What was found
FLT 0179 - ON TAKEOFF ROLL AT LAS EN ROUTE FOR MEX AFTER 80 KTS RECEIVED AUTO CALLOUT "RETARD THROTTLE" MESSAGE HEARD 3-TIMES, ABORTED TAKEOFF (2ND TIME), RETURNED TO GATE. MAINTENANCE REMOVED AND REPLACED BOTH NR 1 AND 2 FLT WARNING COMPUTERS IAW AWA, OPERATIONAL TEST WAS GOOD. VENDOR TEST OF FLT WARNING COMPUTER CONFIRMED FAILURE OF UNIT, UNIT FAILED DISCRETE INPUT TEST FOR INPUT CARDS NR 1 & 2, FAILURE WAS DUE TO A DEFECTIVE INPUT NR 2 BOARD. REPLACED DEFECTIVE INPUT NR 2 BOARD. ALSO CONFIRMED FAILURE OF FLT WARNING COMPUTER FOR UNIT FAILING OUTPUT TEST, FAILURE WAS DUE TO DEFECTIVE OUTPUT SRU, REPLACED OUTPUT SRU. PARTS REPAIRED IAW CMM.