This data is from the NHTSA — the US gov't agency tasked with vehicle safety. Complaints are spread across multiple & redundant categories, & are not organized by problem.
So how do you find out what problems are occurring? For this NHTSA complaint data, the only way is to read through the comments below. Any duplicates or errors? It's not us.
GMC has a problem with the electronic brake controller on their 2024 Sierra 2500HD and 3500Hd trucks. All trailers are required to have trailer brakes. In addition the trailer must be equipped with an auxillary battery to activate the emergency breakaway brakes. If the voltage on this battery is higher than the towing vehicle battery, the vehicle controller can display a trailer wiring fault display. When this happens there are no brakes on the trailer. This fault happens intermittantly and can last between 10 seconds to 30 seconds. We constantly have this problem with our vehicle. On two occasions we were in an emergency situation towing a12,500 lb load and had no brakes. This is A SEVERE SAFETY CONCERN. The GMC dealer stated that the problem is because our trailer uses a regular car battery to work the hydraulics and the brakes. They stated that the controller pings the trailer to see is anything is connected and that the car battery can interfear with this signal. When this signal does not return the controller senses that no trailer is connected and disables the trailer brakes. The trailer that we have is new and it is wired according to industry standards. Thre are thousands of trailers on the road that have this configuratiion. We have inspected the trailer and cannot find wiring problems. We have towed the same tyrailer with two different trucks and do not have this problem. A quick search on the internet will reveal that many other people are experiencing the same problem.
Upon starting our 2024 GMC Sierra 2500HD after towing a camping trailer for approximately 200 miles, the following error notifications would cycle every 20 seconds to 5 minutes: "Check Trailer Wiring" "Service Trailer Brake System" The trailer brake would become disabled after these errors, and sometimes would connect with a "trailer brake connected" message, only to repeat every 20 seconds to a few minutes later. During the 60 minutes in which I drove to an RV dealership to have the problem looked at, on multiple occasions, I had no trailer brakes when braking, or had no trailer brakes until the trailer brakes suddenly connected at below the speed of 35 - 25 MPH. GM has acknowledged document ID: 6420021 and bulletin #23-NA-149 that this could happen when pulling a trailer with a battery, generator, or solar charger that has a higher state of charge than the vehicle battery. This is an extremely unsafe condition that could easily cause a rear-end accident or a jackknife condition of the vehicle/trailer combination. GM has known about this issue since at least June of 2023, and as of September, they have an updated trailer brake controller that is supposed to correct this issue. There should be an immediate recall of the vehicles involved to have the trailer brake module replaced with the updated part.
- Oviedo, FL, USA
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- Pasco, WA, USA