What was found
ENG 2 SYS B FIRE OVERHEAT HARD FAULT, SYS A OK. GROUNDED - YES. ENG #2 FIRE DETECTION OPERATIONAL TEST GOOD. CONTROL MODULE BIT SHOWS NO FAULTS. CONTROL MODULE REMOVED AND FIRE DETECTOR RANG OUT AT LOOPS B PINS 12 TO 2 AND 12 TO 10: BOTH WITHIN TOLERANCE (867 OHMS AND 1.8 OHMS). COMPARED TO LOOP A: SAME READINGS. ALL REF B737-900 FIM 26-10 TASK 805. MODULE RE-INSTALLED. OPERATIONAL TEST GOOD AND REPAIR CONFIRMATION GOOD REF FIM 26-10 TASK 805. GROUND VERIFICATION SUCCESSFUL. LOOP SWITCH IN FLIGHT DECK RETURNED TO NORMAL.