2024 - Possible Transmission/VB issues..

[The_DJH]

Ahoy! Looking for feedback (yes I also searched) on a few things I’ve noticed over the past 2-3 weeks on my 2024 AT4 3.0 with 66k miles.

1. When outside the vehicle, shifting from park to drive, drive to park, drive to reverse, etc…. it’s damn loud, like a big clunk. Inside the vehicle you can kinda feel it, but not hear it over the engine.

2. When going roughly 25-30 mph and letting off the peddle, the immediate downshifts can be felt, same when starting to accelerate. Once I get above 30ish, I can no longer feel the shifting.

We dealt with valve body issues before on our 2023 Yukon AT4 6.2l and didn’t have these symptoms as above.

Just looking for collective feedback, I do have an appointment on Monday with our dealer to have it looked at.

Thanks!

 

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[R467X]

Have you had your transmission fluid changed? If not, that's where I would start.

 

[The_DJH]

Have you had your transmission fluid changed? If not, that's where I would start.

I bought the vehicle with 55k on it and I have not done that.

The service associate said they would check it out, but might lead to that service needing to be done.

Thank you!

 

[R467X]

I bought the vehicle with 55k on it and I have not done that.

The service associate said they would check it out, but might lead to that service needing to be done.

Thank you!

More than likely - bad valve body. When I got a bad unit from nextgen and tried to shift, it would take 3-4 sec for the shifts to take effect followed by a clunk with a jolt and all sorts of lights / 10+ codes when running using a scanner.

These trannies are extremely sensitive and not reliable. Realistically you should've been on your second transmission fluid change. I think GM recommended is 35 but I wouldn't push past 25-30k per fluid / filter change.

I don't recommend you drive it anymore. Tow it to the dealer and wait. Otherwise you're risking more damage with possibility of just getting stranded.

 

[The_DJH]

Yup, went through the same thing with our Yukon. Replaced the original, the second one failed within a week, then the next one has been good.

I'm sure they can look at the history and find out if it had the fluid been changed. Currently, I have no lights, but i can run my ODB and scan, see if anything comes up.

 

[R467X]

Yup, went through the same thing with our Yukon. Replaced the original, the second one failed within a week, then the next one has been good.

I'm sure they can look at the history and find out if it had the fluid been changed. Currently, I have no lights, but i can run my ODB and scan, see if anything comes up.

Unless you have an expensive scanner you're unlikely to pick up codes especially if there are no warning lights.

 

[The_DJH]

That's a big negative!