As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PDX - PRIOR TO TAXI OUT, DID THE T/O WARN TEST TWICE AND GOT THE T/O HORN. THEN DID IT TWICE AND DID NOT GET THE HORN. THEN ON TAKEOFF APPLIED POWER AND GOT THE T/O HORN. SPEED WAS MORE THAN 60 KTS BUT LESS THAN 80 KTS. ABORTED TAKEOFF AND RETURNED TO THE GATE. FOUND PARK BRAKE SWITCH INTERMITTENT. REMOVED AND REPLACED PARK BRAKE CONTROL MODULE IAW Q400 AMM 32-44-21-000-801 AND 32-44-21-400-801. T/O WARNING OPS CHECKED GOOD. RETURNED TO SERVICE.