As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
OUTBOUND CREW REPORTS A - LOOP FOR #2 ENGINE FIRE WARNING WILL NOT TEST. GROUNDED - YES. PERFORMED ENGINE FIRE DETECTORS INSPECTION CHECK PER B737-900 AMM 26-11-01/601. FOUND CORE FIRE DETECTION HARNESS, MW0325 TERMINAL LUG BROKEN. REPLACED CORE FIRE DETECTION HARNESS, MW0325 PER AMM 26-11-02/401. OPS CHECK NORMAL.