What was found
PILOT STATED BOTH CAS MESSAGES POSTED. TURNED OFF AUTOPILOT AND STAB TRIM CHANNELS 1 AND 1 WERE OFF LINE AND WOULD NOT RESET. DECLARED AN EMERGENCY AND MADE A UNEVENTFUL LANDING. AMBER ICAS (STAB TRIM) AND (MACH TRIM) POST DURING DECENT TO LAND. CREW TRIED TO ENGAGE PITCH TRIM CHANNEL 1 AND 2, DID NOT COME BACK ON LINE DURING FLIGHT. WHILE ON GROUND STAB CHANNELS WOULD RESET. DURING TROUBLESHOOTING, FOUND PITCH TRIM DISCONNECT SWITCH LOCATED IN PILOTS CONTROL WHEEL DEFECTIVE. REPLACED WITH NEW PART, OP'S CHECK OK.