The contact owns a 2015 GMC Yukon. The contact stated while driving 5 MPH, the brake pedal was depressed, but the vehicle failed to stop as intended. The brake warning light was illuminated. The contact stated that the brake pedal was depressed to the floorboard. The vehicle was slowly driven to the dealer; however, no cause for the failure was found. The vehicle was not repaired. The contact stated that the failure persisted. The contact associated the failure with NHTSA Campaign Number: 19V645000 (SERVICE BRAKES, HYDRAULIC). The manufacturer was not made aware of the failure. The failure mileage was approximately 90,000.