SERVICE BRAKES06/12/2026
The contact filed the complaint on behalf of the owner of a 2021 GMC Sierra 3500. The contact stated that while the vehicle owner was driving at an undisclosed speed, the driver noticed that the rear wheels were attempting to lockup. The contact stated that the failure was noticeable while driving forward and while reversing. No warning light illuminated. The vehicle was taken to the independent mechanic, where it was diagnosed with detached rear brake pads and detached rear emergency brake shoes. In addition, the rear brake caliber had seized. The vehicle owner was informed that the rear brake pads and the rear emergency brake shoes needed to be replaced, and the rear brake caliber needed to be repaired. The vehicle was repaired. The dealer was made aware of the failure. The contact was advised to contact the NHTSA Hotline to report the failure. The manufacturer was not made aware of the failure. The failure mileage was approximately 140,606.
POWER TRAIN11/24/2025
During takeoff the transmission acted as if it was in neutral while I was crossing traffic luckily, the semi truck that was coming towards me was able to stop. I had the vehicle towed to a shop. After the vehicle was towed to the shop the transmission acted normal when the mechanic searched the VIN number. There was a service bulletin issued by General Motors for this exact problem. Had the semi not been able to stop. It could’ve very well killed me or my children. I suppose if it would’ve killed someone, maybe general motors would finally do a recall for this very disappointed in general motors and the NHTSA, the fact that this is an ongoing problem and has not been fixed and as a customer, I was not even notified that this problem existed is very alarming.
ELECTRICAL SYSTEM,VISIBILITY09/08/2025
The contact owns a 2021 GMC Sierra 3500. The contact stated that while his wife had the vehicle idling with the rear defroster activated, shortly afterwards, she observed smoke coming from the plastic on the rear sliding window. After a visual inspection, the contact's wife observed that the plastic was melting, prompting her to deactivate the rear defroster. No warning lights were illuminated. The vehicle was taken to the dealer, who was unable to determine the cause of the failure. The vehicle was not repaired. The manufacturer was not notified of the failure. The failure mileage was 26,000.
BACK OVER PREVENTION08/14/2025
The contact owns a 2021 GMC Sierra 3500. The contact stated that while reversing, the back over prevention camera screen displayed an image of the ground. The contact stated that the image was approximately ten feet behind the vehicle. The vehicle was taken to the dealer; however, the failure was not duplicated. The dealer replaced the back over prevention camera system, however, the failure reoccurred. The contact stated that the original back over prevention camera was installed in another vehicle, and the back over prevention camera system worked as designed. The contact was informed that the back over prevention camera was not the cause of the failure. The manufacturer was made aware of the failure but provided no assistance. The failure mileage was approximately 70,000.
UNKNOWN OR OTHER05/12/2025
There is a known issue with these trucks with the infotainment screen blacking out, which renders the backup cameras inoperative. This is a huge safety risk and its astounding to me that this hasn't been recalled yet.
ELECTRICAL SYSTEM03/08/2025
When carrying the electronic key in my pocket the vehicle will lock/unlock presumably due to the remote contacting other items in the pocket. I have owned well over a dozen GM vehicles and never had this issue. I believe the remote design has the lock/unlock buttons too proud of the surrounding surface
UNKNOWN OR OTHER03/08/2025
Vehicle is put into park after driving. Shift to Park warning comes on while vehicle is in park. Vehicle will not shut off due to this warning and must be left running unoccupied.
POWER TRAIN01/27/2025
The contact's son owns a 2021 GMC Sierra 3500 Commercial Vehicle. The contact stated while her son was driving at an undisclosed speed uphill, the vehicle failed to shift to a gear higher than 5th gear. Additionally, the rear wheels locked up, causing the vehicle to come to a stop. The driver attempted to resume driving, but the vehicle failed to exceed 10 MPH. The contact was unsure whether a warning light had been illuminated. The vehicle was towed to the residence of the driver's girlfriend. The vehicle was then towed to the dealer, where it was diagnosed that the failure was related to NHTSA Campaign Number: 24V797000 (Power Train); however, the part to do the recall repair was not yet available. Additionally, the dealer informed the contact that the transmission needed to be replaced, but the part was not available. The vehicle was not repaired. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The manufacturer was made aware of the failure and a case was filed. The failure mileage was approximately 133,000. Parts distribution disconnect.
POWER TRAIN01/18/2025
Transmission had to be replaced from the dealership. Hard shifting dealership said truck was 23 days out of warranty. I couldn’t get into the dealership that truck was purchased from for 3 weeks. Had to go to the Jeff Gordon dealership, which is Chevrolet. And I had to replace the transmission.
ELECTRICAL SYSTEM,UNKNOWN OR OTHER,ENGINE11/01/2024
Multiple instances of diesel engine emissions system parts and software failure. While driving, towing or not, the DIC would randomly display a message that the DEF level is low and reduced speed will occur in x-amount of miles and that mileage would then begin a visible countdown on the DIC, sometimes much more quickly than the actual speed I was traveling. In other words, it might at first state 500 miles remaining, but then be counting down from 500 miles by one mile per second of time, or faster. Each instance, I would park and attempt to refill the DEF tank, only to discover that the tank is already full or near full. My truck’s DEF tank has now been replaced twice under warranty with the latest tank being installed at only 35,460 miles on the odometer. During the latest replacement, the technician also diagnosed and replaced the electrical wiring harness related to the DEF tank, stating that one of the connector pins was not reading the required voltage. There was also a faulty diesel particulate sensor that was replaced under warranty. This emissions system is problematic, and it is unsafe to due to the drive ability restrictions it imposes due to faulty software and equipment. I use my truck to tow, and it would make for a very unsafe condition to have my vehicle’s speed become limited as if the vehicle ran out of fuel. Mountain grades. Two-lane highways. Passing through bad neighborhoods. Driving in uninhabited areas, sometimes late at night. Family of 6 in the vehicle. Unacceptable. General Motors Corp. must create a permanent and fail-safe fix for this emissions system and implement the parts. The emissions system warranty should be extended from 80k miles to Lifetime to cover the vehicles affected.
POWER TRAIN10/01/2024
While driving 55mph on a 2 lane road, pulling a 5th wheel camper, the truck transmission downshifted by itself to a low gear. This caused a scary and immediate deceleration from 55 to 25mph. The trailer wanted to push into the oncoming lane the deceleration was so fast. The truck is at a dealership and they acknowledge the issue but not a fix other than putting back in the failed part. There was no warning and my readings say many others are having same issue. The small dealership we left the truck with (yemm Chevrolet in Galesburg Il) said they had 3 trucks with the same issue. The truck has been with the dealership for 7 weeks now.
SERVICE BRAKES04/19/2024
When starting the vehicle, I got a message to service the parking brake (this is the second time I’ve had this warning appear in the 21,000 miles I’ve owned it, first was approximately 5,000 miles ago). When this warning is active the parking brake does not engage, and can’t be used to stop the vehicle when the brakes fail as they did today. With 42,774 miles on the vehicle, and the onboard monitor for brake wear showing remaining brake life at 94% front and 96% rear, brake fluid reservoir between Max and Min the brake pedal went soft and the vehicle would not stop. I resorted to putting the vehicle in neutral and pumping the brakes until the pedal got hard. As soon as I let off the brake my vehicle began to roll backwards, stepped on the brake pedal again and the pedal again went to the floor without stopping or slowing the vehicle (pumping the brakes got it stopped again inches away from running into my house). The myGMC app notified me that I need to service the ABS system. I had the vehicle towed to the dealership for diagnostics and repair. Possibly related, this afternoon before the brakes stopped working I felt a mild vibration when traveling 20-35mph that resembled the vibration that occurs when a wheel bearing has begun to fail. Tow truck driver witnessed the vehicles inability to stop when putting it in neutral to load vehicle. It is unimaginable that a vehicle can be placed on the highway that has no backup system in the event of brake failure. Had a kid run out in front of me there would have been no way to avoid the accident (no other warnings appeared to indicate the vehicle was unsafe to drive. Brakes worked correctly and stopped appropriately until they didn’t).
Showing 12 of 20 complaints.