What was found
ON TAKEOFF ROLL AT APPROXIMATELY 20 KTS, THE FLIGHT CREW GOT A TAKEOFF WARNING HORN. THE CREW CHECKED FLAPS, TRIM AND SPEED BRAKE BUT TAKEOFF WARNING HORN REMAINED ON. THE CREW ABORTED TAKEOFF AND WENT TO A TAXIWAY WHERE THEY RAN UP THE ENGINES, BUT COULD NOT DUPLICATE THE CONDITION. MAINTENANCE ACCOMPLISHED TAKEOFF WARNING SYS CHECK IAW JOB CARD 03T10131001, NO DEFECTS WERE NOTED.