What was found
(CAN) CREW HAD A FIRE WARNING LIGHT COME ON IN FLIGHT, CREW FOLLOWED PROCEDURES AND TURNED THE AIRCRAFT 90 DEGREES TO RULE OUT LIGHT POSSIBLY TRIPPING DETECTORS AND LIGHT REMAINED ON. NO SIGN OF FIRE WAS NOTED VISUALLY ON WING NOR ON THE GLANCE OF INSTRUMENTATION. CREW THEN CARRIED ON AND THE LIGHT WHEN OFF PRIOR TO APPROACH. MAINTENANCE NOTIFIED AND INSPECTED, FUNCTION CHECKED SYSTEM. SYSTEM FUNCTIONED NORMALLY. WIRING IN NACELLE FOUND WET DUE TO THE WEATHER CONDITION ENROUTE WHICH WE HAVE DETERMINED A CAUSE FOR AN INTERMITTENT WARNING IN THE PAST. MAINTENANCE SEALED WIRING AS REQUIRED TO REDUCE THE CHANCE OF THIS HAPPENING WHILE FLYING IN PRECIP. (TC NR 20060921005)