As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ENGINE # 1 FIRE DETECTOR LOOP A TESTS BAD. GROUNDED - YES. STILL SHOWS LOOP A LH CORE DETECTOR ON BITE. RESISTANCE CK AT LEFT CORE WITHIN LIMITS. CONTINUITY SHOWS OPEN FROM LH CORE TO DP1501. REPLACED MW0325 CORE HARNESS REF B737-900 AMM 26-11-02 & B737-900 WDM 26-11-11. GROUND VERIFICATION TEST PASS.