What was found
SHORTLY FOLLOWING ENGINE START, NR 4 ENG SHORT CIRCUIT FIRE CAUTION LIGHT BEGAN FLASHING. LOOP-A TESTED OK SWITCHED TO B-LOOP MEL 26-2-3 CONTROL 15484. DEFERRED NR 4 ENGINE A-LOOP IAW MEL 26-2-3 DMI 15484 PLACARD INSTALLED. SHORTLY FOLLOWING ENGINE START NR 4 ENG SHORT CIRCUIT FIRE CAUTION LIGHT BEGAN FLASHING (LOOP-A), TESTED OK SWITCHED TO LOOP-B. INSPECTED NR 4 ENG LOOP-A GROMMETS & CONNECTIONS. R & R NR 4 POWER CONTROL UNIT, NO HELP. DMI 15484 REMAINS OPEN FOR FURTHER TROUBLESHOOTING. REPLACED ORIGINAL CONTROL UNIT IAW 26-10-00. DMI 15484, NR 4 ENGINE SHORT CIRCUIT LIGHT BEGAN FLASHING, LOOP-A. R & R A-LOOP CONNECTOR P17051 IAW MM. OPS CHECKED OK. NO DEFECTS NOTED. THIS CLEARS DMI 15484.