Hey guys I have tried searching the threads here and I do see that it is fairly common for electrical/sensor issues to cause trans shifting issues.Ours starting acting up recently first shifting hard into 2nd and 3rd and then not shifting into 2nd and 3rd at all unless the RPM's were really low.The truck was dropped at a local Aamco who of course told me I needed a total rebuild for anywhere from $2500-3500.
Well I jumped in the truck tonight after reading a thread that made perfect sense which said to manually shift the trans through 1-3 and then into drive.If all of the gears grab then hard to believe the trans is totally shot.Well sure enough the trans shifts just fine with manual intervention.Then a funny thing happened and I drove around the neighborhood and up and down a bunch of hills and the trans shifted with no intervention.Not the smoothest shifts ever but the truck worked.Again hard to believe the trans is totally shot.When the problem fist started it got progressively worse the second day and that is when we towed it to the shop.Now the truck has been sitting for a week and a half and it's suddenly "normal".
So the question is does anyone have any more specific info on how to diagnose this or am I at the mercy of finding a shop/dealer that will actually fix the problem rather than just saying "you need a complete rebuild".
Does anyone have/know where to get good manuals or can anyone recommend a good shop in the Raleigh,NC area?
Thanks,Vic

 

well I was surely hoping the answer would have been here. the exact same thing is happening to my daughters 2000

 

Interesting shift behaviour. By 2001 almost all transmissions used electronic control of shift points. That manually shifting it made it straighten up and fly right makes me consider some preventative maintenance.

The electronic system controls the solenoids. In most cases an automatic transmission held in manual low will run higher pressures, and apply bands for towing application. Break away, on the other hand, does not place the same pressure from the front pump that manual low puts to the system.

Many japanese transmissions are systems that are akin to the Ford or Mopar transmission designs. Some will emulate some GM designs. So far I haven't encountered any unique systems from the orient, but that doesn't rule it out.

These are going to have a transmission filter that will need attention, and a fluid change interval.

Have you had the filter and fluid changed? This is something I would do myself, but I don't know your circumstances. Generally, if you change the filter and fluid every couple of years, your golden. If not, then, like most folks that drive till there is a problem, you may have troubles.

If it's acting right, change the filter and have the sytem flushed and fresh fluid put in. It's the least expensive fix you have at your disposal.

What the automatic transmission people want you to believe is that these transmissions are complicated. They aren't. Electronic controlled ones are less hassle than the old mechanical ones. The computer just decides when to shift. That's a lot harder with shims, springs, and governer weights. You don't have to worry about all that. The computer does it for you. Solenoids are binary devices. They get fired to cause events.
If the sytem is loaded up with a bunch of guck from being ignored for xx years, it's not going to work right.

Change the filter, change the fluid. See if it behaves itself after that.

2¢

CJ

 

Well thanks a lot for the 2 cents.I've been to 2 tranny shops who both say a rebuild is needed at a minimum of 2500 bux.That isn't going to happen.Funny thing is that the problems started after a "flush and fill" by one of the local lube shops.I wish I had left the thing alone.The problem may actually be mechanical because when the truck sits for awhile it behaves fine and as the truck heats up things get progressively worse.Tranny guy said that has to do with clutches inside the tranny that need to be replaced.I don't know enough about trannies to know if that is BS or not but 2 different guys have given me the same story so I may be screwed.I can try what you are talking about but I really don't want to dump any more money into this thing.Wish I never bought it.I read 10 million reviews about how great and reliable they are and this thing has been a money pit.No more Isuzus for me.
thanks for the response.

 

How mechanically inclined are you?

http://info.rockauto.com/PartsAuthor.../MRK5400F.html

CJ

 

Been thinking about this some more.

When the heat comes up, your dropping line pressure. This could very well be frictions. It could also be a simple line pressure adjustment.

That kit I linked is $174, and includes pretty much everything. You can get a master rebuild kit from your FAPS. (Favorite Auto Parts Store.)
I don't have an Isuzu automatic, but I'd lay odds it's a metric GM design. Not too spooky to go through. The hard part is getting it clean enough. So clean, Howard Hughs would eat off of it before you take it apart. Clean. I don't crack a bolt till I've scrubbed for half a day.
Getting it out of the rig is the hard part. (Physically and technically.)

If you've got a place to work, and something to drive, consider doing it. Takes time, not money.

Just in case I didn't emphasize enough, get it clean. That effort will pay off tremendously. Anyone that knows how to disassemble and assemble an engine properly can rebuild an automatic transmission. There just aren't that many parts.
Snag an FSM or a transmission specific manual. Don't bother with aftermarket motors manuals unless you need something to light the wood stove or block the shop door open for ventilation.

CJ

 

Well thanks a lot Ceej.I appreciate it.I am pretty handy and I've done some motor work but not in a long time.I'll definitely consider it.
Any idea how to adjust line pressure?

 

Your going to need an FSM for your specific vehicle, or a transmission specific manual. Chances are, if the line pressure is too low, your frictions and steels will need to be replaced anyway. Might buy you some time though.
Line pressure is adjusted by a mechanical clearance on the valve body, or is controlled electronically with the Control Module based on a transducer. Your tranny is a lot newer than the ones I frequent, so it could be either.
Have to look around the internet to find out, or ask somebody friendly at a tranny shop. Sometimes they will share info.
From what you were saying, the transmission wasn't slipping, just shifting strangely. Some of the sensors for the transmission may be accessible, and replaceable externally. Others may be internal. The adjustment is accomplished on the valve body if it's mechanically regulated. That requires getting inside.
There may be ports for testing pressure on the case that can be accessed without taking the transmission apart. I do not know where they are located on your particular transmission.

CJ

 

Well thanks again Ceej.I wish you were in Raleigh-I would just pay you to fix this sucker.It may be more than I can bite off honestly.I don't have the tools and setup to do all this.Makes me wonder if replacing the trans control module is worth the effort.Those are external and cost about 200 bux from what I hear.Once the truck gets warm the truck struggles to shift and eventually won't shift at all if driven long enough.It gets progressively worse the more you drive which would seem to be mechanical.Not sure if a shift module could possibly remedy that.

 

If it's shift behaviour only with no slippage evident, I'd see if a wrecking yard had one for the right price and swap it out. $200 for a part you might not need is pricey.

Call a yard tomorrow and see if they have something appropriate.

CJ