The contact owns a 1991 N/A Ford F-150. The contact stated that after parking, turning the vehicle off, and exiting, the vehicle suddenly began to roll backwards. The contact was able to get back into the moving vehicle, press the brake pedal to stop the vehicle from moving. During the incident, the contact sustained a right shoulder injury that did not require medical treatment. The manufacturer and local dealer were not contacted. The VIN was not available. The failure mileage was 250.