What was found
LOWER AFT BODY O/H LIGHT CAME ON DURING FLIGHT AT FL310. COMPLETED 'LWR AFT BODY O/H LIGHT ON' ABNORMAL/EMERG CKLIST. LIGHT REMAINED ON. DIVERTED TO FLL. ON LONG FINAL APPROACH W/ALL ENG AT IDLE FOR DESCENT, LIGHT WENT OUT. CKD KEEL BEAM LOOP M-367, AFT CARGO COMP LOOPS M-366, M-767 AND M323. NO LEAKS FOUND OR DISCREP IN LOOP/WIRING, CKD AFT AIRSTAIRS LOOP M-365 RT CKS GOOD. FOUND AIR LEAK NEAR LOOP M-322 LT AIRSTAIRS. TIGHTENED CLAMP ON AIR CLEANER OVERBOARD LINE. RAN ALL 3 ENG AT T/O PWR AND PART PWR FOR A FEW MINUTES. NO WARNING LIGHT CAME ON. OK FOR SVC.