As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CRUISE FLIGHT, CREW REPORTED A MAIN AND BACK UP PITCH TRIM MASTER WARNING MESSAGE WITH THE AUTO PILOT STILL CONNECTED AND AN AUTO TRIM CAUTION MESSAGE, AIRCRAFT WAS DIVERTED TO FSM. MAINTENANCE REMOVED AND REPLACED THE HORIZONTAL STABILIZER CONTROL UNIT AND C/W ETN. OPERATIONAL CHECK WAS GOOD AND AIRCRAFT WAS RETURNED TO SERVICE. (SW21200501218)