1998 Isuzu Trooper won't shift into 3rd.

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1998 Isuzu Trooper won't shift into 3rd.

Postby tsuchida » Mon Nov 24, 2008 7:57 am

I have a 1998 Trooper that will no longer shift into 3rd gear. Beforehand, I had the dreaded range mode switch issue so I removed the old one, cleaned it out, put in new dielectric grease and had the Isuzu dealer flush the auto transmission fluid just to be safe. There have been no leaks and everything was fine and shifting like new for well over two months until out of the blue it started the hard shifting again, just like the last time. This time the new behavior was the transmission light flashed ONCE and never came back on. It was at this time that it developed the shifting problem and wouldn't go into 3rd gear. I thought "oh great, it's the range mode switch again". This time, I replaced the range mode switch with a new one from the Isuzu dealer, while under the truck I observed no leaking liquid from the trans or engine (no oil spots under car or on the chassis). I read about a "limp" or "safe" mode the trani can go into but I also read you should still be able to shift manually. I tried it and while I can get it to shift down into 1st, I cannot get it shift into 3rd gear. The best way to describe the behavior is to say that someone opened up my transmission, removed 3rd gear and up, and put it back together. The modes on the shifter, light up as expected (P, R, N, D, 3, 2, L) (might have the order wrong, but you get the idea) and they don't jump around. Drives in reverse and D just fine as long as you don't expect to hit any gear above 2nd. Again, it simply won't shift into 3rd or higher, the engine just revs. No smokey smells, no weird noises, no grinding, no hesitation. It's like someone just removed gears 3rd and higher. Well, I hope this gives you enough information. Oh, I also reset the ECM by removing the 30A fuse for ~5 min while I checked all the fuses to make sure none were burned out (all were fine). I'm handy with cars but transmissions are beyond my meager skills.

Just last night I had an idea and tried to engage "Winter Mode". I was wondering if the Trooper transmission would engage 3rd gear like it is supposed to. It did not. It affectively went into neutral. I'm not saying it shifted into neutral, I'm saying it didn't shift into 3rd gear and revving the engine didn't result in any torque applied to the wheels. I know it would take a bit more torque to spin the wheels from 0MPH if you started in 3rd ger, but I revved to ~2k RPM and the Trooper didn't budge.

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Re: 1998 Isuzu Trooper won't shift into 3rd.

Postby Dae » Mon Nov 24, 2008 8:15 am

tsuchida wrote:had the Isuzu dealer flush the auto transmission fluid just to be safe.

Sorry to say it. But this may have killed it. My first transmission died after the dealer "flushed it".
I wouldnt have got that thing flushed, with that much mileage on it.

I think the least you could do is start the truck up for 3 minutes, then pull the transmissions "fill plug", make sure the fluid just dribbles out a little.
Look at the color of the fluid, best to use a napkin. If it has a burnt smell to it, the transmission could be toast.
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Postby SurferJoe » Sat Nov 29, 2008 1:34 pm

If it were me, I'd pull the valve body out and bench it for a stuck valve.

When you flush a transmission, you just break up the junk that is stuck in the outer periphery of the converter that has collected debris and metal flakes and clutch fibers into the outer area from centrifugal forces.

The junk will stay there until dislodged by the flush and then they float around, looking for something to jam up and contaminate/lock into non-actuation.

Flushing a trans is suicide.

I'd check the valve body ASAP and stop driving it and trying to make it work — you'll mess it up if you persist and then need an overhaul.

When will people learn to only go to the dealer for buying a new car and stay away from those idiots all- and any other times?

They don't care if they can fix or destroy your vehicles. Then can always sell you a new one.
Last edited by SurferJoe on Sun Nov 30, 2008 7:09 pm, edited 1 time in total.
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Postby timrkopi » Sun Nov 30, 2008 2:26 pm

Lets say it was not the flush. What else could it be?

Most trans flushes I see advertised just get more fluid out than a
regular "pan drop". Some do not even use a machine. They just take
the lines off by the radiator and add as it spills out the line.

Do you change the trans filter?? What did it look like if you did.

I would not worry to much if it is not slipping. Did you check the trans
electronic connections?
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Postby SurferJoe » Sun Nov 30, 2008 7:08 pm

Here's a rule in transmissions:


If it won't shift when it's SUPPOSED TO, then how in the world can it be right?

I would not worry to (sic) much if it is not slipping.
is so-o-o-o wrong on all fronts. It WILL bite someone in the short hairs sooner or later. I don't care if it's low fluid, no fluid, bad fluid, bad filter or your grandmother's experiences in 1808 in her Conestoga wagon, WHEN AND HOW is totally important to a transmission.

If you don't have gauges to test the line pressure and the apply and/or shift pressures and cannot make heads or tails outta the WHY it acts so, and it just had a flush and/or service, then go back a step and try to figger out what went wrong. It's very human to try to place blame on something that you don't understand, but regroup and try to get hold of the reason(s) why this "something" happened.

Transmission "flushes" are a joke and usually cause more troubles than they solve. Most people get them done when the problem has shown itself, and hoping that a good flush will cure it, they don't understand that a flush or service ......(where the filter actually gets changed and the magnet gets investigated for steel shavings and the pan gets perused for debris and burned clutch material and things that do NOT collect on an uninvented aluminum magnet get looked at and diagnosed) — .......is only a maintenance procedure AND SHOULD NOT BE DONE hoping for divine intervention or sprinkling chicken bones on the problem to make it all go away.

Any malfunction must be diagnosed and/or repaired or if you are cognizant of what the reasons are for the strange behavior, then you can choose to ignore OR fix it.

Some times I choose to iggy the problem, 'cause I know the ramifications for doing that and driving it anyway. After all, I can fix my own.

Other people may or may not know what the situation calls for and they drive the thing into a cinder of smoking metal and rubber whilst others somehow get away with it for the rest of their natural lives. Search me how that happens!

What has been described here and the sequence of events leading up to the posted malfunction indicates (to me) that this is a contaminated control problem. So much better if it isn't, but if it is, just driving it and trying to force a mechanical device with no mind of it's own to work correctly is just wishful thinking.

It would be a waste of this site to fall back on the guy who has questions and tell him to "Go to a professional shop and get it diagnosed correctly" when what we are trying to do is offer some hope and a modicum of sober (yet witty) help and proffer the sum-product of our experiences.

I like to sit around the fireplace with a beer in one hand and a keyboard in the other telling war stories and how we (all) accidentally burned one or two cars down to the hubcaps by our mistakes, but we are really attempting to help here. Yes, Virginia, I have some car skeletons in my closet from days of yore, but that was then and this is now.
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