11' Denali - DOD survivor, but now transmission shot?!?!

[2011DenaliInKY]

My first thought is battery. I reckon that the new battery is low on juice or has a bad cell. Charge it up and try again. These trucks go nuts when the voltage is low in any of the modules. Some begin to get squirrely at 11 volts, others go nuts at 9 and so on. This includes the TECHM in the transmission. Check your grounds sure, check the wires and connectors on the battery, making sure they are tight and corrosion free.

Battery tests good, I’ve got 12.7 VDC just sitting, 14.6 while running, passes the test on my digital battery tester. I took all the grounds off today, cleaned each and reinstalled, and can read 0.0 ohms from each ground connection back to the negative terminal (with batt disconnected). I pulled the trans connector off today to check all the pins and plugs, all looked good there. I’ve traced the harness back up to the engine compartment and haven’t found any issues, that I can put my hands on anyway. I’m so freakin frustrated and confused by all this. I didn’t have the first symptom of a trans issue whatsoever before my lifter failed ‍

 

[Geotrash]

Thanks Dave, if a man were to drop the pan and pull the valve body assembly out, is there a kit you’d recommend, or I guess that would depend on what I found. I’m just trying to get my ducks in a row before I pull it apart to take a look. I’ve got limited experience with trans internals, and ive tried to get my interwebs diploma on it, but most of the videos show a unit out of the vehicle all torn apart.

Yes, you can go to the Sonnax website, and get everything you need. They have a kit for it. There are a couple of other optional bits from transgo also.

 

[THarber]

Yes because chances are it is not your original ECM.

Tim

 

[swathdiver]

Battery tests good, I’ve got 12.7 VDC just sitting, 14.6 while running, passes the test on my digital battery tester. I took all the grounds off today, cleaned each and reinstalled, and can read 0.0 ohms from each ground connection back to the negative terminal (with batt disconnected). I pulled the trans connector off today to check all the pins and plugs, all looked good there. I’ve traced the harness back up to the engine compartment and haven’t found any issues, that I can put my hands on anyway. I’m so freakin frustrated and confused by all this. I didn’t have the first symptom of a trans issue whatsoever before my lifter failed ‍

More times than we can count, batteries passed tests and were later to be found faulty anyway after the owner exhausted all other options and revisited the battery. Borrow another known good one just to be extra sure when all else is tried.

My memory escapes me, if you sent your computer out for tuning, you should run the Service Learn Adapts for the transmission just in case. The first few moments after doing it the trans feels funky but then settles down nicely and just gets better and better with time. We normally only do this after TECHM replacement or an internal repair to the transmission or after tuning.

 

[2011DenaliInKY]

Well out of pure frustration last night I went ahead and pulled the transmission pan, filter and TECHM/valve body assembly. I disassembled the valve body, hoping to find a shrunken check ball stuck in the separator plate, but no such luck. The check balls all looked fine and were the same size, none looked shrunken and worn. All of the valves felt smooth, no binding. A very minimal amount of fine metal accumulated on the magnet in the pan, but no other metal found. Nothing clogging the TECHM screen/filters, and all of the seals looked good. I went ahead and put it back together, I know, not all would agree with that, if I’d had time and weren’t chasing a gremlin it would’ve been a prime opportunity to install a shift kit to remedy some of the known valve body issues, at least. But I put it all back together, filled it with fluids, went for a drive and still have the exact same issue. I’m starting to wonder if the 1-2-3-4 piston isn’t cracked, as from what I’ve read, this is a common problem. Does anyone know if that would only affect gears 1-4, because that’s pretty much my issue. Once I get it up to 55 mph or so, it cruises along just fine, I just can’t stop at a light and get it going again, just feels like it’s slipping.
I’ve still got the original battery that I took out recently, it was still good, just going on 5 years old so I swapped it out. That’ll be easy enough to give it a try and see what happens.
I don’t have any codes present on the dash, if I had a TECHM code, would it show on the dash as some kind of warning? I’ve got a generic OBD-II code reader, but it only give engine info I’m pretty sure, and very limited amounts.

 

[2011DenaliInKY]

Oh, and for the Service Learn Adapts, do I have to have a diagnostic tool to perform that learning procedure? Or could a man do it manually somehow?

 

[Headsup9550]

I can't believe nobody here is familiar with this. 6l80e failure is extremely common after arm/dod lifter failure. A lot of people don't associate the two as being related because very few people know how a 6l80e works or even that it works in a completely different manner than conventional automatic transmissions. When the engine has a dead cylinder for any reason actually, the strategies used to apply torque management are working off data that it doesn't know how to process. The operation of a 6l80e is based around torque management. It uses this data much more than any other transmission and if a truck is driven with a failed lifter for more than just getting it home, it will smoke a 6l80e. If you've done it and gotten away with it, there's a good chance that you've compromised the transmission and just don't know it..

 

[swathdiver]

Oh, and for the Service Learn Adapts, do I have to have a diagnostic tool to perform that learning procedure? Or could a man do it manually somehow?

Need the proper scan tool like a Tech-2.

I can't believe nobody here is familiar with this. 6l80e failure is extremely common after arm/dod lifter failure. A lot of people don't associate the two as being related because very few people know how a 6l80e works or even that it works in a completely different manner than conventional automatic transmissions. When the engine has a dead cylinder for any reason actually, the strategies used to apply torque management are working off data that it doesn't know how to process. The operation of a 6l80e is based around torque management. It uses this data much more than any other transmission and if a truck is driven with a failed lifter for more than just getting it home, it will smoke a 6l80e. If you've done it and gotten away with it, there's a good chance that you've compromised the transmission and just don't know it..

Didn't know this, can you elaborate for us please?

How does the trans get smoked?

What if we have removed most of the torque management?

 

[THarber]

I've never heard of a transmission failure due to a DOD issue but all the more reasons to go thru the ECM relearn as I posted before.

OP try this: https://www.replicarclub.com/how-to-reset-transmission-control-module-chevy/

Tim

 

[Geotrash]

I can't believe nobody here is familiar with this. 6l80e failure is extremely common after arm/dod lifter failure. A lot of people don't associate the two as being related because very few people know how a 6l80e works or even that it works in a completely different manner than conventional automatic transmissions. When the engine has a dead cylinder for any reason actually, the strategies used to apply torque management are working off data that it doesn't know how to process. The operation of a 6l80e is based around torque management. It uses this data much more than any other transmission and if a truck is driven with a failed lifter for more than just getting it home, it will smoke a 6l80e. If you've done it and gotten away with it, there's a good chance that you've compromised the transmission and just don't know it..

First I've heard of this too, and I would love to learn more. If you have any more reading you can suggest, I suspect the whole group will appreciate it. I learn new things here every day, and have been around a few years now.