2017 Tahoe Sudden Transmission Issues

[Craddock]

I bought my wife a 2017 Tahoe about 4 years ago. It was just over the warranty limit on the garbage AC when I bought it (IDR if that was 75k or 80k miles). Other than the garbage AC it has been a great vehicle until today. It's our everyday vehicle for anything we do together as a family.

So the Tahoe was a rental before we had it. Hopefully it was taken care of, but who knows. Today she went to take her parents to the airport after visiting us. It's about a 4 hour drive one way to save 500+ on a short flight. So she went, dropped them off, then started back home.

She calls me and tells me the vehicle has reverse only, no drive. I tell her to try putting it in manual and trying the rest of the gears to see if anything grabs because it has no check engine light at the time. It goes forward in 3-6 for a few minutes, but then she calls me and says it won't go in any gear at all. Check engine light is solid now, showing P0700 and P 0796. I have her check the temp and the transmission is at 216. By this time she's parked on the side of the road and I tell her to turn it off and wait for me to come pick it up with a trailer. 90 minutes later, it starts up and drives itself up on the trailer in 4WD just to get off the interstate. 2 hours later, it starts up and functions like normal in the driveway. I checked the transmission fluid and it's full, but dark. Allergies are kililng me right now so I didn't even attempt to smell it. It wasn't horrible or even bad from what I could smell.

Previously it hasn't had any issues since we've owned it. I had the transmission go out in my 2011 Sierra and you could see it coming a few weeks in advance. No warning, no slipping here.

I'm going to go for a hail Mary and change out the fluild and filter tomorrow to see if I can get that little sliver or hope. Lost my job last week so I'm due for some good luck.

Any suggestions to check on it to verify what exactly the issue is?

Thanks

 

[DuraYuk]

Most likely forward clutches are borderline toast. This is very common. Fluid changes help before the problem manifests itself. You could try and do the fluid change but my gut and experience is saying she needs a rebuild.

Good luck.

 

[NickTransmissions]

I bought my wife a 2017 Tahoe about 4 years ago. It was just over the warranty limit on the garbage AC when I bought it (IDR if that was 75k or 80k miles). Other than the garbage AC it has been a great vehicle until today. It's our everyday vehicle for anything we do together as a family.

So the Tahoe was a rental before we had it. Hopefully it was taken care of, but who knows. Today she went to take her parents to the airport after visiting us. It's about a 4 hour drive one way to save 500+ on a short flight. So she went, dropped them off, then started back home.

She calls me and tells me the vehicle has reverse only, no drive. I tell her to try putting it in manual and trying the rest of the gears to see if anything grabs because it has no check engine light at the time. It goes forward in 3-6 for a few minutes, but then she calls me and says it won't go in any gear at all. Check engine light is solid now, showing P0700 and P 0796. I have her check the temp and the transmission is at 216. By this time she's parked on the side of the road and I tell her to turn it off and wait for me to come pick it up with a trailer. 90 minutes later, it starts up and drives itself up on the trailer in 4WD just to get off the interstate. 2 hours later, it starts up and functions like normal in the driveway. I checked the transmission fluid and it's full, but dark. Allergies are kililng me right now so I didn't even attempt to smell it. It wasn't horrible or even bad from what I could smell.

Previously it hasn't had any issues since we've owned it. I had the transmission go out in my 2011 Sierra and you could see it coming a few weeks in advance. No warning, no slipping here.

I'm going to go for a hail Mary and change out the fluild and filter tomorrow to see if I can get that little sliver or hope. Lost my job last week so I'm due for some good luck.

Any suggestions to check on it to verify what exactly the issue is?

Thanks

Could be

1. Stuck #1 check ball which likes to wear or
2. TEHCM shift solenoid #2 has failed, requiring TEHCM replacement

Both can be fixed w/trans in vehicle

1. Low sprag has rolled and failed
2. 1-2-3-4 clutch is burnt due to a cracked piston (likely given the smell of the fluid)

Both require the trans to come out for overhaul which is what your transmission likely needs.

Check out my 6L80 Info thread for input on rebuild profile, parts selection, etc (link is in my signature) - let me know if you have any addl questions.

 

[Craddock]

Appreciate the replies from everyone. We're moving across the country in a few weeks, pulling a trailer behind the Tahoe. Just went ahead and had it replaced to move along without worrying about stranding everyone mid trip.

 

[Seanslane]

Appreciate the replies from everyone. We're moving across the country in a few weeks, pulling a trailer behind the Tahoe. Just went ahead and had it replaced to move along without worrying about stranding everyone mid trip.

If you replaced it with another Chevy dealer transmission, then I would sell it before the warranty is up. Those transmissions are junk. Converters fail and eat the tranny up. Just dropped 7k on one for our 2017. Garbage.

 

[mikeyss]

The 6L80's are NOT junk, and they have had less failures than the 700R4/4L60 4 speed transmissions. The 6L80 torque converter is the weak spot, and if it's addressed early enough, this trans will last over 200K miles.

 

[RobH]

My transmission went at 121K miles. Typical Torque Converter Clutch (TCC) problem sent metal through the transmission. Replaced with GM reman to get the 3year/100K warranty. It now has one year on it and 15,000 miles.

Apparently, the Transmission Control Module (TCM) is set up to allow the TCC to slip practically all the time to give it extra smooth shifting and to mask the AFM/DOD switching back and forth between 8 cylinder and 4 cylinder operation.

I am getting an HP Tuners package from Summit Racing later today. My first step will be to turn the AFM off to hopefully avoid one of the AFM lifters failing and taking out the camshaft, killing the engine.

My second action will be to set the TCC target slip to 0 RPM in all the gears. I know that many people advocate disabling TCC lockup in gears 1-4. I don't plan to do that. With the TCC unlocked, the churning of the fluid in the torque converter creates heat. I'm in South Texas. Nuff said.

I also want to raise the shift speeds and TCC lockup speeds to avoid operating the engine trying to run at 1,200 to 1,500 RPM with the TCC locked up in 6th gear instead of in 5th gear, thus lugging the engine. Same applies to the lower gears' upshifts and TCC lockup speeds.

I will be reporting my progress in the following thread.

HP Tuner for 2016 Tahoe L83/6L80

I want to get the Active Fuel Management (AFM)/Displacement on Demand (DOD) turned off in my 2016 Tahoe. At the moment I am driving with the transmission in M5 which prevents V4 operation. If I operate the transmission in M6, AFM remains disabled in 1st - 5th gears, but in 6th the AFM is...

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