I originally had trouble with this trooper about a year ago, where it started to occasionally slip out of gear while cornering then back again when the RPM's dropped. Got progressively worse over a few months and then finally lost all forward gears, but reverse worked fine. Put it aside in my warehouse in disgust until I had time to deal with it, and so recently I did a filter and fluid change on the trans with the hopes that would help, but it did nothing. Still no engagement in gear from a dead stop. I did discover, by accident, that the car would drive fine in "winter" mode when the button was pushed, and then once you got up to speed on the road (2nd gear and up?) then winter mode turns off and the car continues to drive perfectly normal- downshifting and upshifting perfectly, until you come to an almost dead stop, at which point I have to press the 'winter' button again to engage 1st gear. Reverse still works great no matter what. Any ideas as to what is going on here? Sounds like an electrical problem, and I'm a competent wrencher, but where do I begin to sort this out?

 

I have the exact same problem with my 99 trooper. please let me know if you resolved it. thanks

 

Well, resolved in the sense that a local transmission shop confirmed that 1st gear is totally gone. I bought a used transmission to put in, but I'm not yet convinced it's the right one. So- if you hook your car up to a code reader and it's not flashing any transmission errors, you're looking at a rebuild.

 

"winter" mode bypasses 1st gear and uses 2nd gear to start out.

All auto trans failures I've seen, even on Isuzu', have all been oil related from a lack of maintenance. typically in the 135-175K mile range, well before the engine.

A better oil will surely help keep those auto trans happy.

 

I totally agree with Gary - in my case the PO of my trooper had disconnected the radiator, loosing fluid that wasn't ever topped off again. Driving it with low fluid level killed first gear.

 

I should've also mentioned that the gears can manually be selected with the shifter. Makes it easy to tell which gear(s) are having problems.

It also helps separate out the computer, as manual selection bypasses it to directly activate the shift selenoids. This is a "fail safe" mode on most auto trans. It's a neat trick that most auto techs use for basic diagnosis, in addition to any dash lights and codes that are present.

Specific to the Isuzu's: there are a couple of main harness plugs between the firewall and trans, on the left side (drivers), easy to find as they are large, among smaller connectors at the trans. They are prone to contamination and corrosion. This will cause Voltage and Resistance values to be out of spec. Normally one can test the whole system at the TCM/computer but it requires a wiring diagram and specs for each component, plus a trouble tree that outlines the process sure helps.

With that said, these steps are usually taken after it's "too late" and the trans has major problems. Or that the computer indicates a problem that requires fixing any wiring problems after replacing the "bad" part. This could be a temp sensor that relies on R values to calculate temp but could be effected by excessive resistance in the wiring. This will cause a mis-reading.

Vehicles that are from the "salt belt" or often power washed are likely to have wiring problems, too.

Low fluid, whether in a trans or anything, can and will cause premature wear and damage. Keep in mind that Wear and Damage are the same thing, but Wear is to a lesser degree, as Damage is an advanced stage-- that is unless there is a sudden Mechanical failure (which still tends to be oil related most of the time).

I can say with authority that very, very, very few people correctly maintain their vehicles. Even following the OE specs is often inadequate, as each vehicle is used differently. OEM's don't want to be the one that requires "over servicing" compared to industry standards. They want the vehicle to make it out of warranty, hopefully a longer to create Brand Goodwill. If a product lasts too long the company loses $; it's a balance, one that doesn't side with us very well.

Most people operate their cars in a "Severe Service" maintenance category, but don't know it. Most shops will not try to educate them, either, or the Service Advisor hasn't a clue, or doesn't want to create a potential conflict. Plus, they will always make more $$$$ replacing major components than changing engine, trans, and driveline oils.

Probably the biggest benefit of newer vehicles is that the OEM's are using better oils to make them last longer (mostly to advertise a better warranty). Some Trucks have synthetic r.diff oil, I noticed since about 2000. Cars like Audi and BMW have for many years used synthetic oils, even in the power steering systems. It sure helps, but still needs occasional servicing.

Ultimately the consumer is left to fend for themselves, however the owners manual does outline what Severe Service is, but it's insignificant that few see it (usually a small part on a page), or pay head. No one wants to pay more than needed, so it's ignored- then things fail and the vehicle is often condemned as being "bad", etc.

I'm digressing somewhat and will call it quits for now. Hope this was interesting.

 

very interesting, thank you. So winter mode takes off in 2nd or 3rd? Seems like mine may be 3rd. Because when I downshift after getting up to speed in winter mode, I can downshift to 3 and it still pulls. Anything below that (2-1) and nothing.

 

It should start out in 2nd gear; check the owners manual for more info.

Starting in 3rd is also common for a trans that has ruined the lower gear clutch packs. The planetary gearset can't lock and unlock as needed to alter gear ratios. Normally reverse gear will still work.

Once up to speed 4th gear is engaged, which would allow a shift to 3rd. Try shifting to 2nd gear, or starting in manual 1st gear, the engine might rev a lot. It might develop enough hydraulic pressure to provide minimal clutch holding. Worked on a Rodeo that at near redline would somewhat move in 1st/2nd. This helped diag. the problem, but appeared abusive to the shop customers. We drive the crap out of cars but it's not for fun (okay my tech friends that work on Ferrari's/Porsche's and REAL race cars, that's different!). One in a 1,000 street car is fun- like a customer's Honda S2000 (a college professor) that said go have fun with it, that had nothing to do with the work I did to it.

Moving on:
To verify visible damage, remove the oil pan. Will probably find a lot of clutch material and some metal, if so it's time for Plan B. For the mentioned vehicle, it was replaced with a used unit to save costs.

Pointing out the obvious, but it's important to do a full trans service on the "new" trans. I always recommend a shortened 2nd service interval of 1 year or 12K miles on a "good" used trans. If the old fluid was very used, burnt, or the pan had major debris, then would elect to use another trans instead. Most suppliers will only provide a short warranty only if all services are done. They are also delivered 'dry' w/o oil. This is good as you can't drive anywhere. This requires fresh fluid, if nothing else is done.

If there's no choice (using a so-so used trans), then a full service (100% fluid flush & filter change) should be done, then "drain & fill" every 3 months for a year (only changes 20-40% of fluid). Fancy oil can be used after the trans is flushed out. Expect to use A LOT of oil. Most trans flush machines will use about 20 qts, not counting the 4-6 used to prime the trans when the filter is changed. However once driven residual contamination will be agitated. It's a high-needs situation for awhile.

The torque converter seal should be replaced prior to installation. Also a good idea to replace the engine rear main seal even if it's not leaking at the same time. The flexplates are prone to breaking. I'd replace it with a OE new piece, or low mileage used. The bolts must be torqued to spec otherwise can/will crack the flexplate, but the chances are much better with a new flexplate. Experience speaks.

Keep in mind these are GM transmissions (4L60 i think), not German or Japanese, and don't tolerate abuse as well.

Not doing any of these steps can and will cost a lot more (insert your favorite saying here) later. Any shop that contradicts the core points presented, probably needs more experience, or needs to be more honest.

Not to finger point, but a failing transmission is usually just the start. I've yet to see a situation where ONLY the trans was neglected-- this means everything else that uses oil or fluid is usually not far behind. Sometimes mechanical, like an overdue Timing Belt job.

A good shop/mechanic might even have a heart to heart before taking your money. Expect to spend several hundred or more to bring the vehicle to a reliable condition. This means changing ALL the fluids, yes, power steering, brake fluid and coolant too.

The most common argument is that "it's not worth it". Why spend $1000-2000 on a vehicle worth $500 with a bad trans? A $2500 car, even $10,000 used car will need work. Figure $500 just to get it "okay" for reliable and continued service. Those that are unlucky repeat the viscious cycle and either deal with continual problems or excessive "repair" costs.

Fact is any car more than about 5 years old is coming due for major services. Buy a new car? When it's finally paid for it'll be due for $1,000 or more in work at the shop, right when everyone is glad the payments are over. Some work is necessary, some preventative. Whatever isn't done, will cost more later. By 7-10 years, anything can and will go "wrong".

With reasonable maintenance, a top quality oil, one should feel secure they'll unlikely never have a mechanical break down. Put $50 a month aside and that'll usually cover the basics for non specialty type vehicles.

 

check out '4L30 transmission band adjustment' on youtube, it solved this exact same issue i had on 02 isuzu rodeo