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4L30e Transmission Shifting Problem - with Solution

222K views 94 replies 53 participants last post by  rbral 
#1 ·
Hello folks,

New to the board and am looking for some tech help. I researched this issue on the boards already, but there are conflicting replies.

I have a '99 Isuzu Trooper auto. Coincidentally after having my transmission fluid exchanged at a local establishment, my transmission started shifting very harshly on the 2>3 shift, both up and down. It slams into gear so hard that the drivetrain resonates like a ringing bell. It only seems to do this after the car has sat for a day or so and is used in the morning.

Oddly, this problem will correct itself immediately if, upon realizing the problem, I pull over, shift the tranny into Park, and turn the ignition off. I wait 5-10 seconds, restart the vehicle, and everything shifts fine. I have not yet had trouble correcting the problem using this method.

In reading the board, it seems that some possibilities are the 2>3 shift solenoid and the TCM. I would appreciate some guesses on what the problem is and suggested repairs. Can the solenoid be replaced with the transmission still bolted in, or must it be removed? Can the solenoid(s) be tested in some manner without removal?

I would appreciate any theories. I have a pretty good base of mechanical knowledge, and would be performing any repairs myself short of a total trans rebuild. Thanks for your time.

Regards,
Tom
 
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#2 ·
First off, make sure they have the ATF level correct. Many places unfamiliar with the (dipstickless) 4L30E dont do this right. Second common cause for harsh shifts is a faulty range/mode sensor (attached to the shift arm). Amigo2K was recently having tranny troubles and it turned out being a bad intake manifold gasket!- so misfires will also throw the tranny into limp mode causing harsh shifts or constant locking/unlocking of the torque converter. Higher end computer diagnostic tools (code readers) may be needed. Good news is- it *rarely* is not the transmission itself.
G/luck
Joel
 
#3 ·
I could be this too:

faulty range sensor?
I've had a problem with hard shifting on-and-off for over a year. It usually happens only in the morning, and is always after the dash light fails to indicate that the truck is in drive. I had the codes read at a dealer last June, and got back a P0705 code. Is this the range sensor malfunction? If so, any recommendations on what needs to be done and where to get it looked at?

I had the same problem with my 99 Passport. I was able to remove my range sensor, take it apart and clean the contacts inside. I remember it was quite dirty and greasy inside. I think they used too much dielectric grease in it, but the contacts were definitely dirty so I cleaned them reassembled it and I have never had the problem come back. The unit is located on the side of the transmission (drivers side) just forward of center. It's been well over a year since I fixed it, but if I remember right to remove it there was a small metal shield that pops off. Then I had to remove 2 bolts and 1 nut that holds the shifter arm and unplug the wire harness (the wire harness was a little difficult to unplug due to the tight space) and the unit will just slide right out. You will need a torx driver to take apart the unit. I wiped most of the grease out of mine; I left some of the grease there so things will slide properly and to keep moisture out. Depending on how dirty the contacts are you can clean them with a pencil eraser or a very, very fine sand paper. Don't spend the 90+ dollars for a new one this is a fairly easy fix, once you see the inside you won't think it's worth the price tag! It should take you about 45-60 min to repair.
 
#4 ·
Folks - thanks for all of the replies. It was indeed the range sensor. That little sucker has a seal that really doesn't seal all that well. I took it apart, hosed it out with contact cleaner, regreased it with dielectric grease, and reinstalled it.

You can tell this is happening to you when you shift and the gear indicator lights in the dash flash everywhere. This morning, I shifted into drive and the "L" light came on.

Anyway, thanks again. That's a load off my mind and a strain off the drive train.

Regards,
Tom
 
#5 ·
Thanks Serranot

I'm having the same exact problems on my 99 Trooper tranny.
It's been a little frustrating , but it also happened when I swapped
out the tarnny fluid, I have not done a full fill and flush but I am planning
to use the ATF COOLING lines as posted , i.e. let the tranny do the pumping and I use my hand pump to do the filling.

I really hate this fill plug idea from Isuzu , another reason why people don't like them and they may be leaving the US market.
 
#6 ·
With my 2000 Trooper and just over 64,000 miles, I have gone through the task of tranny fluid exchange twice now. The first time, I was having similar tranny "irregularities" (shifting problems with intermittent gear indications) and thought the tranny fluid exchange might help, but it didn't. What I eventually found was a very sensitive position sensor... anytime I put the Trooper in a bind, such as backing up my trailer, or parkiing on a steep hill, I could count on the flashing gear indicator (randomly moving between gear indications) and hard shifting. Once I moved to a normal flat surface, I would park the car, hold the brake, travel through the gears, and then shut it down, letting it sit for 5 to 10 seconds, and restart. The position sensor seemed to correct itself. The second time I swapped the fluid, I did it primarily to go to a better grade fluid (Amsoil) while also installing a transmission cooler. There is no easy way to do this fluid exchange. I have used both a hand pump and the syphon method (fluid sitting higher than the tranny), but anytime you are pumping fluid upward to fill something and waiting for the fluid overflow to tell you when you have completely filled the sump, you have to wonder what the tranny designers were thinking (or drinking or smoking).
 
#7 ·
I have had the same issue with my '99 Trooper. I will definitely try the range sensor fix. It definitely seems to revolve around cold weather as I live in Virginia and the problem has just started occuring again in recent weeks. When it went over the summer I had some suspicions that the thermostat was stuck open as the 4L30E won't shift properly until it warms up. Of course in the summer time that is not an issue where I live. Again, I will try the Range Sensor repair as it sounds exactly like my problem. Other than that my Trooper rocks!

FYI, the 4L30E is actually a very universal transmissions used on all kinds of vehicles. Even Beamers!!
 
#8 ·
In response to the "its not usually the transmission", I quote from the customer copy of my latest dealer invoice "Failed trans internally Code P1870 major clutch material in pan". It was the 4L30E transmission in my 2000 Trooper.
 
#10 ·
Tom,

I have the exact same problem with my 2000 trooper 4x4. I want to try cleaning the range sensor as you described. Where is the sensor located and how hard is it to do yourself. i am npt a mechanic but i can do some moderate repairs.

Thanks
Jason
 
#11 ·
Jasestrong said:
Tom,

I have the exact same problem with my 2000 trooper 4x4. I want to try cleaning the range sensor as you described. Where is the sensor located and how hard is it to do yourself. i am npt a mechanic but i can do some moderate repairs.

Thanks
Jason
The photos below were taken from under the driver's door. The job itself is not all that complicated, but disconnecting the wiring harness and such can be a challenge. It took me about an hour to do the job. Instructions for doing the job are contained in this thread.

Tom





 
#13 ·
I guess I am the latest Isuzu owner to what seems to be the same problem, but let me say first this is a great site and that I really appreciate the time and effort that many of you put into helping others.

And now: Does anybody have a picture to help me recognize the sensor on the tranny? I looked aaaat the tranny under the passenger's side, but I did not see anything. I was not sure what I was looking for either.

Thanks is advance.
2000RLS
 
#17 ·
I thought I was having ABS problems on my Amigo, since the vehicle only started acting up when stopping. It jerked and bucked really bad. I pulled the ABS fuse, and it still jerked and bucked all over when stopping.

I found the FAQ about the range sensor, and sure enough, my PRND321 was off. I think it was just having trouble deciding what gear to downshift to.

When I cleaned the sensor, I did not unplug it. There was plenty of room to let it hang, take it apart and clean. The contacts were filthy. I used contact cleaner and regreased with dielectric grease.

Put the ABS fuse back in, and a few thousand miles later it still shifts and stops with no problems.
 
#18 ·
Any one have a picture of this selector apart? I've taken it off and well in the time i had to look at it.. it sure couldnt get it unhooked! so i put it back ..
If i leave it hooked up.. is there springs.. small piece.. etc.. that I possible will break my neck trying to figure out how to put them back in... Right now.. my reverse is a lil outta place but.. the light still lights up IF u have the right touch.. but D doesnt.. n..3..2.. 1.. light up fine.. the truck consistanly shift at high rpm's and will not .. "freewheel" when goin down a hill or even shift to the next gear unless ur over 3000 rpms.. Im trying to figure out if THIS is my problem or is it my tranny?... any suggestions?... any pics?...

Thanks,

Kevin
 
#19 ·
It's your problem. The gunk in that thing screws up the transmission's behavior big time.

There isn't much in there, just some sliding electrical contacts. If you go slow, you shouldn't have any problem putting it back together.

Regards,
Tom
 
#20 ·
I wished I found this site a month ago when my trooper started this problem and I could have had it fixed the 1st time. I have a 2001 trooper 2WD that last night, the tranny stopped working all together. 1st, there was a tranny leak and it took me 3 times and 2 weeks to get that under control, but still wanted to leak. After the 1st time, it ran fine and I replaced the tran pan seal and filter(good thing cause the fliud was more of a gray colour then red). Filled it up with new cherry juice and ran good for 2 days, then started the same problem and started to leak.

I need help to see where to go from here and is there a way can be mod to have a dipstick?
 
#22 ·
I don't have any photos, but what too look for I do have an idea. 1st, take your time taking it apart. the 7 long bolts in the bell housing that holds the 3 sections together are 1/2 inch 6 point. If you try the 12 point, you will strip the bolts. I bought the rebuilt kit and I only needed about 3 things in it. Now putting it back together, it is a pain and takes a while. you need to make sure eeverything lines up right.
 
#23 ·
Riddle me this...

I attempted to remove and clean the range sensor/selector yesterday. I got bored, and decided to give it a shot in an effort to clean up the transmission's shifting.

Got as far as removing the shift linkage, and taking the bolts out that held the range selector to the transmission casing...

However, when it came to disconnecting the connector that connects to it, I found none. Anyone else attempted the same on an early-model 2nd gen Trooper? My connections were all hardwired. :?
 
#25 ·
I performed this cleaning and re-greasing with no problems thanks to this thread, but when I put it all back together my shifter will only go into P and R. Disconnecting the shifter from the range/mode sensor, I can manually change the gears on the tranny, but not on the shifter inside the car (other than P and R as I mentioned). Has anyone had this problem? Is it possible the cable is caught somewhere that I can't see?
 
#26 ·
Hello there,
I'm having similar shifting issues with my '02 Trooper with 78k miles. It seems that my problems are occuring mainly during Downshifting.

I've clicked on the link for the "How To" PDF file but it seems to be a dead link.

I would appreciate any assistance!!
 
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