As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
TAKEOFF WARNING HORN SOUNDED AS POWER WAS ADVANCED FOR TAKEOFF. TEST WAS SUCESSFUL AND ALL PARAMETERS WERE SET NORMAL. REPLACED THE NR 2 INPUT-OUTPUT PROCESSOR IAW MAINTENANCE 6314101. OPS CHECKS GOOD IAW AMM 31-41-00-710-802. RETURNED TO SERVICE.