As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFT CARGO FIRE DETECTION WILL NOT TEST "DETECTOR FAULT" LIGHT ILLUMINATES. FOUND SMOKE DETECTOR POSITION B2 AT AFT CARGO PIT FAULTY. REMOVED AND REPLACED DETECTOR B2 REF MM 26 16 01 000 801. PERFORMED OPS TEST REF MM 26 16 00 710 801. SYS CHECKS NORMAL. OPERATIONAL PROCEDURE RESET. PLACED SWITCH AT NORMAL POSITION ON CARGO FIRE TEST PNL. OPS NORMAL.