Vehicle developed a vibration at 80mph which fades in and out. Tires were road forced balanced, and alignment was done. Transmission fluid was changed. The shacking at 80mph continued. On a 30 mile commute at 80mph the vibration is extreme 25% of the time (like driving over a rumble strip), moderate another 25% of the time, and the other 50% the vibration is not noticeable.

- Boynton Beach, FL, USA

The eight speed automatic transmission stutters and acts like it doesn't know what gear to go into under light to normal acceleration. This occurs while cold and during the warming period, (normally up to around 180 degrees), but tends to resolve after the engine is completely warmed up. This transmission problem is continuous and happens every time after the vehicle sits all night or if it has simply sit for a few hours. It is very apparent, other passengers ask what is wrong with the vehicle when they ride in it. I bought the vehicle new, but when I took the test drive it was already warmed up. Therefore I was unaware of the issues present. I went back to the salesman to describe the problem and was informed this happens with all the 2018 eight speed Silverado's he has driven on their lot. I looked on the internet and found these transmissions have a learn cycle, so I decided to give it some time to see if was a learning curve with the computer. It never cleared up. I later brought the vehicle into the dealership for the initial service and described what had been happening with it to the service department. I left the vehicle overnight so the technician could drive first thing in the morning and perform an services. The next day I was called and told my vehicle was ready. Upon arrival I was informed the technician was able to duplicate the problems I described, but it was normal for the eight speed transmission. However, it becomes worse to bring it back in for further diagnosis. I called GM, they also looked into the case for about a week, then called back and stated that is normal for the transmission. I bought the vehicle new with about 2,500 miles on it, (demo), and have had it only a few months. It currently has less than 10,000 miles on it.

- Columbia, SC, USA

Several times, while driving right around 55 mph, the transmission downshifted for no reason on thruway conditions. When this happened, it was almost like slamming on the brakes quickly. On all occasions, my body lurched forward. If someone was behind me, I probably would have been rear ended. On another occasion, with my son in the truck, we stopped at a red light and the transmission clunked so violently, that we both thought we were rear ended at first. I described the issue to my GM service shop who said that they couldn't find an issue and that the codes were all normal. I was advised that the clunk at the red light was common, as the transmission has to relieve pressure. No way is this normal! I got on line to review forums and it appears this is a very prevalent issue. Yesterday, I lost my transmission completely on a thruway. I heard a loud clunk and the rpms spiked. I left the highway asap but could not go over 30 mph or the rpms would just spike without motion response. Exiting the thruway at this speed was very dangerous! even with hazards on, drivers seldom slow down or move over, especially 18 wheelers. These transmissions are clearly a safety hazard.

- Highland, NY, USA

Constant vibration/shake coming from the vehicle at any speed above 65 mph. The truck has been like this since the day it left the dealership. When on highway and vibration is felt, putting the truck in neutral does not change the vibration, slowing down makes it slightly worse, speeding it makes it slightly better. Feels like there is something seriously wrong with the geometry of the truck making it unsafe to drive at highway speeds. Road force balance was already done and the problem persists on a brand new truck.

- Miami, FL, USA

In May 2018 I purchased a new Chevy Silverado lt Z71 pu. I live in Colorado and when I drive the truck down the I-70 mountain pass the transmission is downshifted beyond what io would call a safe down shift. Im traveling down the pass, just coasting, down hill assist mode is off @ roughly 55 mph the transmission down shift hard. The RPM goes from ~1850 to ~3800 RPM. The engine and transmission and engine both make a lot of noise when this happens. I traveled the pass about 8 time now and the truck does this funny shift everytime and I have picture showing 4 events. I've taking the drive into the dealer and since the computer doesn't log a error code the dealer doesn't know what to do. This past week they gave another 2018 P/U with the same tranny and engine and that truck did not do the same downshift. I believe there is something wrong with my truck and also if this event happened in the winter on a snowy road the truck would spin out of control and cause a accident and is a huge safety concern. I also filed a complaint with GM but they are really not help to resolve this problem. The dealer looked at the truck again today, no codes recorded, the reset the transmission memory today to try and satisfy my need to do something. I now waiting to hear back from the dealer on the next steps. I will also call GM again to give them this information. I am attaching picture that clearly show this problem. I also given the dealer the same pictures.

- Longmont, CO, USA

Parked and shut off, disconnected trailer. Truck rolled back while in park. I jumped out of way and tried to open door to stop. Door knocked me down and continued backwards dragging me. Final stop over edge of pond against tree stump. Had towed to dealer for inspection by Chevy engineer. 2 weeks no communication.

- Marshfield, MO, USA

Truck stationary. Started engine. Immediately message showed up on dashboard indicating steering assist low, drive carefully. No power steering. Traction control warning lit. Shifted into reverse; truck would not move as if in neutral. Truck move move forward in drive. Shut off engine and restarted twice. No change. Did not attempt to drive.

- East Alton, IL, USA