What was found
DURING CRUISE FLIGHT AT FL 330 MACH .82, THE LOWER AFT BODY OVERHEAT LIGHT STARTED TO LIGHTLY FLICKER INTERMITTENTLY. LIGHT RARELY FLICKERED ON AND WAS MOSTLY COMPLETLEY OUT. SUSPECTED A SHORT IN THE IND SYSTEM. FURTHER DOWN LINE THE WARNING LIGHT FLICKERED MORE OFTEN AND WAS CLOSE TO FULL BRIGHTNESS. FOLLOWED RED TAB PROCEDURES WITH ALL THREE THROTTLES AT IDLE AND ALL BLEEDS OFF. LIGHT WOULD NOT EXTINGUISH. ENGINE OR WING ANTI-ICE NEVER USED. STRUT AND AFT BODY OVERHEAT TESTS NORMAL. VISUALLY INSPECTED VENTRAL STAIR AREA FOR DUCT LEAKS, NONE NOTED. FOUND DETECTION LOOP CHAFING ALONG ROUTING BETWEEN FRAME STA'S 1240 TO 1303 LEFT HAND SIDE, MOVED ELEMENT AWAY FROM STRUCTURE.