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