2025 GMC Sierra 3500 Problems

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.

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.

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.

weekly you will start the truck and have no audio of any kind. No blinker noises no collision warning noises, no radio, no on star noise. No sound at all and sound will never come back on until you turn truck off and wait 20 mins. GMC says it's a known software issue, but this has been going on since I bought the truck brand new back is April of 2025. I live in a hands free while driving state when it's come to cell phone use and can't even take a call with no audio of any kind. I don't see how GMC can say this isn't a safety issue.

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.

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.

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.

weekly you will start the truck and have no audio of any kind. No blinker noises no collision warning noises, no radio, no on star noise. No sound at all and sound will never come back on until you turn truck off and wait 20 mins. GMC says it's a known software issue, but this has been going on since I bought the truck brand new back is April of 2025. I live in a hands free while driving state when it's come to cell phone use and can't even take a call with no audio of any kind. I don't see how GMC can say this isn't a safety issue.

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.

I am reporting a potentially serious and widespread safety defect involving Goodyear Wrangler TrailRunner AT tires installed as factory equipment on General Motors trucks. My 2025 GMC Sierra 3500HD Denali has just 5,800 miles. Both rear tires, with DOT code 2724, have developed identical sidewall bulges behind the “NER” in the “TrailRunner” stamp. These bulges are consistent with internal structural failure, not road hazard damage. The truck has never struck a pothole or curb, and there is no evidence of impact or external damage. I have personally inspected several brand-new GM trucks on dealer lots, equipped with the same Goodyear tires, showing the exact same sidewall bulge in the same location. These trucks also have newer DOT Manufacture date stamps. Most importantly, these vehicles have never been driven, which strongly suggests a tire manufacturing defect, not a driver-related issue. At my first scheduled service, the dealer’s service department refused to rotate the tires, citing the bulges as a safety risk. I filed a formal complaint with GM and requested that they involve Goodyear. GM denied the request, claimed the damage was from road impact (without evidence), and stated that the decision was final and not disputable. They refused to conduct any further investigation or escalate the claim. I believe GM’s refusal to act on a potential structural defect, especially one seen across multiple new vehicles, demonstrates a failure to exercise due diligence and exposes the public to unnecessary danger. A blowout from these bulges could lead to serious injury or fatal crashes. I am urging NHTSA to open a defect investigation into Goodyear Wrangler TrailRunner AT tires, particularly those with DOT code 2724 and newer, as installed on GM trucks. I am prepared to submit photographs and dealership documentation as necessary.

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.

Tail gate has opened twice while driving down the road.

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.

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.

Hose from power steering pump came off causing truck to loose power steering and brakes. Fortunately we had just exited the interstate and were in a parking lot when this occurred. Truck was towed 90 miles to dealer who confirmed that hose was incorrectly installed by factory