As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER DEPARTURE, THE CREW WAS WAS ALERTED TO AN ANNUNCIATOR INDICATING THAT THE PRIMARY PITCH TRIM HAD FAILED. ELECTED TO RETURN TO DEPARTURE. TROUBLESHOT AND DETERMINED THAT THE PRIMARY PITCH TRIM ACTUATOR CONTROL BOX HAD FAILED. THE CONTROL BOX WAS REPLACED, AND FUNCTIONAL CHECKS WERE SATISFACTORY.