As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PDX - TAKEOFF WARNING HORN ACTIVATED ON TAKEOFF. ABORTED TAKEOFF, RAN CHECKLIST, TALKED TO MAINTENANCE CONTROL AND RAN TORQUE UP. DID NOT GET THE TAKEOFF WARNING HORN DURING CONFIGURATION CHECK. ATTEMPTED SECOND TAKEOFF AND RECEIVED TAKEOFF WARNING HORN. CLEANED AND LUBED SWITCHES UNDER PEDESTAL. GROUND RAN AIRCRAFT. OPERATIONAL CHECK GOOD. NO PARTS REPLACED. AIRCRAFT RETURNED TO SERVICE.