My transmission is failing.

[Xsbank]

When I stuck it in gear after having not used it for 5 days, nothing happened until I stuck it in selectable Low (L1) and it moved off. Then I reselected drive and it’s been OK.
I had also noticed when I was leaving my parking spot with virtually no pedal pressed because we have a 15 km limit, it would suddenly jump as if I had poked the throttle. Now I think it was getting into a gear.
20,000 km Yukon Denali.

 

[Fless]

How's the fluid level? Checking it per the owner's manual?

 

[CMoore711]

8l90 (8 speed) or 6l90 (6 speed)?

 

[lbenson]

8l90 (8 speed) or 6l90 (6 speed)?

If he's got a 2020 Denali like it says below his post, he's got the 10 speed. Odd to hear of it failing, I have yet to come across anyone with a failed 10 speed as there are not enough high mileage examples (or at least that we have heard of). But if he's only got about 12k miles on it he may have just gotten a bad one to start with.

 

[CMoore711]

Touché @lbenson no one’s signatures ever appear when viewing the forum from my iPhone.

I do agree with your assessment of the 10 speed. Have read about random issues but yet to hear of a failing 10 speed.

 

[Rocket Man]

Touché @lbenson no one’s signatures ever appear when viewing the forum from my iPhone.

I do agree with your assessment of the 10 speed. Have read about random issues but yet to hear of a failing 10 speed.

The sigs appear if you rotate your iPhone to landscape mode.

 

[Xsbank]

It’s not in my signature, I wrote what it was in the text.

The dealer suspects the torque converter and it’s booked in next week for a visit with the “transmission specialist” there. I’ll let you know what I find. It came out of a service/oil change about 10 days ago so presumably the fluid level was checked with the scanner? To be honest, I don’t even know if there is a dipstick for the trans as I haven’t looked but I’m off to read the manual.

 

[Rocket Man]

It’s not in my signature, I wrote what it was in the text.

The dealer suspects the torque converter and it’s booked in next week for a visit with the “transmission specialist” there. I’ll let you know what I find. It came out of a service/oil change about 10 days ago so presumably the fluid level was checked with the scanner? To be honest, I don’t even know if there is a dipstick for the trans as I haven’t looked but I’m off to read the manual.

Your signature does say 2020 Yukon Denali, Summit White. So, like @lbenson said, you have the 10 speed.

 

[OR VietVet]

Basics first. Respond back with fluid level and condition checks

 

[Xsbank]

I will let you know what the dealer says, apparently there are no user-serviceable checks on the 10 speed Except for codes.