Once upon a time, I had a 2014 GMC Sierra with this seat issue. Took it to the dealer/s many times and was always told either this was normal, or can’t find the problem. I’ve tried all the DIY fixes to no avail. I gave up on the truck and bought a new F-150 and have not looked back, and doubt I ever will. I was a loyal brand customer since 1988 and this experience destroyed that. However, my fight is not completely over, we own a 2015 Yukon Denali and like clockwork, the damn driver’s seat is starting to move just like the Sierra. Precision Engineering the commercial says, makes me want to puke every time it comes on!
Rant Over….