I have a 2015 GMC Sierra 2500HD SLT, I got the same message on my screen and got beeps while driving instead of seat vibrating, took it to dealer and mentioned reading this forum and what was found with a wire under seat. Dealer inspected under my seat and found the wire harness got stuck in the seat track and yanked out a plug. All fixed and thanks to people that post here as it probably saved me a long hassle as dealer said when I brought it in that they never encountered this problem yet.