What was found
NR 1 ENGINE A LOOP OF FIRE DETECTION SYSTEM INOP. GROUNDED - YES. ENGINE/APU FIRE BITE SHOWS WIRING OPEN OR DETECTORS FAULT. FAULT LIGHT ILLUMINATED WHEN SWITCHED TO A LOOP. AFTER OPENING INBOARD TR FAULT LIGHT EXTINGUISHED. DISCONNECTED ALL A LOOP DETECTORS, GVI ON ALL CONNECTION, NO DEFECTS NOTED. RESISTANCE CHECKED ON ALL DETECTORS - WITHIN LIMITS, NO FLUCTUATION DURING TAPPING. SECURED ALL WIRE HARNESS FOR DETECTORS. DURING CONTINUITY CHECKS FOR CORE LOOPS, OPEN LINE WAS OBSERVED WHEN FLEXING MW0325. REMOVED & REPLACED MW0325 ENGINE CORE FIRE HARNESS, REF FIM 26-10 TASK 08 & WDM 26-11-11, ENGINE FIRE TEST NORMAL.