broken trans!

[duratothemax]

nah just kidding not really...

third gear limp

P0700 (duh)
P0842
P0840

Tried resetting it a couple times...either a problem with the C shift solenoid or something goofed in the wiring.....

I will be troubleshooting it with the GM eSI instructions (idiot proof), but I thought I'd ask....mike ever seen this before? What was the problem?

Most annoying thing tho is waiting for the darn trans to cool off so I can get under there and work on it!

things that make you go hmmmm...

 

[Mike L.]

Those are Pressure Switch Manifold codes. Ususally stuck valves. It is an electrical code ( s ) cause by a hydraulic problem most times.

 

[duratothemax]

I thoght SI would be more of a help. It asks "Does the scan tool indicate TFP SW. C status is ON when grounded and OFF when open?"

according to my tech 2, engine on, park/neutral, check engie light on, yes, TFP switch C is "on". So I answer "yes" to that question and SI just tells me to "go to diagnostic aids" and doesnt give any further info.

 

[duratothemax]

is there any possibility it could be an electrical short? Or should I just put the truck up a lift and drop the pan?

thanks for the help mike

I guess dropping the pan wouldnt be completely bad...it woudl give me an excuse to switch back to transynd...right now the trans is ~25% transynd and 75% dex III because when I hit the deer and lost all the fluid, I refilled it with dex III...plus Ive got a 5 gallon pail of transynd in the garage here....

when I command C sol off and on with the tech 2 it seems to turn on and off correctly? Or is that function not really a good test of anything?

 

[duratothemax]

Im going to first check the wiring..



mike dare I say it....this is 'probably' a result of me screwing around with my harness when I wired in the 4th gen TCM :

 

[duratothemax]

If I clear the code and start the truck, the DTC doesnt appear...then I go to trans data and watch all the solenoid and PSM data. I shift to drive and the PSM and solenoids change....then 1 second later you can feel VERY VERY subtle bumps in the trans, simualtaniously on the Tech 2, the TCM is shuffling things around, solenoids turning off then on, PSM changing, then it gives up and 5 seconds later sets a DTC.

 

[duratothemax]

mike does this look like excess crap build up on the spin-on?

Its not any more than normal, at least on my trans. Depending on how long its been since Ive changed the spin-on, its ALWAYS had this general amount of build up on the magnet.

This spin-on was changed ~8,000 miles ago.

 

[Turbotug]

That's about what mine usually looks like a 5k.

 

[SmokeShow]

That's about what mine usually looks like a 5k.

Ditto.

 

[duratothemax]

alright...im going to pull the pan this afternoon...mike are you going to be really busy today? I might be giving you a call..

 

[duratothemax]

hm. My truck likes me?

let it sit and cool over night with the TCM unplugged, changed the spin-on, and its good as new. I love 7 dollar transmission repairs!

I forgot to plug the TCM back in when I first started it (after it had been sitting overnight) so it immediatly went to hydraulic default....maybe that combined with the new spin-on flushed it out or knocked something loose? Who knows...

I will be flushing it with Transynd tho, and changing the internal filter at the same time. Mike You'll get a call from me in about 2 seconds to buy a filter loc...for 20 bucks I might as well do it while Im in there.

 

[Mike L.]

I had no power on my street from 2 till ? when I went home.

 

[BIG DIPPER]

If I clear the code and start the truck, the DTC doesnt appear...then I go to trans data and watch all the solenoid and PSM data. I shift to drive and the PSM and solenoids change....then 1 second later you can feel VERY VERY subtle bumps in the trans, simualtaniously on the Tech 2, the TCM is shuffling things around, solenoids turning off then on, PSM changing, then it gives up and 5 seconds later sets a DTC.

E-shift valve....you need the "special honing tools and special springs" that a "backyard trans builder" doesn't have.......Sound familiar Mike?

 

[duratothemax]

ok the trans is working fine, but my converter lockup is wierd. It takes forEVER now. Same TCM, didnt touch anything. Ill floor it, 1-2, 2-3 runs out kinda far and it fumbles it VERY slightly, 3-4...converter lockup doesnt happen until sometime around 3-4 or early in 4th gear. I tried putting it in fast learn AND resetting taps...didnt work...Im going to pull the pan and change tyhe fluid and internal filter. Should I pull the solenoids and clean them out?? I need it fixed by saturday cause Im going to the track!

the actual shifts are fine, it just fumbles converter lockup at WOT badly.

And another question. WHY does converter lockup take so long. You can run 50 different TCM's, program WOT lockup at 15mph the split second it does the 1-2, but it doesnt happen unless you have a co-pilot. Why does the TCM not lockup the converter when the programming tells it to? Does it just get freaked out with the big power and put lockup "on the back burner" for a second?

annoying!

 

[turbo-max]

post whore!!! lol just messing with ya ben

 

[duratothemax]

mike thanks for the tech support today.

I went to the alli dealer and they didnt have the F trim solenoid spring cap, but I ordered it.

I drove around with the tech 2, it is not an electrical problem. The TCM just refuses to command the TCC solenoid on at the right time.

What parameters need to be met in order for the TCM to start pulsing on the converter? Is there something INSIDE the trans/valve body that could be messing with the TCM and preventing it from wanting to lock the converter? This just seems like too much of a coincedence to start being stupid (TCC lockup) RIGHT after I had that C-shift solenoid problem/codes. Im going to check my wiring...Im suspicious.

Mike I looked at my input speed sensor...The connector/plug end of it is kinda facing down towards the ground. Is that right?

It got too late and I didnt get around to draining the pan or anything. The guy at the allison dealer said I shouldnt need to ever change the internal sump filter, but I got one anyway.

Im going to try a 2001 TCM next...see if it has any difference. It seems that anything over ~20% throttle, converter lockup schedule gets retarded. Below that it locks the converter early, when its supposed to.

Also, I did a bunch of stop/WOT/stop/WOT runs. I did like 15 of them and ONE time it locked early/normally like it should...either a speed sensor is weak or wiring, im 99% convinced...

 

[Mike L.]

Ben
I believe the ISS should point at 4:00 oclock. Moniter the ECT because if it's too cool L/U will never be commanded. The Alli temp sensor is in the PSM. It's the funny looking resistor.

 

[dmax tim]

Ben
I believe the ISS should point at 4:00 oclock. Moniter the ECT because if it's too cool L/U will never be commanded. The Alli temp sensor is in the PSM. It's the funny looking resistor.

any way to get around the sensor Mike?

I get tired of driving 5 or more miles in the winter before it locks up.

 

[Mike L.]

any way to get around the sensor Mike?

I get tired of driving 5 or more miles in the winter before it locks up.

Probably but the Alli would never warm up which is bad.

 

[duratothemax]

Ben
I believe the ISS should point at 4:00 oclock. Moniter the ECT because if it's too cool L/U will never be commanded. The Alli temp sensor is in the PSM. It's the funny looking resistor.

my trans is definetly above 80*! It actually runs a little warm...right around 200*. One/two ticks over 200 when I really beat on the trans. I have one of your coolers mike, its just always run warm.

tim go into EFILive and program the TCM to allow lockup below 80* trans temp. I wouldnt do this though.

Im going to check wiring tonight.

Mike how would I know if my converter is blown? I monitored slip speed and once its locked it does not slip at all...does that mean its ok? Or could something else be blown in it thats allowing the engine to stall higher than normal, creating more of a difference between input and turbine speed, making the TCM not want to lock up? Does there have to be less than "X" difference in RPM between the two speeds befor lockup is allowed? For some reason my converter doesnt feel quite as "tight" as I rmemember, but its probably just me being paranoid, or the fact that its not allowing lockup, so the engine is blowing right thru the converter at WOT unlocked.

hmm