I was driving down the highway when my vehicle loss control of operation and check engine light came on. After taking it to the GMC dealership it was determined to be a bad lifter in the motor. The garage had to take the motor completely apart to repair a bent rod and cylinder in the motor. There are numerous reports and a pending class action lawsuit concerning this device in the GMC Sierra trucks and other GMC vehicles. The lifters in the cylinder of this motor are designed to switch the engine from V4 to V6 to save on gasoline. My vehicle has been repaired by the GMC garage but I've seen reports of this problem repeatedly happening in these vehicles and it causes me great concern because if there is a lot of traffic in the area I could get hit or cause an accident by not being able to operate the truck. My vehicle is available for inspection upon request. The safety of myself and others is put at risk because the sudden equipment breakdown could cause an accident. The problem was confirmed by the dealer. No other parties have inspected the vehicle. No warning lamps went off prior to this happening and the vehicle is only a 2018 and only has 36,000 miles on it.

- Albright, WV, USA

The contact owns a 2018 GMC Sierra 1500. The contact stated that while driving at various speeds, the vehicle experienced shifting while shifting into a lower gear, causing the vehicle to suddenly lurch forward. The cause of the failure was not determined. The local dealer was notified of the failure but no assistance was offered. The manufacturer was not contacted. The failure mileage was 50,000.

- Franklinton, LA, USA

Transmission shrudder with low mileage

- Willcox, AZ, USA

During down shifting in lower gears while reducing speed, transmission makes a loud noise followed by vehicle hard lounging forward. Occurance is intermittent and unpredictable. In city traffic this has potential to cause an accident because vehicle lounges forward when speed is reduced. Vehicle has 18900 miles. Made in 2017.

- Salt Lake City, UT, USA

Transmission is slamming violently during shifting, transmission fluid is dark and contaminated. Dealer says-" operating as designed, no issue found" also truck shakes and vibrates violently while driving

- Lapeer, MI, USA

Very very bad shudder vibration noticed mostly during light throttle acceleration of 30-64 mph (48-104 km/h) during steady state driving with the transmission not actively shifting gear..

- Palm Coast , FL, USA

The contact owns a 2018 GMC Sierra 1500. The contact stated that upon depressing the accelerator, the vehicle shuddered while upshifting. There was no warning light illuminated. The contact had taken the vehicle to a local dealer where they were unable to service the vehicle. The contact had also taken the vehicle to an independent mechanic who informed him that there was a TSB placed on the vehicle. He explained that the incorrect type of transmission fluid had been placed in the transmission which would cause the failure that he had experienced. The contact then called Sewell Buick GMC of Dallas (7474 Lemmon Ave, Dallas, TX 75209) where he was informed that he would be charged a diagnostic fee prior to the repair. The manufacturer was notified of the failure but offered no assistance. The vehicle was not repaired. The failure mileage was approximately 45,000.

- Dallas, TX, USA

The contact owns a 2018 GMC Sierra 1500. The contact stated while driving at various speeds, the vehicle lost power steering assist causing the steering wheel to become firm. The steering wheel jerked while turning and the vehicle stalled on several occasions almost causing a collision. The vehicle was taken to the dealer and the dealer informed the contact that the failure was related to Technical Service Bulletin 18-NA-161. The vehicle was not repaired. The manufacturer was made aware of the failure. The manufacturer promised to provide a callback. The failure mileage was 47,184.

- Chicago, IL, USA

I have taken my truck to temecula valley Buick GMC on 3 separate occasions after noticing my transmission shifts hard. I have experience clunking shifts both in the up shift and down shift, typically at lower speeds. There are times when the transmission shifts gears it propels the vehicle forward in a jerking fashion, very similar to a rear end fender bender. The last time I took my vehicle to the dealership, I was told that the vehicle is shifting at normal specs and if it keeps acting up, to bring it back when it is more consistent. The vehicle's warranty runs out in a few months.

- Fallbrook, CA, USA

After cold starts when accelerating the transmission slips from 1st to 2nd and throws your body forward. After that first gear change it doesn't do it again until another cold start. Around 34000 miles I am getting a rumbling vibration through the dash and steering wheel when holding speed between 35-75 mph. The RPM guage will jump slightly and it will feel like going over rumble strips. Acceleration is very weak at times. Sometimes its ok. There has to be something done with these torque converters and transmissions by GM. Unacceptable for a 40-50K dollar truck!

- Romeoville, IL, USA

Have been to dealer 3 times transmission ruff/slipping on 1-2 shift

- Springfield, MO, USA

Truck shifts hard from 1st to 2nd gear and vice versa. When down shifting from 2nd to 1st it feels as if you get rear ended by another vehicle. It shifts hard when switching between drive and reverse with an audible "clunk" and jerking on the truck.

- Owensboro, KY, USA

Hesitation when engine is cold shifting from reverse to drive. Some shift is so hard that it feels like being hit from behind. Took truck to dealership to correct the problem. They performed the tsb 18-na-355. This did not correct the problem. Dealership advised there was nothing else they could do about this issue.

- Texarkana, AR, USA

The first thing that happened was that all of the electrical systems on my truck went out and my truck would not start. It finally started but it would not move finally it would move but very slowly this happened on 11/20/2019 I have documentation through onstar for this incident. My brakes started slipping on 07/01/2020 and still do not work properly. My transmission has never shifted correctly. When I accelerate or when I slow down there is a shudder and a jerking sound. After sitting for a while when my truck is put in reverse it hesitates and then seems to jump into gear.

- Owens Cross Roads, AL, USA

The transmission failed at 32,000 miles slipped so bad could hardly drive it home on highway I95 jacksonville Florida. Finally got a dealer appointment after over 2 weeks of waiting without the use the vehicle. They replaced the fluid and said it was now good. Still tends to slip I asked why they were not replacing the whole unit said no need as my warranty is almost up?

- Fernandina Beach, FL, USA

Hard shifting that started around 40000 miles and has progressively gotten worse. The same thing happened to my 2017 Chevrolet Silverado 1500 and at 90000 miles that vehicle's #3 sensor in the transmission failed. It appears this vehicle is on the same path. The transmissions in these vehicles are trash. It happens in lower gears.

- Tomball, TX, USA

I have been noticing a shudder and hard shifting intermittently when driving about 30-60mph and I took it into the shop they said they can not duplicat the issues so I take it back and it started doing it more. I took the truck back to the shop again and yet again they told me they can not duplicate the issue. No here I am at 17K miles on is still doing it and shiftting hard and now there is a knocking noise. I talked to the dealer ship and they said its under warrany still just drive it tell it get worse.

- Anchorage, AK, USA

While under power and driving, the truck experiences noticeable vibrations that seem to come from the drivetrain.

- Burleson, TX, USA

Purchased vehicle brand new from dealership and from day one, I notice the power train slow to shifting from gear one to two. The vehicle hesitates and sometimes shifts hard only during cold starts. Every time I take it in for my schedule service I report the same issue to my service advisor along with the service manager at the GMC dealership. They say that it is a normal problem and they know about it. The last schedule service I told them about the same problem, this time his service tech test drove vehicle and said torque converter was shuddering causing vibration. The solution he said they changed the transmission fluid. Today I still notice the same issue and will report to the dealership next time I take in for service. I have read this is a common problem from the manufacture since putting in an 8 speed transmission. I feel this is a safety issue and some day I may feel that the transmission may lock up on me and may cause an accident.

- Orange Park, FL, USA

When truck is in motion shifting from reverse to first/second gear it jumps forward into gear. There is a hesitation shifting into gear. It is a very well known problem with the 8 speed transmission. I have been in contact with the dealer but 3 different times. The know the problem as does GMC. They actually can fix the problem. But will not do anything until GMC sends out a technical bulletin. There has been an unbelievable amount of complaints. I understand GMC is hesitant because they may have to replace transmission and or torque converter which would naturally cost a lot of money. But also I understand changing to a different transmission fluid will help. But dealer will not do it. This has been going on since the day I bought it brand new and I only have 5700 miles on it. I have not had accident because of this. But concerns me with the hesitation and jumping in to gear. Also it does not do it every single time. Depends on your take off speed.

- Horseheads, NY, USA