i have a 11 escalade and she is mad at me. Service side blind zone alert system, SERVICE STABILITRAK, SERVICE TRACTION CONTROL are all flashing, about 1.5 months ago we had the fuse box replaced. so far I replaced a few grounds but nothing fixed it yet. I drove it really quick too and she shifts way hard, I was way eazy on the gas. right im working so this was quick dig into it before work the last 2 days. I will mess with her when im off shift on Tuesday . I got to order a tech 2 but haven't yet this might make that happen asap. this sucks hahah been watching youtube for pointers
We have a 2010 GMC Yukon XL Denali with 6.2L AWD with almost 160K miles - a similar vehicle. We experienced many of the same problems about 25,000 miles ago, and in typical fashion, when I took it to the dealer, it wouldn't act up. I started to notice a pattern of when the systems you mentioned would start flashing, the radio going dark, and the engine & transmission basically becoming unresponsive while driving). I took it back to the dealer and had their chief mechanic go for a ride with me, and sure enough, it acted up with him in the car! It turned out to be a main computer problem which, as I now understand, has been a fairly common problem with these '07-'14 trucks. Now, that said, separately, we have also had fairly hard down shifting from time to time, at least that's what it felt like. It turned out it wasn't a transmission issue, but rather, engine mount issues - another very common problem with these same year range trucks. So my guess is at a minimum, you likely have a main computer problem. You may also have one or more broken engine mounts that need to be replaced. Hope this helps, and good luck!