What was found
APU DET INOPERABLE LIGHT ILLUMINATED AT CRUISE. GROUNDED-YES. REF B737-900 FIM 26-10 TASK 802, PERFORMED INITIAL EVALUATION, ENGINE/APU FIRE DETECTION CONTROL MODULE BITE PROCEDURE, FIM 26-10 TASK 801, NO FAULTS NOTED. REF B737-900 AMM TASK 26-15-01-210-801 C/W INSPECTION OF THE APU FIRE DETECTORS M1925, M1755 & M1756, FOUND POSSIBLE CORROSION ON TERMINAL STUD ON M1925 TAIL PIPE LOOP. CLEANED AND RESECURED TERMINAL. PERFORMED BITE CHECK OF ENG/APU CONTROL MODULE, NO DEFECTS NOTED. PERFORMED FIRE SYSTEM TEST, NO FAULTS ANNUNCIATED.