There are 3 owner-reported brakes complaints for the 2015 GMC Sierrain NHTSA's database. These are unverified consumer reports and may not reflect confirmed defects.
The contact owns a 2015 GMC Sierra 1500. The contact stated her husband was driving when the vehicle in front of them applied the brakes unexpectedly, the driver depressed the brake pedal but failed to stop the vehicle due to the brake pedal being resistant/ rigid causing the vehicle to rear-end the other vehicle. The contact stated no warning light was illuminated. The air bags did not deploy. The contact stated no one was injured nor sought medical attention. A police report was filed. The driver was able to continue driving to their destination. The contact took the vehicle to the local dealer, where it was diagnosed that the vacuum pump had to be replaced. The dealer replaced the vacuum pump back in October of 2022. The vehicle was repaired but the second vacuum pump was also defective and the dealer replaced it on-site for a third time. The vehicle was repaired. The manufacturer had not been informed of the failure. The failure mileage was approximately 85,500. The contact stated that the failure speed was no more than 70 mph.
I HAVE BEEN HAVING A PROBLEM WITH THE TRAILER BRAKE CONTROLLER ON MY K3500 TRUCK. RECENTLY THE MESSAGE "CHECK TRAILER WIRING" HAS BEEN COMING ON FREQUENTLY. AT THE SAME TIME, THE BRAKING CONTROLLER SHUTS OFF POWER TO THE TRAILER BRAKES. THIS HAS RESULTED IN A VERY UNSAFE CONDITION, ESPECIALLY WITH A TRAILER THAT WEIGHS OVER 14,000 POUNDS. THIS HAS BEEN GOING ON FOR 6 MONTHS NOW. REPEATED ATTEMPTS BY BOTH THE GMC DEALER AND THE TRAILER DEALER HAVE FAILED TO RESOLVE THE PROBLEM. I HAVE BEEN TOLD, BY THE DEALER, THAT THE PROBLEM STARTED APPROXIMATELY WITH THE 2014 MODELS. THE BRAKE CONTROLLER HAS BEEN UPGRADED, AND MADE MUCH MORE SENSITIVE TO SLIGHT DEVIATIONS IN THE TRAILER SYSTEM, CAUSING THE CONTROLLER TO "SHUT OFF" SO TO SPEAK. WHILE THIS WOULDN'T BE A BIG ISSUE NORMALLY, WHEN IT SHUTS OFF, YOU LOSE ALL BRAKING ABILITY TO THE TRAILER RESULTING IN AN UNSAFE CONDITION. THERE IS NO WAY TO OVERRIDE THIS AND ACTIVATE THE BRAKES. WHAT SEEMS TO BE HAPPENING IS A VERY SLIGHT DEVIATION IN THE RESISTANCE IN THE TRAILER BRAKE SYSTEM (BY 1 OHM OR LESS) AND THAT CAUSES THE "SHUTDOWN" IN THE CONTROLLER. TRAILER BRAKES WOULD WORK, IF THEY COULD GET POWER. BUT, THE CONTROLLER HAS SHUT DOWN, SO NO POWER. MYSELF (AND THE TRAILER SHOP) HAVE BEEN CHECKING THE INTERNET AND FINDING THAT THIS IS NOT AN ISOLATED INCIDENT. IT APPEARS TO BE HAPPENING WITH ALL THE BIG THREE MANUFACTURER TRUCKS, SINCE ABOUT 2014. PEOPLE HAVE BEEN COMING UP WITH SOME RATHER "CREATIVE" WAYS AROUND THIS, IN SOME CASES ELIMINATING THE ORIGINAL SYSTEM ENTIRELY. THIS IS JUST NOT ACCEPTABLE. AGAIN, THIS "NEW SYSTEM THE BIG THREE ARE PUTTING IN IS FAR WORSE THAT THE OLD, SIMPLY BECAUSE IT HAS NO ROOM FOR FORGIVENESS IN A TRAILER SYSTEM THAT MIGHT WORK OTHERWISE, BUT HAS A SLIGHT DEVIATION IN WHAT IS CONSIDERED "ACCEPTABLE" TO THE CONTROLLER. AT THE VERY LEAST, THERE SHOULD BE A FAIL SAFE METHOD.
TL*THE CONTACT OWNS A 2015 GMC SIERRA. THE CONTACT STATED THAT WHILE DESCENDING DOWN HILL AT NIGHT, THE LOW BEAM HEAD LIGHT PROVIDED POOR VISIBILITY. THE VEHICLE WAS NOT DIAGNOSED OR REPAIRED. THE MANUFACTURER WAS NOTIFIED OF THE FAILURE. THE FAILURE MILEAGE WAS 5. UPDATED 03/30/15*LJ UPDATED 06/23/2015*JS
Complaints are unverified consumer reports submitted to NHTSA. A high complaint count may reflect vehicle popularity, not defect severity. Data sourced from NHTSA public records.
Data synced from NHTSA on Apr 25, 2026