As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW PERFORMED AIR RETURN AFTER RESERVOIR LOW FUEL LIGHT ILLUMINATED ON ANNUNCIATOR PANEL WITH LH & RH WING LOW FUEL LIGHTS ILLUMINATED ON ANNUNCIATOR PANEL WHEN DAY-NIGHT SWITCH MOVED TO "DAY" MODE. FOUND MOISTURE ACCUMULATION UNDER FLOOR IN AREA OF FUEL RESERVOIR AND AREA IMMEDIATELY FORWARD OF THIS AREA WHERE CONNECTORS, WIRING AND EQUIPMENT ASSOCIATED WITH LOW FUEL WARNING SYSTEM.