2021 Yukon Denali hard shift in Auto

[Nautilus571]

I own a '21 Yukon Denali with 50k miles. We just bought it about a month ago. All is fine until I place it in Auto mode. It hard shifts 1-2, 2-3, and 3-4. It is like a thunk and is clearly felt and audible. I tried each of the other modes, 2WD, and 4WD. This issue is not present in either of them. Shifts fine. I also tried Auto in Sport, Touring, Tow, and Off-road. Same issue in Auto. Any ideas? Oh, and took it to the dealer. They reset the tranny electronics and said to drive it easy for 200-300 miles so it can relearn our driving style. Was fine for about 150 miles then it started again.

 

[mb1500]

Do you typically drive in Auto?

 

[Nautilus571]

Yep... and just read a thread that Auto should only be used in foul weather. SMH. Although, I do have better control in Auto. It gets a little squirrely in 2WD.

 

[John52269]

There is a delay when in auto 4wd. Put in 2wd and enjoy your drive again. Trust me.

 

[mb1500]

Yep... and just read a thread that Auto should only be used in foul weather. SMH. Although, I do have better control in Auto. It gets a little squirrely in 2WD.

Try changing the fluid out. 50k the fluid is probably toast, does not have much capacity.

Auto does add minimal wear over time but does not cause damage like 4wdHI on dry pavement would.

 

[Nautilus571]

Try changing the fluid out. 50k the fluid is probably toast, does not have much capacity.

Auto does add minimal wear over time but does not cause damage like 4wdHI on dry pavement would.

In the transfer case, correct?

 

[StephenPT]

In the transfer case, correct?

Yes - the clutch packs are partially applied and ready to engage when extra traction is needed. This will increase wear on your transfer case and require more frequent oil changes.

Transfer Case - 1.6qts - GM # 88865601 (Dexron VI)

 

[jepaul2198]

I own a '21 Yukon Denali with 50k miles. We just bought it about a month ago. All is fine until I place it in Auto mode. It hard shifts 1-2, 2-3, and 3-4. It is like a thunk and is clearly felt and audible. I tried each of the other modes, 2WD, and 4WD. This issue is not present in either of them. Shifts fine. I also tried Auto in Sport, Touring, Tow, and Off-road. Same issue in Auto. Any ideas? Oh, and took it to the dealer. They reset the tranny electronics and said to drive it easy for 200-300 miles so it can relearn our driving style. Was fine for about 150 miles then it started again.

2021 Denali - Vehicle Knock, Stutters, Surges, Rough Acceleration - In Auto Mode, After Lifting Rods Replaced

Hello, Apologies ahead of time for my first post being what it is. I'll try hard for brevity, but often my posts are long because I do not have time to make them short. I'm not a mechanic and can barely change al alternator on a 1993 K5 Blazer, I'll do the best I can. 2021 Yukon Denali...

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