2025 GMC Sierra 3500

The electronic part of the truck gave a warning and shut off my trailer brake system while towing a 21K 5th wheel trailer (X2). The truck is available for inspection. Any part of the electronics package that has the ability to disable a trailer braking system while towing needs to be removed/disabled immediately. The truck has not been seen by a dealer yet. yes there was a warning I briefly saw both times, but I can't say what it said.

NHTSA ID

11732209

Incident

Apr 17, 2026

The contact owns a 2025 GMC Sierra 3500 used for hauling a 2026 Aluminum Trailer equipped with a DeeMaxx: DBI-7K-MAXX-SS-KIT brake kit. The contact stated that while driving at an undisclosed speed, the brake caliper bracket detached due to insufficient generic quality bolts included in the brake kit. The contact pulled over and had the trailer towed to an RV park. The vehicle was not diagnosed or repaired by an independent mechanic or dealer. The manufacturer was made aware of the failure but informed the contact that the failure was caused by improper installation. The failure mileage was unknown. The VIN was not available.

NHTSA ID

11731433

Incident

Apr 10, 2026

The contact owns a 2025 GMC Sierra 3500. The contact stated that the transmission was shifting hard and was jerking while shifting gear. Additionally, the vehicle failed to accelerate above 50 MPH. The messages “Reduced Acceleration” and “DEF Low” were displayed. While refueling the vehicle, the fuel gauge failed to correctly display the level of fuel inside the fuel tank until the vehicle had been driven for approximately 20 minutes. The vehicle was taken to the dealer to be diagnosed, and the contact was informed that the transmission needed to be updated. The system was recalibrated; however, the failure persisted. The vehicle was taken to another dealer, George Kell Motors (3808 Van Dyke Rd, Newport, AR 72112); and the system was recalibrated. However, the failures persisted. While driving approximately 60 MPH, the transmission was shifting hard, and the vehicle took over 2 hours to drive 19-miles. The engine temperature gauge fluctuated between 185 and 188 degrees. The vehicle was pulled over to the side of the road to cool down before continuing to drive, while not exceeding 40 MPH. The vehicle was taken to a third dealer, Fremont Chevrolet GMC Riverton (1401 N Federal Blvd, Riverton, WY 82501); who determined that the bell body needed to be replaced. The vehicle was scheduled to be repaired, but parts were on back order. The contact became aware that there was a recall related to failure; NHTSA Campaign Number: 26V129000 (Fuel System, Gasoline); however, the VIN was not included. The manufacturer was not made aware of the failure. The failure mileage was approximately 40,000.

NHTSA ID

11728507

Incident

Mar 1, 2025

Mileage

40,000 mi

I am reporting a potential safety defect involving Goodyear Wrangler TrailRunner AT tires size LT275/65R20. I purchased a new 2025 GMC Sierra 3500HD in August 2025. By the time the vehicle reached approximately 1,800 miles, noticeable sidewall bulges appeared on both rear tires. As a 36-year automotive professional, I recognized the serious safety risk posed by this condition and replaced all four tires at my own expense with a different brand. Since then, I have seen multiple reports of similar sidewall failures on brand-new trucks, which suggests this may be a systemic issue. Based on my experience and these reports, I believe this defect may be known to both Goodyear and GM but has not been adequately addressed. I urge the National Highway Traffic Safety Administration (NHTSA) to investigate this matter to determine whether these tires pose a significant safety risk to the public. Vehicle Information: Make & Model: 2025 GMC Sierra 3500HD Tire Model: Goodyear Wrangler TrailRunner AT tire size LT275/65R20. Mileage at Issue: ~1,800 miles Purchase Date: August 2025 Summary of Issue: Sidewall bulging on new tires, potential for blowout or loss of vehicle control.

NHTSA ID

11726517

Incident

Oct 15, 2025

Randomly when the truck is turned on, the turn signals will stop working, no noise, nothing. When this happens, the infotainment system also stops working. It is unsafe to be driving and not knowing if your signals are working or not. This has been happening since the truck was purchased from the dealer.

NHTSA ID

11722798

Incident

Mar 6, 2026

The truck automatically engages the parking brake ONLY when on an incline, never at any other time. I am so used to engaging the parking brake at all other times I also engage it when on an incline. The problem is the truck DISENGAGES the brake automatically after I've engaged it. This has happened multiple times when I've been towing a large boat on a launch ramp or towing my heavy 5th wheel. I can be fully exited from the truck and 10 ft away when it disengages and I watch it lurch forward. Simple answer would be for me to not engage the brake on an incline, but its a total habit all the time so I never remember to not engage it on an incline. This is a dangerous feature that needs to be removed ASAP. Thank you

NHTSA ID

11714433

Incident

Jan 30, 2026

Oil cooler for truck is defective and thus allowed all oil to be mixed with the coolant. GM is stating they will flush engine and replace with exact same part. Very common issue and sad to have a $100k truck and it is junk.

NHTSA ID

11706444

Incident

Dec 20, 2025

Picked up vehicle from Dealership new, with 12miles on the odometer. During the trip home (over 150+ miles each way) and at 54 miles a "Forward Collision System Unavailable" warning message appeared on the dash. Stopped for coffee and restarted the vehicle and the error cleared. It re-appeared at 235 miles, and again at 427 miles along with an OBD error P0700 @cycle#763, Occurrence Cycle #2608. Returned the Vehicle to the dealership service department for repairs. The vehicle was returned and we took the truck on our first trip to Yosemite and while driving it the cruise control released the throttle times driving on a 4 lane Hwy 152. Then on the backside of Pancho Pass we entered the town of Los Banos. While driving in a 45 MPH section of Hwy 152, with no other cars in front or behind us, the truck performed an emergency stop. It applied the brakes at maximum force causing the front to dive hard and the rear tires to lose traction with the antilock cycling the brakes on and off, causing them to slip bringing the truck to a stop. At no time did the dash or the HUD display flash the collision warning or any error messages, I applied throttle and moved the Truck off the Hwy to the side of the road. Checked all pages on the dash for any indication of problems, and we drove to a parking lot inspecting the truck top to bottom to see if there were any obstructions, damage to the bumper sensors, or windshield. Returned the Truck to the dealership a second time for repairs. Received the vehicle back and during the drive home we Stopped for Dinner in San Jose and the "Forward Collision System Unavailable" returned again. Returned the vehicle for service a third time and notified Manufacture of the issues.This is a Major safety defect that GM cannot seem to repair. Current mileage of vehicle 3098.

NHTSA ID

11705815

Incident

Aug 16, 2025

This Preliminary information communicates an issue with the SES MIL and DTC P062B and engineering is currently investigating.

This PI communicates diagnostic information to assist Technicians with a possible transmission shudder

This PI Communicates information to ensure Memory Recall is enabled to ensure memory mirrors return to set position after curbview assist is used.

This PI provides information to repair the door water deflector which is not sealed properly allows water into the door jam/sill area.

This PI provides diagnostic tips for diagnosing electric trailer brakes issues.

PI to help diagnose A/C concern