Mileage when the problem started
Owner reports
Selected complaints filed with NHTSA by 2018 GMC Sierra 1500 owners, lightly cleaned up (personal details are redacted by NHTSA).
The contact owns a 2018 GMC Sierra 1500. The contact stated that the vehicle failed to shift into gear as needed. The vehicle was taken to the dealer, where the contact was informed that an unknown part was loose. The vehicle was repaired. Additionally, the contact stated that while driving at various speeds, there was an abnormally loud sound coming from underneath the vehicle near the transmission. The vehicle was taken to the dealer, where the contact was informed that no failure was found. The contact stated that while driving 55 MPH, the vehicle started to decelerate unintentionally. The contact stated that there was smoke coming from the brake pedal. The contact pulled over to the side of the road and allowed the vehicle to cool down however, the brakes locked up unexpectedly. The vehicle was driven to the dealer to be diagnosed. …
The contact owns a 2018 GMC Sierra 1500. The contact stated that while depressing the brake pedal, the brake pedal displayed more resistance than expected, causing the contact to have to apply more pressure while depressing the brake pedal. The contact stated that the braking distance was extended due to the failure. The vehicle was taken to the dealer who diagnosed that the brake vacuum pump had failed and needed to be replaced. The vehicle was not repaired. The contact became aware of NHTSA Campaign Number: 19V645000 (Service Brakes, Hydraulic); however, the VIN was not included. The manufacturer was informed of the failure and confirmed that the VIN was not included in the recall. The manufacturer referred the contact to the NHTSA Hotline to report the failure. The failure mileage was approximately 75,000.
The contact owns a 2018 GMC Sierra 1500. The contact stated that while driving at various speeds, while depressing the brake pedal to slow down, the brake pedal lost pressure, and the vehicle experienced a reduction in braking power. The contact had to depress the brake pedal with additional force to properly slow the vehicle. There was no warning light illuminated; however, the message "Brake Assist" was displayed on the instrument panel. The local dealer was not contacted, and the vehicle was not diagnosed or repaired. The manufacturer was not notified of the failure. The approximate failure mileage was 135,000.
The contact owns a 2018 GMC Sierra 1500. The contact stated while driving approximately 35 MPH, the assist brake warning light was illuminated and the contact had to depress the brake pedal to the floor to stop the vehicle. The contact took the vehicle to the local dealer, where it was diagnosed with needing the vacuum pump to be replaced. The vehicle was not repaired but was pending repairs. Upon investigation, the contact associated the failure with NHTSA Campaign Number: 20V603000 (Service Brakes, Hydraulic). The manufacturer had not been informed of the failure. The failure mileage was approximately 37,000.
The contact owns a 2018 GMC Sierra 1500. The contact stated that while her husband was inside the parked vehicle, the ABS warning light illuminated. The contact researched the failure and was made aware of NHTSA Campaign Number: 00V055000 (Service Brakes, Hydraulic); however, the VIN was not included. The vehicle was taken to a dealer where it was diagnosed that the ABS control module had experienced a failure; and the ABS control module needed to be replaced. The vehicle was not repaired. The manufacturer was notified of the failure. The failure mileage was approximately 112,000.
Trailer brake modulator on 2018 GMC Sierra does not consistently signal trail brakes to work when needed on our 7,500 pound RV trailer. GMC dealer eventually found that the battery cables were undersized as installed with the factory towing package on the 2018 GMC Sierra. The undersized battery cables do not consistently deliver adequate voltage to the trailer brake modulator on the GMC Sierra, so inconsistent electric brake function for our 7,500 pound RV trailer. Dealer had difficulty diagnosing the problem as being the wrong factory-installed battery cables to go with the factory-installed trailer towing package. So it cost us $1,600 to have the GMC dealer correct a problem caused by the GMC factory installing undersized battery cables. Fortunately, this did not result in a collision for us, but it might for someone else. …
I purchased my 2018 GMC Sierra 1500 pickup truck new in 2018. To date it only has 28K miles on it. I have never used the trailer breaking system that it came equipped with. On 12/24/22 we were traveling to a family function for Christmas. The "service trailer break system" warning message came on and the chime chimed continuously until I got to my destination, about an hour away. This chime was very distracting and there was no way to turn it off. After arriving at my destination I turned the truck off hoping it was just a fluke. When I started the truck back up the "service trailer break system" warning light and chime continued. It continued for an hour on my way home. Again, this was very distracting and I was unable to focus 100% of my attention on the road and my driving. Thank fully I made it home okay. On 12/27/22 I took the truck to my mechanic to have him take a look. …
I purchased this 2018 GMC pickup in May 2021. Starting in Nov 2022 I started getting a sporadic SERVICE TRAILER BRAKE SYSTEM warning light and chime. I have never towed a trailer using this trailer brake system on the vehicle, but the warnings come on sporadically. I have done some research and found this is not an isolated case as others have reported the same problem. Some owners have replaced the dashboard controller at their own expense, however this is now a well documented problem that goes beyond an isolated case. This is a defect of the trailer brake controller and should be recalled by GM at GM expense. It is a hazard to driving when the visual and audible chime come on sporadically. It's a distraction to safe driving and requires immediate intervention. …
I kept getting a constant alert on my vehicle dash board that said "service trailer brake system" the beeping alert was quite literally constant and it covered up the digital speed odometer, every time I tried to acknowledge the alert it would just pop up and start beeping again. I searched online and quickly realized that this problem with the brake system has plagued GM vehicles for several years and I attempted to fix the issue myself by buying factory parts that other GM owners stated was the issue but it did not correct the issue. I ended up needing to take it to a GM service center and my vehicle was there for 2 business days and it ran me several hundred dollars to have GM fix the issue in the electrical brake system. …
While driving 35 miles per hour in the early morning hours I came to a 4-way intersection and applied the brakes slowly. Suddenly, I lost all power in the brakes and the steering wheel locked up. The lights, and stereo remained on, and my dash board display immediately showed a red check engine light. I immediately turn on my hazard lights, turned the ignition key off and tried to restart the truck. There was no clicking sounds. The truck would not start but the lights dimmed and the dash display now showed an intermittent yellow, flickering check engine light. After roughly 30 minutes while waiting for AAA to arrive I tried the ignition key and the truck started up with a red check engine light. Rather than attempting to drive I had AAA tow my vehicle to the Chevrolet dealership where I purchased the truck.
Related recalls
Service brakes, hydraulic › Power assist › Vacuum
General Motors LLC (GM) is recalling certain 2018 Cadillac Escalade, Chevrolet Silverado 1500 and Tahoe, GMC Sierra 1500 and Yukon vehicles equipped with either a 5.3L or 6.2L V8 engine. The output of the mechanical vacuum pump can decrease over time, decreasing the amount of vacuum/power brake assist.
Remedy: GM will notify owners, and dealers will reprogram the Electronic Brake Control Module, free of charge. The recall began November 11, 2020.
Service brakes
General Motors LLC (GM) is recalling certain 2015-2020 Chevrolet Suburban, Tahoe, and GMC Yukon, and 2014-2018 Chevrolet Silverado 1500 and GMC Sierra 1500 vehicles equipped with a 5.3-liter engine, a 3.08-ratio rear axle and four-wheel drive.
Remedy: GM will notify owners, and dealers will reprogram the EBCM, free of charge. The recall began December 11, 2019. Owners may contact Chevrolet customer service at 1-800-630-2438 or GMC customer service at 1-800-462-8782.
Service brakes, hydraulic › Power assist › Vacuum
General Motors LLC (GM) is recalling certain 2015-2017 Cadillac Escalade, 2014-2018 Chevrolet Silverado, GMC Sierra, 2015-2018 Chevrolet Suburban, Tahoe, GMC Yukon vehicles. The amount of vacuum created by the vacuum pump may decrease over time.
Remedy: GM will notify owners, and dealers will reprogram the Electronic Brake Control Module, free of charge. The recall began October 8, 2019.
Brake complaints in other Sierra 1500 years
Frequently asked questions
How common are brake problems on the 2018 GMC Sierra 1500?
NHTSA has 44 complaints about the brakes of the 2018 GMC Sierra 1500, 14% of the model year's 305 complaints.
Is there a recall for 2018 GMC Sierra 1500 brake problems?
Yes — NHTSA recall 20V-603 (vacuum, Oct 1, 2020); NHTSA recall 19V-761 (service brakes, Oct 24, 2019); NHTSA recall 19V-645 (vacuum, Sep 6, 2019). Recall repairs are free at authorized dealers.
At what mileage do 2018 GMC Sierra 1500 brake problems start?
Half of the complaints with a recorded mileage happened before about 23,000 miles, and 57% before 25,000 miles.
Is it dangerous?
Owners linked 2 crashes, 0 fires and 0 injuries to brakes problems on this model year. If you notice symptoms, have the car checked before driving further.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) — owner complaints through October 20, 2026, recalls and defect investigations; fuel economy from the EPA. Complaints are unverified reports and are not proof of a defect. How we rate model years.