HollywoodBall

You were close! It was actually a "loose" fuse terminal in that box, according to them. Specifically the fuse in the starting/ECM cycle. They replaced the entire unit and reprogrammed the ECM.

I feel like they did. The saving grace was having the failure repeat itself at the dealer. It's been in 3 or 4 times at the same dealer and another in Pittsburgh and each time was lazily and half-ass looked into each time. I opened a case with GMC Customer Care and that seemed to light a fire under everyone's ass to resolve it. The written diagnosis seems thorough and accurate and it hasn't repeated itself, but I often park in my heated garage. So we'll see, but I feel good about it for the first time.

See invoice for dealer tech diagnosis. Entire under hood fuse block was replaced. Sounds like there was a loose fuse connection in the start/run circuit. I’m 75% confident they got it, as it repeated the failure the morning they moved it from parking lot to shop (I delivered the night before so it would sit in the cold. Voila, it replicated for them).

Dude it's the tires. 100%. I put a set of Trail Boss wheels and Tires on my 2019 Tahoe. Loud as ******. Didn't really pay much attention to it until I replaced them and then my thought was "Why did I put up with those garbage-ass tires for so long?" They suck.

2021 Sierra Elevation 3.0 Duramax with just under 50K miles currently. This issue has been plaguing me over a year/year and half and 20K miles. Tends to happen in cold temperatures and always starts with a failed remote start. Remote start fails and upon entering vehicle to push button start, the dash lights up and every single warning message in the system pops up, one after another. It's always happened in colder weather. It left me stranded an hour and half away from home last winter, requiring a tow to GMC dealer and car rental to get home, and back to servicing dealer. That dealer lazily misdiagnosed it as a bad battery. Replaced battery under warranty and sent me home only for it to happen again a few weeks later. Then local deal diagnosed it as a bad engine harness, which of course was on backorder. It took awhile for that to come in and ever since it did the dealer's been dodging the repair. I had it in for an oil change last week and brought it up at checkin or checkout, due to being concerned about cold weather again but the service employee deferred to "my" service rep, who was on vacation, and said he's call Monday. Well sure enough, it left me stranded without a vehicle this morning. Video attached. I have a hard time reconciling a wiring harness issue with cold weather, but what do I know? Any thoughts from the masses? Here's the video of what it does. It eventually starts with CEL, but that CEL clears after a few cycles. Went to another dealer today begging them to just pull the code for future diagnosis and they basically said not possible, but we can check it out in 3 weeks. I've escalated to GM and opened a ticket with corporate.