! I am very curious about this issue. I am having hard shift issues and your problem could be some of mine. Really got me thinking about those shift solenoids. Where did you find your info on these transmissions?? Please share. Best of luck with your dealership.
 
#6 ·
I just wanted to post a follow up to this story. After replacing the torque converter (myself; dealer game me $500 for my troubles) the transmission is behaving very nicely now. No problems at all during normal shifting.

I still have one problem but I'm not sure if it's transmission or electrical. More likely the former I suppose. When coasting at over 2000 RPMs or so, the engine braking doesn't seem to hold. It seems to go in and out of gear until the RPMs drop to a lower point then it straightens out just fine and the transmission holds until stopping.

Anyway, if you have weird issues in 4 at low RPMs, just after an upshift, try working on your torque converter :) Try disabling the TCC solenoid and go from there if it looks like a positive change.

-William
 
#7 ·
William, I woild like to know just what is engine breaking? I posted the problems i am having and have not had any professional folks reply.

Here on your post there are some things the same that are happening with my 2001 2wd trooper.Happening under very slight load/acceleration just after the shift at low speeds. Also typically followed by some brief flaring on the tach until the transmission would "catch" again and it would drop.
This will sometimes also happen going up a slight hill going 70 on the interstate. The shuttering also seems to happen after leveling off with the speed I am driving.

Here is my entire post, maybe you can help me figure out if I just need to change out my solenoids.

We have a GM 4L30E Transmission that is shuttering in 2-3 & 3-4 in over drive. This is completely rebuilt with all new parts with only 40,000 miles on it. Changed the oil & filter & added Dr tranny shutter fix, Worked for 2 weeks & now shutter is back. Are there things I can check before replacing the solenoids? Where do I look to find the best prices on these solenoids? Does anyone have any suggestions as to what else we can check other than the solenoids? THANKS SO MUCH!!! Walter & Kathleen
 
#8 ·
well, it's pretty hard to say if we have exactly the same problem. the purpose of my post was really to recommend people disconnect the torque converter solenoid for testing if they suspect the torque converter clutch.

in our case (post 2000 troopers), i'm very suspicious of shops putting in the wrong torque converters. after 2k, the torque converters changed and started using a different clutch material and solenoid. if a shop puts in the wrong kind of torque converter, it's possible it might slip, shudder, etc.

if you disable/unplug the torque converter solenoid, you can test to see if it was the cause or not.

engine braking is when you're slowing down and the engine is providing the resistance to forward motion.

a cheap place for solenoids might be ebay. you can get a whole throttle body with solenoids for pretty cheap. they'll be used but might be good enough for testing. the cheapest place i could find was transmissionpartsusa.com. i bought a torque converter solenoid from them but it didnt fix my engine braking issue.

-william
 
#9 ·
willdieh, I'm a newbie, but have read almost all posts in the last two days trying to pinpoint my problem. What brand torque converter did you replace yours with? My '97 Rodeo does the same "shuttering" sound at take off. Also when first starting and putting into gear, it will go in and out of drive while sitting still, or when trying to go. Almost like electrical...like on..off...on...off... Very strange, but makes me think its the torque converter, or the selenoid, after reading your post. ???
Thanks,
dwo

willdieh said:
well, it's pretty hard to say if we have exactly the same problem. the purpose of my post was really to recommend people disconnect the torque converter solenoid for testing if they suspect the torque converter clutch.

in our case (post 2000 troopers), i'm very suspicious of shops putting in the wrong torque converters. after 2k, the torque converters changed and started using a different clutch material and solenoid. if a shop puts in the wrong kind of torque converter, it's possible it might slip, shudder, etc.

if you disable/unplug the torque converter solenoid, you can test to see if it was the cause or not.

engine braking is when you're slowing down and the engine is providing the resistance to forward motion.

a cheap place for solenoids might be ebay. you can get a whole throttle body with solenoids for pretty cheap. they'll be used but might be good enough for testing. the cheapest place i could find was transmissionpartsusa.com. i bought a torque converter solenoid from them but it didnt fix my engine braking issue.

-william
 
#10 ·
dwo,

your problem sounds more like the range mode sensor (electrical). Try searching for that on these forums. There are alot of threads about cleaning this sensor because of bad shifting.
 
#11 ·
No, unfortunately not... Believe me, I've cleaned the existing one and replaced it with two others without any change.

The whole thing seems to be due to low fluid pressure. I finally bought a pressure gauge and was getting 10-20psi lower than spec on the test port while driving. So, I'm pretty sure that was it - the pressure is too low at idle/coast to get the TCC to lock up.

I've got a replacement transmission I bought and will put in soon. Then I'll rebuild the existing one :) Hopefully it's not the oil pump, as I believe the 2000+ ones are expensive or something.

Thanks for the reply though!

-William
 
#12 ·
sorry willdieh, I was talking to dwo. I believe you 100% on your problem. You seem to have thoroughly inspected and researched your issue. Please keep us updated on all your progress.

dwo's problem just seemed that it could be range mode switch related. 2 cents.
 
#14 ·
willdieh said:
No, unfortunately not... Believe me, I've cleaned the existing one and replaced it with two others without any change.

The whole thing seems to be due to low fluid pressure. I finally bought a pressure gauge and was getting 10-20psi lower than spec on the test port while driving. So, I'm pretty sure that was it - the pressure is too low at idle/coast to get the TCC to lock up.

I've got a replacement transmission I bought and will put in soon. Then I'll rebuild the existing one :) Hopefully it's not the oil pump, as I believe the 2000+ ones are expensive or something.

Thanks for the reply though!

-William
I had no idea you could buy something to test your tranny PSI.. Where did you get it, how much was it, and where did you install it at?!
 
#17 ·
Lots of info here... My 2002 Trooper transmission is fine but I do need to put some fresh fluid in. Have 91k miles and is runs good but I'm sure it will like some fresh fluid. With all the talk within this thread I thought there might be some updates out there... So if anyone has more tips on what I should do when I drop the pan or drop the small pan and clean anything just let me know. Appreciated! Thanks -
 
#18 ·
Well, no updates from me... I still have the problem. After all my work, I figured it's either the pump is bad (low psi) or the Torque Converter is bad. The Torque Converter Clutch is, I believe, causing all the trouble. It's not able to properly lock on deceleration due to low fluid pressure.

No biggie for me. I'm just living with it. I bought a used transmission for $100 (lucky) that's standing by just in case. But haven't had any problems other that that.

Good luck!
-William
 
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