NHTSA Complaint #11668227 — 2025 GMC SIERRA 3500

While towing my fifth wheel trailer, the truck intermittently disconnects the trailer brakes while in motion. This results in a sudden loss of roughly 75% of my braking capability, creating an extremely dangerous situation. I have a professional driving background, which has helped me avoid an accident so far, but this issue could easily result in a collision, especially under emergency braking or downhill conditions Service Attempt: On June 17, 2025, I brought the vehicle to Madras Chevrolet in Oregon. The dealership acknowledged the issue but stated the truck is “within GM parameters,” so no repairs were made. They claimed the problem might be with the trailer, but I’ve confirmed the trailer works properly with other tow vehicles. This appears to be a systemic electrical or control issue with the truck. Safety Concern: No vehicle should be allowed to disable trailer brakes while moving. This is a clear design or control system fault. I am concerned that other GMC or GM truck owners may be at similar risk and urge the NHTSA to investigate this problem before it results in serious injury or death. PS. On social media most owners say this is happening to them