What was found
DURING T/O ROLL, RT ABOUT 80 KTS, WE HEARD A BEEP, FOLLOWED BY THE T/O WARNING HORN A FEW SECONDS LATER. ABORTED THE T/O AROUND 90 KTS USING REVERSE POWER AND MODERATE BRAKING. THE T/O WARNING TEST WAS NORMAL DURING TAXI OUT AND AFTER RUNNING THE E & A CHECKLIST. THE ACFT CONFIGURATION WAS CORRECT AND THERE WERE NO OTHER ASSOCIATED CAUTIONS OR WARNINGS. OP'S CHECK OF TAKEOFF WARNING SYSTEM, R & R OF CONDITION QUADRANT, R & R NR 1 IOP. OP'S TEST GOOD. R & R NR 1 IOP, PERFORMED LLM RTS TEST IAW MAINTENANCE 6314101. RETURNED TO SERVICE.