Truck would slip out of gear while in DRIVE in very dangerous situations. Tuck would suddenly jerk forward when in Drive and Stopped at a Stop Sign or light. No warning light or codes. Transmission Specialist evaluated and determined that Transmission was about to have a critical failure. The 6L80 transmission was replaced with 109,933 original miles on it.

- Essex Jct, VT, USA

The contact owns a 2017 GMC Sierra 1500. The contact stated that while driving at various speeds, the vehicle hesitated while accelerating. The vehicle was taken to the local dealer who replaced the spark plugs, but the failure persisted. The contact stated that on another occasion while driving at an undisclosed speed, the vehicle lost motive power and stalled. The vehicle was later towed to the local dealer who determined that the transmission was faulty and needed to be replaced. The transmission was replaced, and the vehicle was repaired. The manufacturer was notified of the failure, but no assistance was offered. The failure mileage was 110,000.

- Sandston, VA, USA

The contact owns a 2017 GMC Sierra 1500. The contact stated that while driving at various speeds, the vehicle was jerking, and hesitating, and the transmission unexpectedly shifted out of gear while driving. The vehicle was towed to the local mechanic, who diagnosed the vehicle and determined that the torque converter, transmission pump assembly, and reverse clutch were faulty, and needed to be replaced. The vehicle was not yet repaired. The manufacturer and local dealer were notified of the failure, but no assistance was offered. The failure mileage was 50,000. The VIN was not available.

- East Haven, VT, USA

The automatic transmission occasionally slips and slams hard into gear between first and second gears, causing the truck to lunge forward when attempting to stop. This could potentially cause the truck to hit another person or vehicle when attempting to stop. This problem was immediately observed upon receiving the new truck in 2017 and is ocurring more frequently over time. The problem was reported to and taken in to the GMC dealer. They advised that they were unable to reproduce the problem during their time with the truck. There have been no safety incidents thus far. No warning lamps or messages have been displayed on the dashboard.

- Reno, NV, USA

8L90 transmission shudders and jolts forward at low speeds. Delayed acceleration when accelerating from a stop.

- Emporia, KS, USA

The contact owns a 2017 GMC Sierra 1500. The contact stated while driving at various speeds, the vehicle hesitated and shuddered upon depression of the accelerator pedal with the check engine warning light illuminated. The vehicle was initially taken to a dealer where the dealer found no defects with the vehicle. The contact was then informed that the shuddering was normal operation. The vehicle was then taken to an independent mechanic and the mechanic discovered a defect with the bell housing. The vehicle was not repaired. The manufacturer was notified of the failure. The failure mileage was approximately 29,000.

- Bamberg, SC, USA

Transmission making a shuttering feeling while driving. Felt in the steering wheel. Dealer said it-??s not covered unless still under powertrain warranty. No check engine light while happening. There was a pending code about transmissions control module.

- Pittsburgh, PA, USA

The transmission isn't working properly and there is a major delay (over one year) in parts because so many are needed.

- Wilmington , NC, USA

The contact owns a 2017 GMC Sierra 1500. The contact stated while driving at an undisclosed speed, there was an abnormal sound coming from underneath the vehicle, after which the vehicle lost motive power. The contact was able to continue driving to the destination. The check engine warning light was illuminated. The vehicle was taken to the dealer, who diagnosed a failure with the torque converter. The vehicle was repaired; however, the failure reoccurred 2-months later. The manufacturer was not notified of the failure. The failure mileage was 76,000.

- Loda, IL, USA

8 speed transmission shudder reported by GMC for my model. My truck has 35,500 miles and has the shudder posted in a technical service bulletin by GM. The supposed fix is x 20 quart fluid flush, new filter, and flash the computer. GM will not cover under any warranty as they say this is a -??fluid change-?? even though the manual says this fluid should not be changed until 72,000 miles. The dealerships act like they are just hearing about this which is a total lie. They were told over a year ago if they had any new on lot to change the transmission fluid to mobile one synthetic before selling them. This should be a recall as GM knew this was an issue during manufacture. This is a $1200 repair that should be covered by GM.

- Hernando, MS, USA

#1 While merging onto the highway, the vehicle began to shake violently and have a sudden lose of power due to a misfire on cylinder 6 and 4. I was unable to merge onto the highway as the vehicle would not accelerate almost causing me to be hit from behind. I was able to get the vehicle off to the shoulder to avoid an accident as it was barely able to stay running and the CEL was flashing. The failed parts (AFM lifters/push rods and VLOM) have been removed from the engine and saved for review. #2 My family's safety was put at risk as the vehicle had a sudden lose of acceleration while trying to merge on the highway almost causing us to be hit from behind. #3 I spoke with my local GMC dealer and explained the situation and diagnosis that I have completed on the vehicle. That wanted me to pay out of pocket to tow the vehicle in and would not cover anything as the vehicle is barley out of powertrain warranty (72695 miles). I have been an engineer in the automotive industry for almost 10 years and can properly diagnose a vehicle and the issue it has. Trouble codes were provided along with pictures and videos as evidence. I understand when something is a safety issue and needs to be addressed as this is a common issue with GM 5.3l and 6.2l engines. I then spoke to GM corporate (Mandy, case# 9-12424996557) and once again they wanted me to pay for everything out of pocket even though this is clearly a safety concern with their product and the diagnosis had already been completed. This vehicle has all the maintenance records since it rolled off the showroom floor, proving that the failure is not related to neglect or poor maintenance of the vehicle. There is very clearly a design issue or manufacturing issue on this components. #4 Components are available for inspection by mfg. #5 There were not warning lights or any other indicators prior to the failure. Oil pressure was at 40PSI and engine temp was ~200F. All within the normal operating windows of the vehicle.

- Belmont , OH, USA

Experienced hard shifting in my transmission a couple before it all of the sudden it made a thing noise and didn-??t want to move forward to easy. Babied it home and by then it was whining and whistling all the time. I Quit driving it immediately and had it towed. Being only a 2017 I can-??t believe this happened. Plus I had a 2014 prior to this and I had the same issue but traded it off before it went all the way out. After going to social media I am finding out that so many people with mid to late model 2000s have had this same issue, even family. Plus I was told by 2 different transmission places this is very common in these with Chevy and GMC model trucks. How could this be going on? I am assuming because people don-??t know to report. Being on disability and a fixed income this took a hit to my bank account, actually a home equity loan.

- Finger, TN, USA

The vehicle would shudder when trying to accelerate. I almost was hit by a semi truck trying to merge onto the freeway. Made an appointment with the mechanic then a couple days later I was at a stop sign and the vehicle would not accelerate at all. I placed in park the tried shifting back into drive and still nothing. I had to turn the vehicle on and off twice before I was able to shift it in drive an it actully would accelerate. Even then it would shudder and not accelerate fully. Very dangerous. Just hit 100k miles. GMC Certified Mechanic said the transmission is shot and needs to be replaced. Cost to replace over $6,000 Bought the truck in 2020 for $35,500 and just paid it off.

- Redding, CA, USA

Transmission shifting hard. Shuddering around 60-65 mph

- Hampton, AR, USA

I purchased the vehicle in November or December 2022. Since then I-??ve had problems with my transmission. The torque converter was replaced 2 times, it-??s been in the shop 5-6 times and nothing fixed under the warranty when I purchased it. Finally the dealer I purchased from said they won-??t take the vehicle back and won-??t spend any more money on fixing the truck. Now it has become on my dime to figure it out since I gave up trying to have a shop diagnose and fix it. The last shop said I would have to pay to have the transmission removed and possibly have the valve body replaced since the dealer I purchased it from gave the second shop one chance to get it right. The transmission downshifts hard and clunks since the first day of purchase. Makes a weird wining noise still til this day. I have spoken with the owners of the dealership and they did not seem to care about my problem.

- Hamden, CT, USA

Truck has always shifted rough, now with only has 102,000 miles has been serviced regularly exclusively at the dealership. It started slipping gears and I was just informed by the dealer that the torque converter detonated and the entire transmission must be replaced.

- Mount Olive , IL, USA

The transmission is shuddering, hard shifting, shuddering and lunging into gear. It is the 6L80 transmission Also has little to no power, took it to the dealership for diagnosis and they say the transmission is bad, torque converter is also bad sending metal throughout the rest of the transmission.

- Reeds Spring , MO, USA

Transmission temperature sensor has failed. It is available for internal inspection within the transmission pan. Safety has not been in issue, but, apparently it can cause hard shifting when the sensor starts to go bad. You can also easily tell when the sensor is going bad by watching your trans fluid temp needle. It will erratically bounce up and down, sometimes slightly and other times it's big jumps, so you will not be able to tell if the transmission is overheating or running at normal operating temperature. The problem has been confirmed by a local service center. The vehicle/component has not been inspected. There has not been any problems prior to this issue. The check engine light came on 1/24/24 in the evening time. Check engine codes are P0711 & P0700. This is a known issue between 2015-2018 GM vehicle equipped with the 6.2L & 8-speed transmission. There is/was a special warranty number, #N192291660, that qualifies with the 2016 models.

- Saint Augustine, FL, USA

I was driving my truck home from work, when all the sudden the car at a stop sign lurch forward, with the brake applied and was not moving, or I would have hit the car in front of me. Upon, the green light, truck started to shift and go faster, while making a whining noise, at only 26 miles per hour, then, the vehicle, tried to speed up with nothing engaging, and came to a complete stop very aggressively and abruptly, while in traffic, I almost was hit from the sudden stop. Getting to the side of the road, the truck wouldn-??t move anymore, and except in rear gear. Called OnStar service and vehicle was towed to the closest GM dealership, about a mile from my house. This was on a Saturday evening, On Monday, the dealer service agent called me, had already diagnosed the problem as a failed 6L80 GM transmission, this was at 930am, asked if I wanted it repaired I said yes. The dealer called back at 3pm that same day and said the transmission had already been repaired. Which to me is a bit surprising as it needed a new transmission, which should take longer. Glad it was fixed so fast. The cost was to be around 6700 dollars. From my knowledge this is a known issue with these transmissions. My concern, is that I could have been in an accident from a known defect in manufacturing that GM knew about and did nothing to address.

- Butler, PA, USA

Transmission has stalled many times from shifting through 1st and 2nd gear going across divided highways and nearly causing accidents, also it has a very bad shudder and hard shifting.

- Cocoa , FL, USA