What was found
ABORTED TAKEOFF AT 90 KNOTS WITH APU FIRE WARNING. APU WAS NOT RUNNING AT THE TIME. CREW PULLED FIRE HANDLE AND DISCHARGED APU FIRE BOTTLE. APU WAS NOT RUNNING. FOUND FIRE DETECTOR WIRING PIN CHAFFED AT THE FORWARD END BETWEEN FIRE SHROUD HALVES. NO DAMAGE TO THE APU OR COMPARTMENT OCCURRED. REPAIRED WIRES AND YELLOW SQUIB. RED SQUIB IN PLACE. TESTS NORMAL.