Jay P

There is a switch on the dash to shut it off. The only bad part is it resets when you shut the truck off. Jay

There is a switch on the dash to shut it off. The only bad part is it resets when you shut the truck off. Jay

You need a relearn tool. Changing tire pressure doesn't work on the newer trucks.

I have no issues with my 2019 Denali connecting to my iPhone 11 pro or my Samsung S10E. I agree it's time for a dealer visit. Jay

The TSB doesn't say anything about where the truck is assembled only where they are sold. As far as I know the 8L90 is only produced in Toledo, Ohio.

March 1st 2019 is the cutoff date for the factory fill with new fluid. MC-10163241-9999.pdf

It turns back on at 35mph no matter what. If you have a low range transfer case it may stay off but your speed would be limited. Jay

Take it for a drive and get it above 40mph and then go home and try to learn the sensors to the truck. Jay

The Range unit does both. The old non beta unit would work to disable AFM and the auto stop/start (most recent version). The new beta unit adds the DFM disable. When Range was still a small company based out of Colorado they had a unit meant for fleet use that would only disable the auto start/stop. Not sure if you can still gewt that after they were bought out at the end of last year. Jay

TSB -> 19-NA-121 for 8L90 in T1 trucks. It only applies if your truck was built prior to March 1st 2019. After that date the trans already has the updated fluid. Jay MC-10163241-9999.pdf

The only time I have an issue is when it's snowing and the roads are sloppy/slushy. It has something to do with ice coating or hanging on something. As soon as I get up to highway speed (stuff warms up) or all the stuff melts out from under the truck the issue is gone and the 4wd light is back to normal color. Unless the TCCM is somewhere it can get ice on it thats not the problem. Jay

Ogden Utah. Came UPS. Jay

I agree with the sensor theory. I only have issues when there is a lot of road spay from the melting snow and temps below 25. Once I get up to highway speed the problem clears and the 4wd indicator goes back to white and the service 4wd goes out so ice buildup makes sense. Jay

Do you know which sensor?

Before you do anything take the truck out on the highway and get it up to at least 60mph. The sensors are shipped from the factory in a sleeping state to preserve the batteries prior to use. Then put the truck in TPMS learn mode and try again with the tool. I had to do this with my 2019 when I put winter tire and new rims on my truck I got from Tire Rack. The info was given to me by a service manager friend from a Chevy dealer in Minnesota. He said it's a common problem with new sensors. Most of the time spin balancing will wake up the sensors but not always. Jay