2019 Denali Shifter Issues

G-Z-M · February 7

Hello everyone. I know this topic has been covered in a lot of posts, YouTube videos, and Google articles—and yes, I’ve gone through quite a few of them—but I haven’t found anything that quite matches what I’m experiencing. So here goes.

I recently purchased a 2019 GMC Denali 1500, 6.2L, 10-speed, with 180k miles. The only reason I was comfortable buying it with that mileage is because it was a one-owner truck, and I verified through the selling GMC dealer that they were the only ones who ever serviced it, with records to back that up. It actually has a really clean service record with nothing major ever reported. Overall, the truck looks and drives like it’s nearly brand new, with an exception as I am explaining below.

As I’ve gotten more familiar with it, I’ve noticed that when taking off from a stop—mostly when cold—there’s a noticeable delay when it shifts from 3rd to 4th gear. It’s about a half-second to one-second pause that almost feels like a slip, followed by a fairly firm shift. Once past that point, the rest of the gears seem to shift somewhat normally. When the truck is warmed up, it still does it, but it’s much less noticeable. One other thing to note, when I accelerate a little more aggressively, the shifting is slightly better. I don't mean stomping on it, just taking off and holding my RPM's firm throughout the gears. The slip-bang is not as bad.

I contacted the GMC dealer who sold and serviced the truck its entire life. They confirmed the previous owner had a transmission flush and fill done at around 100k miles. I’m hoping the transmission itself is mechanically sound, but I’m unsure what could be causing this behavior.

I really don’t want to take it to the dealer just to pay $150+ for them to tell me “everything is normal.”

Does anyone have any specific DIY checks or things I can try? Or is this just typical behavior for these trucks?

Thanks in advance.

1660.heic

Edited February 22 by G-Z-M

JimCost2014 · February 12

If it has only had 1 transmission service in 180,000 miles, I would say it is well overdue. I would start there and see if it makes a difference.

GMCustomerService · February 23

We're saddened to hear of any shifting challenges you're experiencing with your 2019 Denali. We want to connect further so we can explore potential ways we can assist in resolving this matter alongside your dealer's support. To do so, please follow up with us via email including your VIN, full contact information, current mileage and the name/location of your servicing dealership. Furthermore, be sure to include your Username and Forum in the subject line. Your cooperation is appreciated. By sending us a message, you consent to the information you provide being monitored and recorded by GM or those acting on GM’s behalf, subject to the GM Privacy Statement: https://www.gm.com/privacy-statement.