2021 Tahoe HC Transmission failure @600miles

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BentleyArnage

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I agree with you on the "relearning"for most vehicles, but what I don't understand is we got the Tahoe with 20 miles on it and it was shifting just fine. What I'm trying to say is was it programmed like that from the factory and didn't have to learn our driving habits, or was it trans already starting to slip from the gate? I'm torn on what to believe here. Although I wanted to test out the power of the 6.2, I couldn't because of the break-in period, but even driving normal it didn't shift hard like it does now.
To your point on the fluid, I chuckled when he said better fluid and then I forgot to ask what he meant, but I think I'm going to call back and ask what he meant by that. Thank you!

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The vehicle is programmed from the factory to work in a way that is pleasing to the customer. It doesn't relearn from new, it's set up that way on a very sophisticated programming system. The only relearn involved is to adapt to the way you drive as you drive. When they took the unit apart at the dealership, it's going to start over without the nice factory baseline programming. You're essentially reprogramming the vehicle based upon your driving but in real time and from the beginning. As for better fluid, that flies in the face of the factory requirements as they are very specific what goes in these units. I'd want to know what this better fluid is and have this in writing. It wouldn't be the first time a dealer got fancy with a transmission(something dealers are woefully ignorant about) and decided it needed something different. Good luck with your new baby!
 
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TAHOEpeful

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Hello everyone, sorry I never updated the thread about transmission issue, life has kept me busy. So to catch everyone back up, the valve body was changed and we were told the transmission had to relearn our driving style. It's slowly begin shifting smoothly for about 1500 or so miles. Then, out of nowhere it began shifting very hard again. We would notice a loss of power in an a slamming hard shift while traveling at either parking lot speeds or 25 mph. We never returned back to the dealership because of that issue, due to me being disabled and us having four kids. The first time they had the Tahoe in, we are given a base model Acadia, that we had to all squeeze into and was very uncomfortable for me, so we were hesitant to have to lose the Tahoe again. Okay, so we dealt with it like that for a couple months, until 2 days ago. My wife, the primary driver of the Tahoe, calls me on the way home from school and says that the Tahoe is driving funny. It would not accelerate normally, shift properly, or rev above 2500 rpm. She was so concerned that she had a friend follow her home from school in case she broke down. Yesterday, 11/12/2020, I called the dealership and told them the issue, they had to spring it in again. My wife took it in on her own to explain the issue because she's been primarily driving it. They gave her a base model Blazer andsent her on her way. A couple hours after dropping the Tahoe off at the dealership, they call to tell her that they were going to have to replace the transmission! [emoji2363] Out of frustration she called GM corporate to complain. She was transferred to a supervisor and they mentioned something to her about a buyback. So there's the update, not sure where anything is going to go from here, but I promise I will keep everyone updated! Oh BTW, the Tahoe only has 3,000 mi on it. (4,828 km) for anyone reading outside of the US. Wish us luck, and stay tuned! [emoji1431]

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OR VietVet

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Thanks for that update. A new transmission, with likely dealer bulletin upgrades, should fix the problems, hopefully.

I am assuming that besides the transmission issue, you love the vehicle.
 
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Thanks for that update. A new transmission, with likely dealer bulletin upgrades, should fix the problems, hopefully.

I am assuming that besides the transmission issue, you love the vehicle.
YES, we definitely love the vehicle, and that is why we are so upset. There is also one other issue that the dealer hasn't been able to narrow down. There seems to be something loose somewhere in the front suspension. Anytime we go over a bump, something is banging around and you can occasionally feel it in the steering wheel. My wife thinks it's the automatic running boards, but I don't see why that would vibrate in the steering wheel. I'm hoping this gets settled quickly and easily. Hopefully if they do a buy back, we get the exact same vehicle [emoji1431]

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Hope they take care of you this time around. :(
Thank you, I hope so also! [emoji1431] It's not a cheap vehicle, so I hope they treat us accordingly. We asked for a Cadillac loaner, but they said those were reserved for Cadillac owners. [emoji17]

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OR VietVet

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The steering wheel feeling should not be the running boards. Likely something in the steering/suspension. Can they duplicate the problem when they drive over a bump or when with you when you are driving? Sounds like they should be able to. Keep us in the loop as this all develops.
 

Rocket Man

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YES, we definitely love the vehicle, and that is why we are so upset. There is also one other issue that the dealer hasn't been able to narrow down. There seems to be something loose somewhere in the front suspension. Anytime we go over a bump, something is banging around and you can occasionally feel it in the steering wheel. My wife thinks it's the automatic running boards, but I don't see why that would vibrate in the steering wheel. I'm hoping this gets settled quickly and easily. Hopefully if they do a buy back, we get the exact same vehicle [emoji1431]

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Well not the EXACT same vehicle. :signs8:
 

B520044

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Hello everyone, sorry I never updated the thread about transmission issue, life has kept me busy. So to catch everyone back up, the valve body was changed and we were told the transmission had to relearn our driving style. It's slowly begin shifting smoothly for about 1500 or so miles. Then, out of nowhere it began shifting very hard again. We would notice a loss of power in an a slamming hard shift while traveling at either parking lot speeds or 25 mph. We never returned back to the dealership because of that issue, due to me being disabled and us having four kids. The first time they had the Tahoe in, we are given a base model Acadia, that we had to all squeeze into and was very uncomfortable for me, so we were hesitant to have to lose the Tahoe again. Okay, so we dealt with it like that for a couple months, until 2 days ago. My wife, the primary driver of the Tahoe, calls me on the way home from school and says that the Tahoe is driving funny. It would not accelerate normally, shift properly, or rev above 2500 rpm. She was so concerned that she had a friend follow her home from school in case she broke down. Yesterday, 11/12/2020, I called the dealership and told them the issue, they had to spring it in again. My wife took it in on her own to explain the issue because she's been primarily driving it. They gave her a base model Blazer andsent her on her way. A couple hours after dropping the Tahoe off at the dealership, they call to tell her that they were going to have to replace the transmission! [emoji2363] Out of frustration she called GM corporate to complain. She was transferred to a supervisor and they mentioned something to her about a buyback. So there's the update, not sure where anything is going to go from here, but I promise I will keep everyone updated! Oh BTW, the Tahoe only has 3,000 mi on it. (4,828 km) for anyone reading outside of the US. Wish us luck, and stay tuned! [emoji1431]

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My transmission has been updated twice in my 6000 miles of use. Not sure it's improved anything. If I could get a buyback then I would. I think we're in for some major repairs after warranty expires...
 
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My transmission has been updated twice in my 6000 miles of use. Not sure it's improved anything. If I could get a buyback then I would. I think we're in for some major repairs after warranty expires...
Oh man, really? Was it a software update or did something go wrong with it?

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The first year of a new model can cause fits.
Yes you're right! I've always waited and never bought first year models for the exact reason. Unfortunately this time, we weren't in a position to wait and needed the vehicle sooner than expected. I hope these problems get sorted out quickly [emoji1431]

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TheEnder

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I agree with you on the "relearning"for most vehicles, but what I don't understand is we got the Tahoe with 20 miles on it and it was shifting just fine. What I'm trying to say is was it programmed like that from the factory and didn't have to learn our driving habits, or was it trans already starting to slip from the gate? I'm torn on what to believe here. Although I wanted to test out the power of the 6.2, I couldn't because of the break-in period, but even driving normal it didn't shift hard like it does now.
To your point on the fluid, I chuckled when he said better fluid and then I forgot to ask what he meant, but I think I'm going to call back and ask what he meant by that. Thank you!

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I know this is an old post, but i need to bring this up, as i used to be a Chrysler tech, i know, Chrysler isn’t GM, but the relearns are the exact same with how they work.

Essentially, all newer fully electronic automatic transmissions need a quicklearn after a major component in the transmission is replaced for the transmission to adapt and relearn how to use said component. I don’t know anything about newer Chevy automatics, but i know they share similarities between the Chrysler 8 speed with how fully electronic they are.

Your vehicle when it had 20mi on it didn’t have enough time for the transmission to break in, and that’s why it didn’t shift weird new. Once it has 700mi it’s already broken in or close to it, and by then the clutches have worn down just enough and the TCM has learned what it needs to to shift properly and provide a smooth shift into whatever gear without causing an issue for the driver.

Your vehicle was never slipping, if the valve body went bad then it went bad. I don’t know how it could’ve gone bad, maybe thin metal, maybe crappy design, who knows. But, what could’ve happened is that the TCM was trying to over-compensate for the loss of apply pressure and that made your CVI (clutch volume index) shoot through the roof which is why it would “shift hard” from 1-2.

Correct me if i’m wrong, but this is what makes the most sense to me.


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