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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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#77 ·
hello need help bad
have 2002 isuzu axiom 2wd transmission shifts good when cold no check engine light
after about 13 miles the engine light comes on code p0401 and transmission light.
starts shafting really hard next day light off start all over again
cant read code for transmission just put this transmission in
 
#78 ·
P0401 is EGR Flow Insufficient which is usually caused by blocked tube that runs from the EGR valve to the front of the intake manifold. This should not affect transmission operation.

Check to ensure that the gear select indicator lamps on the instrument panel match the position of the gear shift lever for all 7 positions.
 
#80 ·
Hard shifting is typically the result of high hydraulic pressure. The base pressure is controlled the transmission Pressure Control Solenoid (PCS) also called a Force Motor. The PCS is controlled by the transmission "computer" (PCM/TCM). If the Range Mode Switch(RMS) discussed in this thread is not working properly the PCM does not know what gear has been selected so it commands the PCS to increase pressure to maximum to prevent clutch slippage. The RMS also operates the gear indicator lamps so if they are working the RMS is not the problem. Is this a rebuilt, reman or junkyard replacement. There is a possibility you have the wrong transmission installed. A 02 Axiom uses a 4 valve hydraulic pump housing. Rodeo transmissions do not. The correct transmission should have a TAG ID of 96024169
 
#83 ·
If the ATF overtemp lamp is not illuminated the cooler is probably not plugged. Additionally, the discharge side of the cooler is used for transmission lubrication so if it is still operating it is probably receiving lubrication.

The Force Motor ("PCS") default state is wide open which results in maximum hydraulic pressure, maybe you have a defective Force Motor.
 
#85 ·
Hello, I need Help!!!

I have a Isuzu Rodeo that has a troubled Automatic Transmission :(

I Accelerate to about 20 miles a hr in 1st or 2nd and it wont go faster, the RPM's keep going up
and it feels like its in neutral until I drop to about 15 mph then it seems to go back in to gear.

Some times if I really stomp on the Gas and get my momentum going it will shift in to 3rd and go faster.

All lights on the Dash correspond to the shift selector, except for the "D" wont lite up.

And if I press the Winter Mode Button, the transmission disengages (feels like neutral).

I removed the Range Mode Selector, it's the Triangle shaped device on the drivers side of the trans and
cleaned it and re greased it and reinstalled it, but it still exhibits the exact same symptoms.

Any Ideas, fixes, or advice would be appreciated....

Thanks a Bunch!!!
 
#88 ·
My transmission down shifted really hard on the freeway when I was climbing steep grades. It was a real loud clunk. When I changed the ATF, I followed the factory manual and tested the fluid to the correct temperature with a Fluke IR Thermometer when I drained off the excess fluid. The problem was corrected! It seemed too easy.
 
#89 ·
Hi, I just move to Australia and bought a 2000 3.5 V6 Jackaroo. After few kilometres something strange happens on a highway, a hard "gearbox" stride, some alarm lights on the panel flash and the gearbox, (all the gears), were slipping. After few kilometers, needed to poll over and restart the engine, suddenly the problem got solved. Next morning toke the car to a Gearbox mechanic, put the scanner and some "faulty solenoid codes" appears. His diagnostic was to change the solenoid. Few days later and AUD 640 dollars poor get my car back, with the advise that if its start doing crazy things I'll need to to wait him come back from his 15 days vacation. Next morning after push the gas on an avenue, the same lights flashing on the panel for few seconds, then gears slipping..., this time I knew that after restart the problem will be solved. I keep like this for few days, if I draw like my grandma everything was Ok, when I push the gas hard the same problem start, till next engine restart. I start read the forum's till I got here, after read all your experience realize that it was something on the electronic, if not the problem will keep forever. Then I start thinking about the difference when I push the gas hard, and one day when I push the gas looking at the panel I saw the voltage indicator going till 18 volts..., that's was my problem from the beginning !!!. The voltage regulator of the alternator were unable to control the voltage when I push the gas hard, and with 18 volts for few seconds all the electronic of the car went crazy.
After change the alternator my self, all the problems were solved.
Thanks all for the comments, helps to analyze my problem. Thanks to the forum, for sure it'll help me in the future.
Regards, Pablo.
 
#90 ·
Hi, I am new to this forum, i have a Isuzu Bighorn 3.1 diesel automatic transmission, I encountered this problem just a week ago when i start the car to let the engine heat up for about 3 minutes i smelled something its like burned clutch something like that. Then when i put to drive suddenly it wont run even if i step on the gas on high rpm but when i shift to reverse it runs normal? i just change the atf 3 months ago, i went down to check if there's a leak on the transmission but its all clean, i'm wondering if this is a transmission solenoid problem?

I need your expert opinion on this guys before bringing it to a mechanic.

Thanks
 
#91 ·
Just wanted to say thanks for this thread and all the great info......

Here is a before and after of the range sensor off the better half's 01 Trooper.....

Had it off anyways for other things, and glad I spent the time to clean it up... seems the sensor vent hose has been off for a long time and the jiggle vent plugged solid....

I have cleaned a ton of the range sensors off AW-4s in Jeeps for no crank in park or neutral, but none have looked quite this bad..... and honestly the trans shifts alot better, never had a trans light or cel concerning trans stuff unless it was my fault for accidentally unplugging stuff. :D

 
#93 ·
alabamaoverland said:
Is a shift sensor and a range sensor the same thing? I am getting the same slamming in to gear and then the "check trans" light comes on. I restarted the trooper, and everything was better. The check engine light is saying shift sensor B is failing.
Shift B is the common name for the 2-3 Shift Solenoid. The component discussed in this thread is the transmission Range Mode Switch (RMS), sometimes incorrectly referred to the Range Sensor.
 
#94 ·
Has anyone heard of the transmission shifting down when going downhill? Mine does when I let off the gas going down a hill, like hill decent control. I just replaced my 2>3 shift solenoid and it made my rough shift not nearly as bad. I am wondering if cleaning the range mode switch will help even more. I was told it had the transmission rebuilt about less than 10,000 miles ago. I cannot find the PDF on how to clean the RMS. Any help?
 
#95 ·
My 2002 trooper down shifts when going down hill, with foot off the gas, above a certain speed, etc. to allow better engine braking. I dont know what other model years had it.
There are instructions on cleaning the range mode switch on this sight if you do a search. Here is one thread....
http://forum.planetisuzoo.com/viewtopic.php?f=4&t=98337

I am getting ready to do mine for preventive maintenance.

Good Luck!

Bob
 
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