At 40mph loud bang felt like we were rear ended, sounded like we were rear ended, huge jolt forward nearly causing accident, possible back injury, seats jolted, looked behind us and nothing there. Was driving at 30-35mph and just accelerated slightly to pass a car when this happened. City street 3 lanes. Dealer turned us away because could not duplicate for them. GMC said case was accelerated no call back as of yet.

- Elk Grove, CA, USA

Transmission has shudder and now wont downshift properly while driving

- Lewis Center, OH, USA

Document id 4605342 #16-na-361 : information on transmission harsh 1-2 shift upon first start up/shift of the day under light throttle this GM bulletin was issued Jul 21, 2017 on numerous vehicles and according to this bulletin the problem does not have a resolution. The bulletin clearly states changing the entire transmission will not solve this issue. This is affecting my GMC with the 8 speed transmission. GM has known about this issue but has none the less sold the vehicles to consumers without disclosure. Neither GM or darrel waltrip GMC in franklin tn disclosed this issue prior to the sale. The service dept at the dealer admitted the issue cannot be repaired and told me GM is unwilling to do a trade assistance or buyback. GM claims nothing is wrong with my car yet has a clear document that says otherwise.

- Murfreesboro, TN, USA

While the truck is in motion and when accelerating around 15-20 mph the transmission will sometimes "hunt" for a gear causing the truck to not accelerate. This results in a mild jerking of the truck when it is trying to accelerate and feels like the transmission is slipping/skipping. This is more apparent when going up a grade versus on a flat surface. So I have to push harder on the gas pedal waiting for the truck to shift. This is a safety issue since when not properly accelerating into traffic, an accident is more likely to occur. I see that this issue has already been reported in another incident on your website. I have had this issue since I bought the truck on 02/2018 and the reason I have waited to report is due to the dealer stating to allow the computer to update/learn your driving habits. I have 11,000 miles on the truck now and still experiencing the issue.

- Stevensville, MD, USA

Extremely hard shifting on lower gears. When slowing when it goes from 2nd to 1st it feels like I got rear-ended. Not all the time but once a day at least. It also shudders when slowly accelerating in traffic, sometimes the RPM goes way high and it lurches forward when it upshifts.

- Fort Walton Beach, FL, USA

Brand new 2018 Sierra 1500 Z71. When driving the truck for the first time after sitting for a number of hours (6+hrs) the truck experiences a "hard" 1-2 shift. This occurs 100% of the time when I leave for work in the morning. Sometimes it feels like the transmission slipped, this is the hard shift feeling. Other times the truck loses acceleration, cuts out, feels like the truck has ran out of fuel. Only happens when the truck has been sitting for a long period. When I took the truck in to have this looked into I was told this is a known issue without a resolution. Ive attached a scan'd copy of the document they gave me #16-na-361.

- Gilbert, AZ, USA

Since day 1 of purchasing new, to current date, there is vibration at idle. There is vibration at highway speeds of 60 mph plus. It has been to the dealer 5 times for testing. This is a known problem with thousands of vehicles. GM says it meets their specifications. The dealer balanced the tires 3 times, no luck. The dealer replaced the tires, same issue. I am told the vibration at idle is normal. This problem is distracting when driving. I have been dealing with GM and the dealer for 7 months with no resolve. Https://www.kshb.com/news/local-news/investigations/general-motors-customers-frustrated-over-shaking-in-pickup-trucks this link of a news clip shows what is happening to my vehicle. This happens every day, so ignore the date I entered below. I have videos but the file is too large to download.

- Mansfield, MA, USA