What was found
ON FO PREFLIGHT - ENG OVERHEAT + FIRE DET LOOP B FAILED TEST. GROUNDED - YES. REPOSITION ENG #1 & ENG #2 OVHT DET SWITCH TO NORMAL, PERFORMED ENG FIRE DETECTION OPS NORMAL B737-800 AMM 26-11-00-710-801 & PERFORMED ENGINE / APU FIRE DETECTION CONTROL MODULE BITE PROCEDURE NORMAL NO FAULTS NOTED B737-800 FIM 26-10 TASK 801, PER ASA TECH SERVICES REPLACED NEW ENGINE/APU FIRE DETECTION CONTROL MODULE (M279), PERFORMED INSTALLATION TEST NORMAL & BITE TEST NORMAL SAME ABOVE FIM & AMM.