The valve body inside the transmission has failed and GM has known it to fail but they have done nothing about it. My vehicle has been in the shop for 2 months because of it and âparts are on back orderâ itâs terrible iâve bought this vehicle in august and itâs constantly been inside the shop for various issues. My transmission lost 7th gear and it came to an immediate stop in the road because of it. tires screeching and all. truly embarrassing that you can spend 83,000$ on a truck and it be such a peice of junk.