As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PHX-SFO - FLT 605 - AFTER TAKEOFF, THE TAKEOFF WARNING HORN WOULD NOT SHUT OFF. AIRCRAFT RETURNED TO GATE WITHOUT INCIDENT. MAINTENANCE PERFORMED TAKEOFF WARNING TEST PER AWA TASK CARD A1B31007, NO DEFECTS WERE NOTED. MAINTENANCE ALSO REPLACED ENGINE ACCESSORY UNIT AS A PRECAUTION. OPERATIONALLY TESTED ACCESSORY UNIT PER BMM 78-34-91, NO DEFECTS NOTED. AIRCRAFT RELEASED FOR SERVICE. (W)