As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
BIL-ON FLIGHT NUMBER 2483-SUPP, DURING TAXI OUT, SMOKE AFT LAV WARNING LIGHT CAME ON. SMOKE COULD BE SEEN AND SMELLED IN CABIN. PERFORMED GROUND RUN, NO ODOR NOTED. LAVATORY DETECTOR DID NOT GO OFF. OPERATED RT PACK, NO CAUTION MESSAGE NOTED. COMPLIED WITH OPERATIONAL CHECK OF AIR CONDITION SYSTEM, OPERATIONAL CHECK GOOD. NO PARTS REPLACED. AIRCRAFT RETURNED TO SERVICE.