4L30E Transmission in Isuzu Trooper


Need advice please.

2001 Isuzu Trooper Limited, 4wd., about 110K miles.
Transmission fluid is full, smells and looks good.

A few years ago the torque converter exploded and I had that fixed.

Then transmission started taking a long time to shift into reverse in the morning, this has continued and has become progressively worse.

At some later time I began having intermittent shuddering, grinding with loss of power. It always sounded to me like the Park Pin was trying to engage, but no-one could ever diagnose. At first the noise occurred when the truck had been sitting for a bit, and was within the first mile or so. As it progressed it occurred randomly at any time. Then one day it suddenly stopped.

Shortly after that I unfortunately had an accident, I rear-ended a car at low speed, <10 mph. No damage to the Trooper, but maybe related?

Then shortly after that, while on the freeway. Slowed to a stop due to traffic, then the truck would rev up but the transmission slipped. I could slowly get to 15 mph and after that the transmission was relatively OK, but felt “soft”.

Current symptoms.
Takes a long time to shift into reverse.
Transmission is slipping in D, D2, D3 etc ranges and has essentially no grab. Undriveable from a stop.
Transmission works fine in R and L.
Can currently move it if necessary by starting out in L, then shifting to D range, but it’s still “soft” in D range, becoming more normal in feel at higher speeds, and seems almost normal at freeway speeds.

Web searches indicate possibly 1. Range Sensor, 2. Solenoids, 3. Belts.

Local repair shops are hopeless and I will not return to the shop I used previously.
Acura denies that they ever sold Troopers with an Acura badge - never mind that they did this for 2 years as their first truck and that I saw one just last month!
I think this is a fix it myself task.

I can clean the range sensor, if I can find it.
Not sure if I can source the solenoids, how to specify them, where they are, if I can do this with regular tools or if it requires some specialty tool.
Belts are beyond my capabilities.

Please advise if any of these scenarios are probable, it’s something else, or if I am donating this to Public Radio… AND how to proceed if you can identify a likely cause - i.e. location of these things on the truck, how to correctly specify the new parts, where to purchase, etc.

I have a mechanics manual for the 1992 Trooper, but not for the 2001. These are essentially the same vehicle. (1992 Trooper was lost to Tropical Storm Alison and is no longer with us, so I can’t use it for parts.)

I don’t want to spend a lot of time/effort/money on this, but it is really nice having a beater truck for those (many) chores where I don’t want to use the brand new Land Rover.

Please respond if you solid experience with the 4L30E transmission. No speculations please.

Many thanks!



“No speculations please.”
Since none of us can see,hear, or drive the vehicle, about all you will get will be best guesses and speculation. Best of luck.
“Web searches indicate possibly 1. Range Sensor, 2. Solenoids, 3. Belts.”
Sounds like you got it covered.
"but it is really nice having a beater truck for those (many) chores where I don't want to use the brand new Land Rover."
Yeah it is, but you're going to have to get the Rover dirty sometime. Sorry, but if I can't speculate, that's all I got.

Yep, speculation is pretty much what is done here, but its free speculation.

I speculate that unless you’re experienced at transmission repair (probably not or else you wouldn’t be asking the question here), it’s going to end up taking more time than you want to spend on something that’s “nice” to have and not your only vehicle.

At some point in time, this thing must have been scanned for error codes. These may be generic OBDII error codes that would turn on the check engine light and can be read by generic scanners. Or they might be GM specific transmission codes that won’t turn on the engine light and access requires GM Tech II scanning capabilities.

So if it has been scanned for error codes, then post them - format “P0123” If it hasn’t been scanned for error codes - well, that’s the first step. You will almost certainly incur a basic diagnostic charge, frequently equal to an hour’s labor.

The manual from the '92 may or may not be all that helpful. The computer control systems are completely different.

This is NOT speculation. Take it to AAMCO they will tell you a rebuild is necessary, and by coincidence they will just happen have a freshly rebuilt unit the shelf. Problem solved.

How do these people even find an old thread like this and I guess they don’t have a life . Another reason that threads should be closed after a period.


I had completely forgotten about this post. The transmission shortly thereafter failed completely and only worked in reverse. I donated the truck to PBS. I would be happy to close this discussion, but at least right now, I can’t seem to find how to do that.

@PvtPublic Why don’t you edit your post and take out the inappropriate comment that was flagged and removed? Otherwise you just managed to keep it live.

As far as the trans goes, when the converter blows, it sends junk through the transmission and that transmission needs to be rebuilt and cleaned. You can’t just replace the converter. Not speculation-been there.

Yeah that’s what I meant. I understand your reaction but thought Jody’s comment best be gone.

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