I don't know how I missed your replay earlier, sometimes it's hard to read everything on my phone. Thank you very much for the suggestions. I actually have the updated bypass valve which I bought about this time last year, but did not install it because I didn't want to do anything the dealer could argue I voided the warranty. I think it is a great idea to look for an independent shop for future out of warranty work and will look around my area for one.Just going to add a recommendation I just made in another post especially on the bypass valve, cooler and pan to keep your trans cool. My torque converter blew on Christmas Eve on my 2018 at 65k miles, shed a ton of glitter into the fluid and ended up turning into a reman transmission after having AAA tow it nearly 300 miles home. Luckily I felt the hesitation/slip/flare shifting and saw the temp rise and pulled it off the road. I have the Range AFM disabler adapter too and was checking to see if that had anything to do with it but discovered that was not likely.
"transmission hot idle engine" message alert setting
Thanks Rygrego, and all, ODB code came back with a failed transmission fluid cooler thermostatic valve. One valve ($131) and three seals ($10) fixed my issue & yes I replaced the fluid, filter and pan. Display now reads between 149 - 182 for Transmission Fluid temp Thanks for the help on this...www.tahoeyukonforum.com
The issue though unfortunately here is since you are already at the dealer (which can't blame as you are still in warranty) you are stuck with their runaround and also OEM parts with all of their flaws. Most good aftermarket transmissions come with a billet converter cover which addresses the design flaws of OEM with it distorting around where the three fittings are welded to the plate. I would insist if nothing else while at the dealer and if they are already into it they do replace the converter anyway with all of the fluid AND install the updated thermal bypass valve that opens at 158F to keep the temps down per their own TSBs recommending that happen with any transmission work and then once you get the truck back consider at least a transmission cooler now, aluminum pan when you do fluid again next time (this is probably excessive but I do my fluid every year but I also get away with that process easier as I don't need to do the filter as often given the pan drain plug). You might not need the Surecool kit if you get the updated thermal bypass but mine runs in the high 120s F on the highway, 130-135 in town.
With Auto 4WD I would suggest keep it out of there. Consider just shifting to 4 High if you are getting into snow or ice conditions but obviously not on dry pavement. Given your mileage and the nature of what they already need to do I would suggest have them do the transfer case fluid (If not already when dropping the trans). Your differentials too while they have it IF the price to do so is not more than comparable independent shops.
This is just from personal experience - I actually stopped using dealers years ago especially with the runaround, money grab tactics and poor/overpriced repairs on all three of my GM trucks, one of which could have turned into a fire with one of those repairs being oil cooler lines not installed properly. Before your warranty expires I would advise find a really good independent shop near you and develop a good relationship. That will go a long way to keeping your truck on the road and the costs and frustration of doing so much more tolerable.
Good luck and hope everything works out for you either way you proceed.
As far as the auto 4WD, this is my wife's daily driver and she drives about a mile to work and back. The day before we brought it in, the roads were very slushy so she turned it on. She forgot to turn it off before dropping it off at the dealer, but in no way is the vehicle run with it on very often. I just hate that it gave them another excuse for what could be the problem even though I rarely drive with it in auto 4WD and I'm the one that noticed the shutter.
Thank you for all the responses, I appreciate it.
