What was found
KMIA - FLT 68166 - AT 30,000 FEET, FIRE WARNING ON NR 4 ENGINE, WITH LIGHT IN HANDLE AND BELL, AFTER PULLING NR 4 POWER LEVER TO IDLE. FIRE WARNING WENT OUT. FOUND FIRE WARNING DETECTOR LOOP GROUNDED TO AFT INBOARD COWL. REPAIRED AS NECESSARY. OPS CHECK NORMAL ON RUN-UP IAW MM 26-2-3. (X)