6L80 - P0776 Error + No Move Condition

[08ColoRADo]

Sounds good. I have the ATSG manual so I should be able to use that and diagnose any potential valve body issues.

[08ColoRADo]

Repeat post.

[08ColoRADo]

So after much delay I did manage to pull the valve body and check the whole thing over. Everything was where it belonged, and each individual valve looked good for the most part. The only bad news that I discovered was a small-ish piece of trash that was located in one of the pathways of the valvebody when I looked over the checkballs. I don't recall it being there when I went through this the first time, so I wonder if it was stuck somewhere else and managed to free itself after I ran the trans the first time after its rebuild.

So now I was confident that everything I did the first time was accurate, and double checked it all just to be sure. Put it all back in the trans and refilled it with fluid. Cranked it over and found that I had made some progress, but we're not at 100%. The good news is that drive works as it should, kinda. I have 1st gear, and can watch it pick up speed with throttle and go into 2nd gear, but then it tops out and won't shift into third. I also don't have reverse still, and neutral is a bit of a conundrum.

When you go from park to reverse, it drops into gear, and moves FORWARDS for one tenth of a tire rotation before making a clunk and then going nowhere. Then you drop it into neutral, and the tires start turning forwards. Then you drop it into drive, and it behaves normal for 1st and 2nd gear, and then stays there regardless of throttle input. Step on the brakes and the tires stop and start as normal, so torque converter is definitely functioning. Put it back into neutral, and tires stop as they should, (so neutral is working when coming out of gear, but not when going into it). Back through reverse, no movement, and back into park. See attached log for data backing this up.09-22-23 Trans Log 1-2 Shift.hpl

Sounds like a 3-5-R issue to me, but looking for confirmation before I dig into it again. Thanks.

[TransGo Robert]

So after much delay I did manage to pull the valve body and check the whole thing over. Everything was where it belonged, and each individual valve looked good for the most part. The only bad news that I discovered was a small-ish piece of trash that was located in one of the pathways of the valvebody when I looked over the checkballs. I don't recall it being there when I went through this the first time, so I wonder if it was stuck somewhere else and managed to free itself after I ran the trans the first time after its rebuild.

So now I was confident that everything I did the first time was accurate, and double checked it all just to be sure. Put it all back in the trans and refilled it with fluid. Cranked it over and found that I had made some progress, but we're not at 100%. The good news is that drive works as it should, kinda. I have 1st gear, and can watch it pick up speed with throttle and go into 2nd gear, but then it tops out and won't shift into third. I also don't have reverse still, and neutral is a bit of a conundrum.

When you go from park to reverse, it drops into gear, and moves FORWARDS for one tenth of a tire rotation before making a clunk and then going nowhere. Then you drop it into neutral, and the tires start turning forwards. Then you drop it into drive, and it behaves normal for 1st and 2nd gear, and then stays there regardless of throttle input. Step on the brakes and the tires stop and start as normal, so torque converter is definitely functioning. Put it back into neutral, and tires stop as they should, (so neutral is working when coming out of gear, but not when going into it). Back through reverse, no movement, and back into park. See attached log for data backing this up.09-22-23 Trans Log 1-2 Shift.hpl

Sounds like a 3-5-R issue to me, but looking for confirmation before I dig into it again. Thanks.

Right now it is acting up as if your 1-2-3-4 clutch was welded together or teh manual valve is not engaged. I am thinking more manual valve because it goes to neutral when you go back to it from drive. You have first gear in neutral and in D6 but only when you don't give it gas, when you give it throttle it is slipping badly. But once it shifts to 2nd it holds good in that recording (not sure if that was on the road or wheels off the ground so it might not be holding that good). Then the no upshift after second gear is a separate issue, the computer is simply never commanding it. That's a command issue not an internal issue. At this point, the first thing to do is to drop the pan and see if the manual valve is connected and moving as it should when you move the shifter to the P/R/N/D position.

[08ColoRADo]

When you say manual valve, you mean the plastic piece that aligns with the nub on the metal shift plate and slides in/out of the valve body? This is definitely aligned appropriately. I had that issue the first time I reassembled the valve body and ensured it was correct during reassembly this time.

All testing was done with wheels off the ground in the garage, so no real determination to be made on how well it's holding each gear. I'll go out this evening and try to force it into subsequent gears after 2nd and see what it does.

Does this also explain the no reverse issue?

[TransGo Robert]

When you say manual valve, you mean the plastic piece that aligns with the nub on the metal shift plate and slides in/out of the valve body? This is definitely aligned appropriately. I had that issue the first time I reassembled the valve body and ensured it was correct during reassembly this time.

All testing was done with wheels off the ground in the garage, so no real determination to be made on how well it's holding each gear. I'll go out this evening and try to force it into subsequent gears after 2nd and see what it does.

Does this also explain the no reverse issue?

This is what the manual valve looks like in the red box I added to this screenshot: Manual Valve.png

Since the previous log was with the wheels off the ground and it slipped in first, I doubt it will move much if at all when you try it on the ground. As for reverse it is not workign because your 1-2-3-4 clutch is applied so it causes it to bind up solid trying to go forward and reverse at the same time. If it is not the manual valve that is not indexed, then something is not assemble correctly in the valve body. A checkball missing or at the wrong place, valve inserted backwards or something like that, wrong separator plate for valve body type etc..

[08ColoRADo]

The manual valve is 110% in the correct place. Additionally, I took every part of the valve body apart when I examined it last week, and reassembled correctly per the ATSG manual. Nothing that all check balls were in the correct location. I'm at a bit of a loss if that's the only recommendation. The only possibility would potentially be the separator plate, but i believe I just re-used the original.

[TransGo Robert]

The manual valve is 110% in the correct place. Additionally, I took every part of the valve body apart when I examined it last week, and reassembled correctly per the ATSG manual. Nothing that all check balls were in the correct location. I'm at a bit of a loss if that's the only recommendation. The only possibility would potentially be the separator plate, but i believe I just re-used the original.

It is going to be either be in the valve body or a solenoid but since it changed since you went back in my best guess is that it is in the valve body. You had nothing before, now you have forward in neutral, bind in reverse, and slipping but pulling some in drive. That screams assembly error. Not sure I would fully trust the ATSG manual, lots of mistakes in books from time to time and depending on the year of the valve body you have in there things change. Best thing to do to make sure everything is at the right place and a match for your application is to go to the product page for our 6L8 CS-TCC kit and then click on #Documents" to get the instructions in PDF. All the info you need for each valve body plate combo is in there. https://transgo.com/product-details/...regulator-kit/

[08ColoRADo]

Woof. Alright. Guess we'll put valve body tear down #3 on this week's plate.

As per usual. Thanks for the quick and helpful replies.

[08ColoRADo]

Valve body tear down #3 reveals nothing out of place, as expected. The trans-go instructions match the ATSG manual on location of checkballs, valve assembly, etc.

My valve body is a type 2, version 1 with the seven checkballs. I'm going to order a type 2 version 2 and an additional checkball to update to the newest style, as recommended in the Trans-Go instructions. I'll probably also order the clutch valve and tcc regulator valve kit just to throw parts at it so that it doesn't go back exactly the same as it came out in an effort to hunt for change.

[TransGo Robert]

I went back and read the whole thread from the begining to refresh my memory and something is not clear. Before you pulled the valve body the second time, you said it had no reverse but I am not clear if it was binding like after going through the valve body the third time, or if it felt like neutral?

[08ColoRADo]

After the initial rebuild when I tried it. It was like a true neutral. No movement. Then I went in and double checked the valve body and everything was in the right place but I discovered a piece of trash in one of the valve body passages. Re-assembled. And we got binding in reverse then 1st in neutral, and 1st/2nd in drive. Now we are disassembled again.

[TransGo Robert]

After the initial rebuild when I tried it. It was like a true neutral. No movement. Then I went in and double checked the valve body and everything was in the right place but I discovered a piece of trash in one of the valve body passages. Re-assembled. And we got binding in reverse then 1st in neutral, and 1st/2nd in drive. Now we are disassembled again.

Ok so I had it right, I just was starting to doubt myself now. Something changed after the second valve body disassembly, maybe it was that piece of metal but man that is odd. Since you originally bought the transmission and were told it had no reverse, I am now thinking it probably has a bad solenoid in the TEHCM. About the only think that makes a little bit of sense.

[08ColoRADo]

Bad solenoid in the TEHCM would make sense given the original error code was a P0776 stuck solenoid code. I'm going to throw the #8 checkball in and the new style separator plate and the trans go clutch valve kit. A quick(ish) attempt at a final fix and much cheaper than a new valve body/TEHCM combo.

To be honest. If it pans out that I need a new computer, I may just end up ordering a new trans. Not what I want to spend dollars on. But if I'm going to blow hundreds on a attempted fix, I'd probably be better off just getting a whole new guaranteed working trans.

[TransGo Robert]

Bad solenoid in the TEHCM would make sense given the original error code was a P0776 stuck solenoid code. I'm going to throw the #8 checkball in and the new style separator plate and the trans go clutch valve kit. A quick(ish) attempt at a final fix and much cheaper than a new valve body/TEHCM combo.

To be honest. If it pans out that I need a new computer, I may just end up ordering a new trans. Not what I want to spend dollars on. But if I'm going to blow hundreds on a attempted fix, I'd probably be better off just getting a whole new guaranteed working trans.

The TEHCM is sold by itself, you reuse your valve body.

[08ColoRADo]

Update. Finished valve body inspection/rebuild #3. Installed the 8th checkball and the new type 2 version 2 separator plate/gasket as well as the trans-go clutch valve kit.

Unfortunately. There was no change. Everything acts exactly the same as it did after the 2nd time I had it out and in. Still locks up in reverse after attempting to spin forwards 1/8th a rotation. Still has 1st in neutral. And 1st/2nd in drive.

[TransGo Robert]

Update. Finished valve body inspection/rebuild #3. Installed the 8th checkball and the new type 2 version 2 separator plate/gasket as well as the trans-go clutch valve kit.

Unfortunately. There was no change. Everything acts exactly the same as it did after the 2nd time I had it out and in. Still locks up in reverse after attempting to spin forwards 1/8th a rotation. Still has 1st in neutral. And 1st/2nd in drive.

I just looked at the hydraulics and now I am convinced your 1-2-3-4 clutch pack is welded together. i thought it was the solenoid that was sending pressure to it all the time, but it can't until you put the shifter in drive. There is no fluid going to the circuit in neutral no matter what the solenoid does. So don't waste money on a TEHCM, it has to come out.

[08ColoRADo]

Figures we'd end up going that way. Guess I'll get it pulled and see what looks messed up. Hopefully nothing too crazy as it's all fresh internals, but we'll see.

[radrace19]

I thought the TCM2650 sent RPM and TPS data to the trans along with the required torque data. Have you used the TCM2650 software to make sure you are getting the RPM and TPS data?
-Greg