As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
#A FIRE LOOP SHOWS FAULT UPON TESTING, #1 FIRE SWITCH DOES NOT ILLUMINATE ON TEST ALSO, OPS NORMAL IN B LOOP. GROUNDED - YES. REMOVED AND REPLACED ENG #1 MW0315 HARNESS REF B737-900 AMM 26-11-02-400-801, OPS NML REF AMM 26-11-00-710-801. MOVED SWITCH TO NORMAL.