As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SHIP 3809 DOOR 1L ENTRY LIGHT CONTINUALLY FLASHES ON & OFF (STROBING) AT GATE WITH APU AND EXT PWR. CLICKING SOUNDS CONTINUOUSLY HEARD BEHIND CB PANEL BEHIND F/O SEAT. CORRECTIVE ACTION: RE-SEATED RELAY FOR DOOR 1L ENTRY LIGHT. NOW CKS OK. (6526604).