The contact owns a 2021 Ford Bronco Sport. The contact stated that upon reversing the vehicle and depressing the brake pedal, there was an abnormal vibration sound coming from the brakes. There was no warning light illuminated. The vehicle was taken to a local dealer to be diagnosed, and the contact was informed that the rear brake parts were faulty and needed to be cleaned and replaced. The vehicle was not repaired. The manufacturer was notified of the failure. The approximate failure mileage was 46,000.