As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING PRE FLIGHT ENGINE FIRE TEST REVEALED FAULT LIGHT. GROUNDED-YES. CW B737-800 FIM 26-10 TASK 805 STEPS F(4)(D). MANIPULATED MW0325 HARNESS. RESISTANCE AT LT CORE LOOP (RIGHT SIDE OF ENGINE) RING TERMINAL ERRATIC WIRE EASILY BROKE OFF WHILE CHECKING. REMOVED AND REPLACED MW0325 CORE FIRE DETECTOR HARNESS, IAW B737-800 AMM 26-11-02/401. VERIFIED NR 1 ENGINE FIRE DETECTION SYS OPERATIONS TESTED NORMAL ON GROUND.