The contact owns a 2015 GMC Sierra 1500. The contact stated while driving at an undisclosed speed, the brake pedal was depressed; however, the vehicle failed to stop as intended. The vehicle was taken to the dealer; however, the vehicle was not diagnosed. The vehicle was not repaired. The contact stated that the failure became a persistent failure. The manufacturer was made aware of the failure. The contact referenced an unknown recall repair as a possible cause of the failure; however, the VIN was not included. The failure mileage was unknown.