What was found
AT CRUISE ALTITUDE FL340 ENGINE FIRE / OVERHEAT DETECTOR LIGHT (FAULT) ILLUMINATED. SYSTEM TEST OF ENGINE FIRE / OVERHEAT NR 1 ENG AND APU NORMAL ENG NR 2 WILL ONLY TEST ON "B" LOOP. FAULT CODE 2614052. REPLACED ENG AND APU FIRE DET CONTROL MOD PER AMM 26 10 01. CTRL ENG NR 1 ENG NR 2 AND APU OPS TEST PASSED. TSR ISSUED. REPLACED FIRE DETECTORS AT LOWER FAN LEFT CORE UPPER FAN RIGHT CORE MW0326 HARNESS MW0315 HARNESS & MW0325 HARNESS. CHECKED MW0316 HARNESS FOR CONDITION NO DEFECTS NOTED. FOUND BROKEN WIRE ON RT CORE LOOP "A" FIRE DECTOR HARNESS P/N 325 027 506 0 REPLACED PER AMM 26 11 02 PB 401.