2021 Tahoe HC Transmission failure @600miles

[OR VietVet]

The first year of a new model can cause fits.

 

[TAHOEpeful]

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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[TAHOEpeful]

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]

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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