What was found
AFTER BEING CLEARED FOR TAKEOFF BUT PRIOR TO SETTING TAKEOFF POWER THE MASTER WARNING FOR THE FUSELAGE DOORS ILLUMINATED THEN WENT OFF FOR THE FWD PAX AIRSTAIRS THIS HAPPENED 4 TIMES.THE DOOR APPEARED TO BE CLOSED AND SECURE. ABORTED TAKEOFF AND RETURNED TO THE GATE. REMOVED FROM SERVICE, CLEANED MCD SENSOR OFF DEBRIS ,TIGHTEN CAN PLUG ,A ND DO OPERATIONAL CHECK OF MCD.REF Q400 AMM TASK 52-11-00-710-802.DOOR MASTER CAUTION LIGHT ON PILOT SIDE WORKS ACCORDINGLY.NO FURTHER DEFECT AT THIS TIME.A/C IS GOOD FOR SERVICE.