WHILE A NEW 2014 TRAVEL TRAILER WAS ATTACHED TO THE 2013 TOYOTA 4RUNNER THE WIRING DIRECTLY BEHIND THE 7PIN FEMALE RECEPTACLE CAUGHT ON FIRE. THE VEHICLE HAD BEEN RUNNING WITH THE TRAILER HOOKED UP FOR APPROXIMATELY 15-20MIN AFTER ALL LIGHTS WERE TESTED ON THE TRAILER.THE VEHICLE WAS TURNED OFF AND A FIRE EXTINGUISHER USED TO PUT OUT THE ELECTRICAL FIRE, AND THE BATTERY DISCONNECTED TO PREVENT ANY POWER. TOYOTA ROADSIDE SERVICE WAS CONTACTED AND LOCAL TOW COMPANY CAME AND PULLED THE FUSE FROM THE VEHICLE FOR THE TOWING. THE REST OF THE VEHICLE OPERATED AS NORMAL AND NO SIGNS OF ANY DAMAGE OR BLOWN FUSES. THE VEHICLE WAS THEN DRIVEN TO THE DEALER THE FOLLOWING DAY AS IT WAS DEEMED SAFE TO DRIVE DIRECTLY TO THE SHOP. TOYOTA DEALER WAS NOTIFIED AND STATED THAT THE TRAILER MOST LIKELY CAUSED THE ELECTRICAL SHORT AND STATED DOES NOT APPEAR TO BE WARRANTY WORK AS IT BACKFED INTO THE RECEPTACLE. I EXPLAINED THE SITUATION AND WAS INFORMED A TOYOTA FIELD REPRESENTATIVE AND SERVICEMANAGER WOULD CONTACT ME TO INSPECT THE TRAILER WIRING. I HAVE NOT BEEN CONTACTED SINCE. I HAD AN INDEPENDENT RV COMPANY TEST THE TRAILER ON 1/28/2014 AND CONFIRMED THE TRAILER ELECTRICAL SYSTEM AND 7PIN HARNESS ARE FULLY OPERATIONAL AND IN WORKING ORDER. THE TRAILER WAS PURCHASED NEW 1 WEEK AGO. THERE IS NO DAMAGE TO THE TRAILER OR ANY OF ITS ELECTRICAL COMPONENTS. THE TRAILER WAS HOOKED UP TO ANOTHER TRUCK AFTER THE INCIDENT AND TOWED WITH NO ISSUES. THERE IS A BRAKE CONTROLLER ATTACHED TO THE 4RUNNER WITH