Banging gears again!!! What now!

[jasonm621]

Note: longer that necessary story ahead: if you would like to get straight to the questions id like answered scroll to the bottom...
So about two years ago i had my transmission mode switch flake out due to the shift selector seal failing. Long story short is that the PCM had put the transmission in a "backup / limp mode" since the mode switch was flaking out. What the mechanic told me is that the "backup / limp mode" will shift the transmission with maximum pressure to prevent damage to the clutches, thus producing a gut cringing shift. Anyway It was a huge expensive nightmare and i never want to go through that feeling again.... I haven't had a single problem with the transmission until two days ago...
On my to do list this weekend was to change the transmission fluid as ive done every January since the incident. I was experiencing a hard clunk 2nd -3rd and 3rd-2nd shift every time. I got the car home with the reoccurring gut wrenching feeling that something is broken and got right to the forums. I found a ton of information, unfortunately i read it could be anything from a blown fuse to requiring a rebuild... Unfortunatly there isnt a way to pull any DTC codes from the PCM like you can with ABS, airbags and TOD... OR IS THERE???? From what I know you need a tech2 scanner (page 7A1-14 In the workshop manual) which runs around $500+

Frustrated i went to the garage, checked for fuses and shorts and changed the tranny fluid as i told myself i would. Since I cant read codes anyway, i unplugged the battery thinking that if some code is stored from the transmission unplugging the battery will at least get rid of the DTC and the harsh shifting will go away, but for how long.... Well technically to my suspicion it did work. After the fluid was changed i took it out for a spin and it shifted to be what seemed normal or even better than usual, no clunk anywhere. So for now Im keeping a close eye on it and hoping that the crappy shifts never come back, which im sure is high hopes...

Questions:
1. Has anyone had similar issues with 2nd to 3rd shifting? Apparently in the mechanical/hydraulic diagnosis symptoms index (page 7A-13 in workshop manual) there is no harsh 2-3 shift symptom they show in any of the charts???
2. Is there a way to check stored transmission codes without using the tech 2 scanner??? A way similar to checking the ABS, Airbag and TOD codes by jumping ports on the OBD plug...

Any help/input is greatly appreciated! Not just for me but for others having similar problems now or in the future.

[Lfen]

Yes, in my case I realized that these transmissions are real sensitive to fluid level, up or down just a little and you will have problems. In my case I was down 1/2 quart and got the hard downshifts. Once I rechecked the fluid the right way and added the 1/2 quart. Problem fixed. So before you do anything else, I would recheck fluid level.

[jasonm621]

Fluid level seemed to be normal. I let the car cool for the day, started it up again, went through the gears and crawled under to open the fill hole. Sure enough fluid was drizzling out so i know the level wasn't low... When i changed the fluid it didnt seem to be that deteriorated either. The fluid wasnt clouded and still had just a bit of color in it like a black cherry...

[Lfen]

Did you check while engine was running ? This was the mistake I made. I checked when engine was off. Huge difference

[jasonm621]

Did you check while engine was running ? This was the mistake I made. I checked when engine was off. Huge difference
Engine was running and fluid was warm when i checked it and filled it up. I have no reason to believe that the fluid was low at the time of the bad shifts...
I was also careful to measure how much drained and how much i put in. The volume was near identical (+or- 150-200ml)
First time I did a transmission change i filled the transmission up while the engine was running then shut the engine off to put the plug in. HUGE MESS on the garage floor! I'll never make that mistake again... Why did GM make the 4L30E so difficult to fill and check the level?!?:mady:

[Lfen]

Good question. For me if the Fluid didn't work I was just going to change all 5 solenoids out and hope for the best. Found the 5 solenoid kits on ebay from $150-$300. If that didn't work, I figured rebuild time. Good luck and keep us updated

[LittleBeast]

I had my transmission rebuilt back in 2008 and it seems like I might need another rebuild. A couple of questions:

1) what is the theory behind replacing the solenoids first to see if that fixes things?
2) which solenoid kit should I get the one for 1990-1999 Isuzu's, or 2000 and up Isuzu's?
3) where is the link to the company that was offering heavy duty rebuild kits?

Thanks for any input :-)

My tranny problems this time came all of a sudden on a road trip pulling a very light trailer. It made it 3.5 hours going 80mph all the way there with no problems, but then when I was coming back to Houston it would not shift out of 2nd gear and tranny light started flashing. I got on the highway and by turning the engine off while rolling in neutral going about 40mph I somehow got the tranny to shift up to 3rd and OD once and then set the cruise control and then the tranny would pulsate RPM's anytime it got close to needing to down shift. The downshifts were harder and more inconsistent then normal. I cleared the code from the computer while driving in OD and it did not come back until I slowed down and it shifted back down to first. I checked my transmission level the next time I drove it, and it was a little low. I topped it off and it did not help anything, it is still throwing the tranny code immediately and will not shift out of 2nd gear until it redlines and even then it normally just stays in 2nd. This time when I clear the code it comes back immediately. The code is not coming up as anything recognizable. Sometimes it just says "?" For the code. Regardless the VX is not drive-able at the moment. Should I try the solenoids? Or just get the HD rebuild kit and have it rebuilt or find that company that rebuilds them and buy a rebuilt on?

[Mile High VX]

you might give a try here:

http://www.vehicross.info/forums/showthread.php?t=25553

[LittleBeast]

www.vehicross.info/gallery/showfull.php?photo=24788

www.vehicross.info/gallery/showfull.php?photo=24790

www.vehicross.info/gallery/showfull.php?photo=24791

Doesn't look good so far.....

[creeg]

This seems to have some similarities to the issues Im having. My ongoing and unsuccessful attempts to fix it are here:
http://vehicross.info/forums/showthread.php?threadid=23124

I didnt know about the trans fluid level being so finicky up until now though. Since I have the underbody plates, its hard to get to the trans fill plug.

I dont know if anything in my postings help, but its worth a read.

[Hiredgoon]

I've been experiencing the same issue, but largely when it's raining or snowing, or otherwise damp or humid out. I'm wondering if there's some sort of an electronic shift module that might have a weak or torn seal, and that there's some sort of a short in it? Like I say, it only happens when it's wet out, but it's not just 2-3rd gear, it's all the way up the spectrum, and in and out of reverse as well.

I'll post if I manage to solve it. It used to be only occasionally when it was particularly wet or rainy, but now it seems to be consistently whenever the weather turns wet.

I've replaced the fluid twice during which this was an issue, to no effect, being very careful of level, and added the Lucas anti slip the last time.

[LittleBeast]

Well after chatting with Marcus for a while it seems that when Aamco "rebuilt" my transmission it seems that they probably did not rebuild it at all. I ordered the new solenoid kit for an '01 VehiCross' 4L30E and the two solenoids that go in the small tranny pan do not fit, which means that when Aamco "rebuilt" my tranny they took my factory tranny out and put a different one back in. One that was designed for the 99-00 VehiCross. Which is why when I originally picked it back up from Aamco the shifts felt WAY different, and it would pulsate around 30-40mph occasionally feeling like it didn't know what to do up shift or downshift. Which would explain why in the first year after they "rebuilt" it I had to go back to them multiple times, and then finally a year later I took it to a different Aamco location and they had to "rebuild" it again only a year later. And this would explain how even though I do not drive the VehiCross that much at all it has blown the tranny out again, because it is the wrong 4L30E. They changed a few things between the '00 and '01 VehiCross transmissions. So I have the wrong tranny in my '01 more then likely, since the new parts for the '01 tranny won't fit.....

[VX crazy]

Remember to keep in the back of your head Ryan I still have my tranny from my 2001.

[VX crazy]

Oh and I would be raising a stink with them.........

[Marlin]

Huh,had no idea there were differences in the 4L30E within the VX model years. I know the various 4L30Es have different guts based on application. I wonder if it would be better to get one out of a trooper (heavier vehicle) The one in mine came out of a late model trooper, had 80+K miles on it. I haven't had a problem since, towed trailer thousands of miles now, never touched the fluid.

[Y33TREKker]

I've been experiencing the same issue, but largely when it's raining or snowing, or otherwise damp or humid out. I'm wondering if there's some sort of an electronic shift module that might have a weak or torn seal, and that there's some sort of a short in it? Like I say, it only happens when it's wet out, but it's not just 2-3rd gear, it's all the way up the spectrum, and in and out of reverse as well.

I'll post if I manage to solve it. It used to be only occasionally when it was particularly wet or rainy, but now it seems to be consistently whenever the weather turns wet.

I've replaced the fluid twice during which this was an issue, to no effect, being very careful of level, and added the Lucas anti slip the last time.
It could be that moisture is getting into the electrical connectors near the rear of the transmission that I described in the following post. After experiencing a similar problem awhile back, I cleaned those connectors and waterproofed them as best I could and haven't had the problem since.

http://www.vehicross.info/forums/showpost.php?p=142763&postcount=13

If that's not it, there were a few other suggestions in the thread that might help too.