UllUllColl

Issues as well, Range AFM WORKED fine for a few months in my 2017 GMC Sierra w/ 6L80 transmission, the mileage was fine, drove fine. about a month ago, my transmission acted up, wouldn't shift, over heated the transmission. Now I was told to unplug the device and plug it in when truck was running. Then it worked again, for a while, now again, I am having shifting issues, truck shifts into high gear too soon, 1,2,3 is ok, then it goes 4th 5th 6th too soon. I will toss this thing and advise against anyone getting one. There are better ways. Cost me a tanny flush and reprogramming (reflash). Pfft. P.O.S. is my opinion!