As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
NR 1 ENGINE FIRE LOOP TEST FAILED FOR LOOP A. FAULT LIGHT AND NR 1 ENGINE FIRE LIGHT WOULD NOT ILLUMINATE DURING TEST. ACFT GROUNDED. DURING TROUBLESHOOTING FOUND A BROKEN WIRE OFF TERMINAL LUG AT M1760. REPLACED THE TERMINAL LUG IAW SWPM. LEFT ENG FIRE DET SYS NOW OPS NORMAL. IAW AMM 26-11-00-410-801.