What was found
ENGINE FIRE SWITCH DOES NOT ILLUMINATE, NR 2 ENGINE WITH OVERHEAT DETECTOR SWITCH IN NORMAL. ACFT GROUNDED. TROUBLESHOOTING FOUND THE NR 2 ENG TEST FAILS IN NORMAL AND B LOOP. A LOOP TEST NORMAL. OPERATED NR 2 ENGINE AND PERFORMED FIRE DETECTION MODULE BITE DIRECTLY AFTER RUN IAW AMM 71-00-00. FOUND THE NR 2 CORE B LOOP FAILED. PERFORMED FIM 26-10, TASK 805. REMOVED AND REPLACED THE CORE DETECTOR IAW AMM 26-11-01. OPERATED NR 2 ENGINE AND PERFORMED FIRE DETECTION MODULE BITE AFTER RUN. NO FAULTS. CHECKED GOOD.