2018 GMC Sierra 1500

8 speed transmission jerking, the torque convertor has been replaced 1 time already and having same issues as before. This time while in parking lot at store, was pulling into parking space, truck lundge forward during hard downshift hitting cart of person walking in front of truck. No damage and luckly barely hit the cart and not the person. I have also had the truck lunge forward when parking in my garage and hitting the garage wall in front. My truck is back at dealer again after hitting the cart in the parking lot. The 8 speed transmission issue from GM is a safety issue. My truck has already had first torque converter replaced and now having same issue with the new torque convertor

The contact owns a 2018 GMC Sierra 1500. The contact stated while driving 50 MPH, the vehicle started shaking and vibrating abnormally. There was no warning light illuminated. The vehicle was taken to the dealer to be diagnosed. The contact was informed that the transmission oil needed to be flushed. The vehicle was not repaired. The manufacturer was not contacted. The failure mileage was 71,000.

The contact owns a 2018 GMC Sierra 1500. The contact stated that while driving at an undetermined speed, the vehicle was shaking while shifting gears. The contact stated while shifting from four cylinders to eight cylinders, the rear-end was shaking violently. The hood latch warning light was illuminated. The vehicle was taken to the local dealer where it was diagnosed and determined that the tires needed to be replaced. The tires were replaced three times however, the failure persisted. The manufacturer was not contacted. The failure mileage was approximately 50,000.

Experienced heavy vibration or shudder through transmission once fluid got to around 145 degrees. Also transmission has rough shift on the first shift of a drive cycle. When I started to research I found many of the same issues reported with 8 speed transmissions. I’ve also read about the issues with the lifters not working for the active fuel management system though I haven’t experienced that yet. The replaced my transmission fluid at the dealership under the powertrain warranty. This issue showed up at around 35,000 miles, so I am very worried about the safety and reliability of this engine and transmission.

Transmission System, hard shifts and shaking causing vehicle to down shift hard and throw itself forward almost causing an accident when coming to a stop, when vehicle was taken into service they did not diagnose the vehicle for this problem, while driving vehicle shifted down so hard causing vehicle to be stuck in only 1st gear and would not shift out of 1st gear

Transmission slams into gear in drive and reverse while driving it will slam into gear. And occasionally at speeds under 5 going up a hill it will have no power and struggle. I have 59000 miles on it last year around 53000 miles they did a transmission flush and that fixed it for about 9 months. Just took it back in they reprogrammed the transmission and it no longer slams In drive and reverse but still knocks back-and-forth while driving.

I have a 2018 GMC Sierra Denali. I started having problems with the 8-speed transmission at 18,000 miles. The vehicle has been to the dealership for a transmission fluid flush, a transmission relearn, a 5-week valve body replacement, two more trips to the dealership where the truck did not malfunction for them. I have had issues with an air leak on the driver side front door as well. That issue has not been resolved as well. I spent over $60,000 for the truck and have had nothing but problems. I have brought it to General Motors attention and all I would do is get a run around and no results. I was told that there is nothing more that they can do. I am beside myself and just sick as I do not know what to do. I bought a brand new vehicle in order to not have problems compared to a used one.