Isuzu SUV Forum banner
1 - 20 of 21 Posts

·
Registered
Joined
·
228 Posts
Discussion Starter · #1 ·
I have a 1991 Isuzu Trooper II with V6, 2.8 L, 4WD, Automatic with 188,000 miles on it. I got the transmission rebuilt recently. A couple of times, after the car was warm, I restarted the car, and a gear would not engage - the RPMs would just go up instead of changing gears. This was a few days after getting it fixed. First time happened was three weeks ago with the third gear, after I'd driven a ways, stopped and visited someone, then drive off again. But then is was fine in the intervening weeks (had a connection to the ECU which was loose and causing the Check Engine light to come on repaired - not sure if that's related). Second time was today, after I'd stopped and pulled over to take a phone call. When I started again, it could not get out of first gear until I pulled over (with out shutting off engine), then it started working again.

The problem is it will work after that, so the transmission mechanic can't troubleshoot it. He wants to know what triggers, what conditions it happens under so it can be reproduced. But I can't reproduce it on demand.

He doesn't think it's likely that it's a mechanical problem, because then it would consistently not work. Rather he thinks it's more likely a electrical issue.

Could it be the transmission computer or a connection? There were various burned/worn out parts in the transmission that seemed to be the cause of the original issue.
 

·
Registered
Joined
·
1,406 Posts
Given that the problem goes away once you shut off/restart the trooper, he's possibly right about it being a computer/electrical problem. The only part that doesn't make sense is that it resets and works fine without shutting off the engine. If it were a little more consistent, I'd wonder if the mechanic got the band(s) adjusted properly. I'm not familiar with this transmission (4l30E, right?) or I'd have more ideas. But being computer controlled, seems to me it would be tossing an error code if it were an actual ECM malfunction....maybe even if it were just a bad/broken/burnt wire.

The problem with something like this is that your mechanic will probably be very unlikely to admit that he screwed something up, so if that's the case, it will probably take a very, very long time to figure it out and fix it.
 

·
Registered
Joined
·
11,917 Posts
A 91 Trooper with 2.6 L engine usually has a A340H ASIN transmission which uses a Transmission Control Unit (TCU) that performs gear selection by electrically operating shift solenoids located in the transmission. It is possible you have an electrical problem. What was the symptom before you had it repaired?
 

·
Registered
Joined
·
228 Posts
Discussion Starter · #4 ·
First of all, it's the 2.8 L engine (V-6), not a 2.6. And I checked - it does have a Bosch TCM.

The symptoms before the rebuild was that it was slipping in 3rd gear (not going into gear), and maybe 2nd. One mechanic claimed when he smelled the transmission fluid that it smelled burnt. I added some Lucas Transmission Fix, and it got much worse (after it warmed up) and I had to have it towed home.

The transmission rebuild shop had if for about 3 and a half weeks. The first time they put it back together, they didn't have a coupling on well enough and it leaked tranny fluid. Then they had to take it apart again he said because they found a worn plastic shim, there was a crack in it, the pump sits in the drum, grinds. They replaced the bushing. The receipt says they replaced 3rd gear drum, a center support bushing, oil pump, torque converter. Anyway, they had to take it apart a third time because of what they thought was a solenoid problem. Not sure what the upshot of that was - I think he said they found it was OK.

Anyway, when I picked it up, he said the engine light was coming on. It was also running very rough because a spark plug wire was partly pulled out (I discovered). My regular mechanic eventually fixed the engine light by finding it was a connection to the ECU that wasn't solid (after he'd replaced the oxygen sensor). The transmission mechanic also had left a shim out of the starter and I had use quite a bit of persuasion to convince them that it sounded loud and different and look at it, and then they put a shim in.

It also sometimes shifts hard into third gear in particular (clunk!). But that's not consistent either.

I understand him not wanting to take it apart again after all that work . I don't want them to either if I can avoid it, after all this. Makes me nervous!
They did give me a 12-month/12,000 mile warranty though.
 

·
Registered
Joined
·
11,917 Posts
I don't know why I typed 2.6 L when you clearly stated 2.8 L, but more importantly can you confirm the vehicle has an ASIN A340H transmission as opposed to the GM 4L30e found in later year models.
 

·
Registered
Joined
·
228 Posts
Discussion Starter · #6 ·
This model has the GM 4L30E. This is according to the transmission mechanic and this entry I found:
"On long wheelbase models, the GM 2.8L V6 (LL2) is introduced as an option as well as the 4 speed GM 4L30E automatic transmission, available on the 2.8L V6 only as the 4ZE1 2.6L was paired with the A340H - an Aisin transmission." from http://wiki.planetisuzoo.com/index.php/Troopers
 

·
Registered
Joined
·
2,672 Posts
I could tell right from the start it wasn't the asin trans because he was stating he had a problem with his trans.

I have to say that its probably just a loose wire connection at the trans or a dirty or misadjusted gear position sensor. My friend had similar problems with the 4l30e in his 3rd gen trooper, turned out to be the wire harness wasn't secured well enough and fell and landed on the front driveshaft and wore thru the insulation and shorted the trans out. It was an easy fix but initially he thought he got screwed by the trans rebuilder and his $2600 recent trans overhaul bill.
 

·
Registered
Joined
·
11,917 Posts
The 4L30e uses two electrically controlled shift solenoids, the wiring for these solenoids goes through the 4 Pin connector on the main transmission case. Additionally, the band solenoid control signal goes through this connector, if it is inoperative you can get harsh 3rd gear operation. Recommend you check the wires going this 4 pin connector for damage or loose pins.
 

·
Registered
Joined
·
1,406 Posts
caveman said:
I could tell right from the start it wasn't the asin trans because he was stating he had a problem with his trans.

I have to say that its probably just a loose wire connection at the trans or a dirty or misadjusted gear position sensor. My friend had similar problems with the 4l30e in his 3rd gen trooper, turned out to be the wire harness wasn't secured well enough and fell and landed on the front driveshaft and wore thru the insulation and shorted the trans out. It was an easy fix but initially he thought he got screwed by the trans rebuilder and his $2600 recent trans overhaul bill.
WIth a $2600 bill? Oh yeah, he got screwed. You can go buy 2 decent running troopers and 200 gallons of gas with that money kind of money. A "reasonable" bill for a tranny rebuild based on realistic costs for parts and labor (including R&R) would be between $900 to $1500. Seems like almost any mechanic will rob you these days.
 

·
Registered
Joined
·
228 Posts
Discussion Starter · #10 ·
Thanks for the ideas. I'll have him check it out.

Is it hard to get to that connector or those sensors? They won't have to take the transmission out will they? Is it something I could see from under the car - anybody have a diagram or photo?
 

·
Registered
Joined
·
11,917 Posts
The 4 pin connector is on the left side (driver US) of the transmission case. The Range Mode Switch (RMS) is attached to the transmission gear select lever also on the left side of the transmission. If you crawl under the vehicle you can see them.

There is an image of the (RMS) in this thread : viewtopic.php?f=17&t=1707&start=50
 

·
Registered
Joined
·
228 Posts
Discussion Starter · #12 ·
Well the intermittent hard shifting into third would seem to support the idea of a poor electrical connection too. Also I noticed that it started doing the hard shifting into third again after he had it up on the lift the last time. I was asking myself "What the heck does putting it up on the lift have to do with triggering this again?"
 

·
Registered
Joined
·
11,917 Posts
The 4 pin connector is wired as follows :
Pin A-----2-3 (Shift B) solenoid control
Pin B-----Band solenoid control
Pin C-----+12 VDC solenoid supply
Pin D-----1-2/3-4 (Shift A) solenoid control

The TCU will ground Pin A, B, D as necessary to energize the solenoid to control gear selection and band application.
 

·
Registered
Joined
·
228 Posts
Discussion Starter · #14 ·
Great (where did you find this information?). So now my plan is to take it into the transmission shop, have him put it up on the lift again, and bring in my can of contact cleaner I use for fixing computers, and pull off and clean the connectors down there. I suppose if cleaning the connectors (or seeing anything else obviously wrong with the wires) doesn't help, then somebody will have to trace/troubleshoot the wiring.

So what are the connections I should look at? Obviously the 4-pin connector, and take a look at the Range Mode Switch (RMS). What's involved in checking out the RMS - taking it's cover off and doing a visual inspection?

Thanks Again!
 

·
Registered
Joined
·
11,917 Posts
The RMS is actually six switches in a single package. Four switches are used to set up a 4 bit binary code as the input to the TCU to represent the 7 actual gear selection positions. One switch operates the backup lamps in Reverse and the remaining switch the starter solenoid relay in Park/Neutral. The switch assembly consists of copper foils and a slider that selects the appropriate output. The cover is not dirt/water proof and the foils can become dirty. If any one of the 4 inputs to TCU is open the TCU has no idea what the gear selection is. To clean it remove from the vehicle, remove the cover, apply contact cleaner and a thin film of DC4 dielectric compound and put it back in. You can check the functionally of the switch with an ohm meter or apply the +12 VDC to the power input and check the voltage out on the each of the pins. Info on all this is available in the forum.
 

·
Registered
Joined
·
228 Posts
Discussion Starter · #16 ·
It's been acting OK recently - I've drive it a few times and no problems with the transmission. But I took it in and had the transmission guy clean some contacts. He was able to find the 4-pin one mentioned in the posts above, and one with 5 pins, and pulled those off, sprayed some of my contact cleaner in them (the stuff I use for computers) and put them back on. (The RMS looked different from the one in the thread referenced, and was a sealed unit, so I didn't think it worth the trouble taking off and apart unless I start having problems again). I did a 60 mile drive with a few stops today and no problems. We'll see how it goes.
 

·
Registered
Joined
·
228 Posts
Discussion Starter · #17 ·
Had another incident where the two symptoms appeared again: Drove about 20 miles, stopped, did an erand, got back in the car, drove off and the third gear shifted hard again (clunks into gear). Stopped, did some shopping, got in, drove off, thrid gear was fine. Another stop, did some shopping, got in the car, drove, off, wouldn't engage 2nd gear getting on the freeway, so I threw it into Neutral then back into Drive and sure enough it was fine again.

Starting to sound like what the transmission guy is calling the "Neutral switch" and you are calling the "Range Mode Switch"? But the transmission mechanic wants to see it happen a couple more times before he's convinced. The pattern isn't real clear yet. I'll go along with that because then I'll know better if it's really been fixed too.
 

·
Registered
Joined
·
1,043 Posts
keen to get the answer for this, as this is EXACTLY what my 4L30e does on my 98 3.5
 

·
Registered
Joined
·
228 Posts
Discussion Starter · #19 ·
Chikoroll, you are going to have to be patient because it hasn't done it since that time, and I've been driving every day. Go figure.
So in the meantime, if *you* get an answer, let us know! :)
How consistent is your problem? If it happens a lot, you'd be in a better position to try replacing (or reconditioning) the Range Mode Switch and seeing what happens.
 

·
Registered
Joined
·
228 Posts
Discussion Starter · #20 ·
Well it did it again. I was pulling out of a parking lot, and it would not engage the next gear until, while still moving, I moved the shift lever to N then back to D. Same getting on the freeway.
So when I get back from the desert I'll want to look at replacing the Neutral Safety Switch (some here have called it the "Range Mode Switch").

I went ahead and ordered the Neutral Safety Switch from Autozone (http://goo.gl/bn0f1). I'll have the transmission mechanic put it in (he said he'd charge $50).

Let's hope it helps!
 
1 - 20 of 21 Posts
Top