As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMBOUT, THE FLIGHT CREW RECEIVED AN AURAL "TRIM" WARNING MESSAGE AND FOUND THE MAIN AND BACK-UP PITCH TRIM TO BE INOPERATIVE. THE CREW DECLARED AN EMERGENCY, RETURNED TO THE FIELD, AND MADE AN UNEVENTFUL LANDING. MX CLEANED THE BACK UP TRIM SWITCH AND RESET THE SYSTEM IAW THE FAULT ISOLATION MANUAL AFTER WHICH ALL OPS CHECKS WERE SUCCESSFULLY COMPLETED.