2018 GMC SIERRA 1500 Complaints

THE MIDDLE REAR SEATBELT FAILS TO LOCK WHEN RETRACTED, THEREFORE I CANNOT USE MY GRANDCHILD'S BOOSTER SEAT. THE DEALERSHIP HAS ORDERED A REPLACEMENT, BUT COST NEARLY $300. I BOUGHT THE VEHICLE NEW IN DECEMBER 2018, BUT HAVE NEVER HAD TO USE THE REAL SEATBELT UNTIL NOW. THEREFORE I DID NOT KNOW IT DID NOT WORK PROPERLY UNTIL NOW.

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

noticed ongoing vibration sounds like you are running over rumble lines on road.

Braking vehicle will cause brake pedal to vibrate and become soft while pressing it and requires more effort to stop vehicle. Service brake assist light laminates on info system. I know there is a recall for this currently but my vehicle is not listed for this all though i have the same issues. Recall is N202300860.

The main harness under the truck , front to back . There was a separation from the conduit, wires exposed and were arcing. Truck would not start . I have since had it fixed . I just feel truck is not that old , to soon for a problem like this . And it cost a lot of money.

Hit a small bump driving 55mph on highway and had sudden complete power steering loss and extremely hard to turn. Drove to a safe location and shut down truck for 1 hour. Upon restart power steering was operating normal. Proceeded back on the freeway and as soon as I hit a small bump with driver's side front tire the same thing happened again complete power steering loss. Drove to dealership and waiting for explanation. The truck is not safe due to inability to turn the wheel without power steering. For someone with less strength, this could be deadly on anything besides a straight road, needing to turn a corner, or to avoid a collision.

I purchased my 2018 GMC Sierra 1500 pickup truck new in 2018. To date it only has 28K miles on it. I have never used the trailer breaking system that it came equipped with. On 12/24/22 we were traveling to a family function for Christmas. The "service trailer break system" warning message came on and the chime chimed continuously until I got to my destination, about an hour away. This chime was very distracting and there was no way to turn it off. After arriving at my destination I turned the truck off hoping it was just a fluke. When I started the truck back up the "service trailer break system" warning light and chime continued. It continued for an hour on my way home. Again, this was very distracting and I was unable to focus 100% of my attention on the road and my driving. Thank fully I made it home okay. On 12/27/22 I took the truck to my mechanic to have him take a look. He said he has heard of this issue with these pickups. His diagnostic confirmed that the trailer breaking switch (on the dash) was functioning properly but said that the chassis control module was likely the culprit. He replaced the control module and it had to be programed by a factory technician. After this part was replaced the warning light or chime does not come on anymore. I have the defective part for inspection and the bill totaling $1191.86 for the repair upon request.

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.

I purchased this 2018 GMC pickup in May 2021. Starting in Nov 2022 I started getting a sporadic SERVICE TRAILER BRAKE SYSTEM warning light and chime. I have never towed a trailer using this trailer brake system on the vehicle, but the warnings come on sporadically. I have done some research and found this is not an isolated case as others have reported the same problem. Some owners have replaced the dashboard controller at their own expense, however this is now a well documented problem that goes beyond an isolated case. This is a defect of the trailer brake controller and should be recalled by GM at GM expense. It is a hazard to driving when the visual and audible chime come on sporadically. It's a distraction to safe driving and requires immediate intervention. I did advise my local dealer of the problem when the vehicle was serviced Dec 2022, however they did not have a technician available to work the problem. So I continue receiving the visual and audible warning every time I drive the vehicle. Please highlight this problem within your organization for a possible safety recall.

Gas leak. My 2018 gmc sierra 1500 has been giving me two codes for evap leak small and large and i notice a black spot on my drive way under the gas tank wich in fact was gas. I can see the gas tank is wet but it comes from the top part of the gas tank. I been looking for recalls on this but there isnt any for this specific year of GMC sierra 1500 slt.