What was found
MASTER CAUTION ILLUMINATED DURING TAKEOFF FOR FUSELAGE DOOR. ABORTED TAKEOFF AT APPROXIMATELY 85 TO 100 KTS. MASTER WARNING INTERMITTENT WHILE TAXING BACK TO GATE. REMOVED FROM SERVICE. FLIGHT ATTENDANT REPORTED FINDING AFT PAX DOOR NOT FULLY LOCKED DURING TAXI IN. COMPLIED WITH OPERATIONAL TEST OF AFT PAX DOOR IAW AMM 52-12-00-710-802. OPS CHECKED GOOD. NO DEFECTS NOTED. NO PARTS REPLACED. AIRCRAFT RETURNED TO SERVICE.