TL* THE CONTACT OWNS A 2010 FORD F-150. THE CONTACT STATED THAT WHILE DRIVING APPROXIMATELY 40 MPH, THE REAR WINDOW DEFROSTER WAS ACTIVATED WHEN A SMALL SPARK IGNITED FROM THE REAR PASSENGER'S SIDE DEFROSTER. A POPPING AND CRACKLING NOISE WAS ALSO HEARD AT THE TIME OF FAILURE. THE VEHICLE WAS MANEUVERED TO THE SHOULDER AND THE FLAME WAS NO LONGER VISIBLE. IN ADDITION, SMOKE EMITTED INSIDE OF THE VEHICLE. THE CONTACT DETACHED THE DEFECTIVE FUSE FOR THE DEFROSTER. THE VEHICLE WAS NOT DIAGNOSED OR REPAIRED. THE MANUFACTURER WAS NOTIFIED OF THE PROBLEM. THE APPROXIMATE FAILURE MILEAGE WAS 75,000.