I’m glad to see this question asked already. I am currently experiencing the same difficulties with my 2017 Yukon, XL SLT. Mine is very intermittent though. It may go to months and not have an issue. Usually when it will not start, I disconnect the positive battery cable let it sit for 15 minutes, reconnect, edit fires, right up and charges fine. Occasionally, I will notice that the truck is not charging, this usually happens once every month or two. Again, I disconnect the battery, wait 15 min, reconnect, and it fires up and charges. Well today that little treat didn’t work and I had to get a jumpstart when I got home, I left the truck running to check charging system. At the battery, multimeter read 13.5 to 14.2, but was fluctuating back-and-forth pretty quickly. When I saw the truck off and measured battery voltage, it was at 12.5. When I went to start the mtruck again, nothing, only a click. So I sat here looking through the forum trying to see if anyone else had similar issues. After about five minutes, I tried to start it for the hell of it and it fired right up. Turned it off, wouldn’t start back up. This truck has a six month old alternator, six month old battery and has been the only issues I’ve had with it since last January, when I bought it. Any additional help here it would be greatly appreciated. Starters start out around 300 bucks around here and I really don’t want to spend that. If not absolutely necessary. Thank you guys, look forward to hearing your suggestions