A B737-700 IN CRUISE AT FL390 DECLARED AN EMER DUE TO RUDDER TRIM TRIMMING OPPOSITE OF INPUT. TRIM L GET R TRIM; WHICH WAS CAUSED BY FAILED CONNECTOR ON TRIM ACTUATOR.

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AT CRUISE ATTEMPTED TO TRIM ACFT WITH R RUDDER TRIM; NO MOVEMENT. PULLED AND RESET CB. SECOND ATTEMPT TO TRIM ACFT RESULTED IN RUDDER TRIM MOVING L WITH R TRIM INPUT. ACFT HAD TWO UNITS OF L RUDDER AT THIS TIME AND UNABLE TO TRIM TO THE R; NECESSITATED MANUAL RUDDER INPUT FOR COORDINATED FLT. PULLED CB; CONFERRED WITH DISPATCH AND MAINT CTL AND DECIDED TO DIVERT TO ZZZ. DECLARED AN EMER; LANDED AT 133000 POUNDS; AN OVERWEIGHT LNDG. NORMAL LNDG AND TAXI TO GATE. LOGBOOK WRITE UPS ON MALFUNCTIONING RUDDER TRIM AND OVERWEIGHT LNDG. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RUDDER TRIM WAS USED AT FL390 AND NO TRIM WAS NOTED AND PER THE BOOK THE CB WAS PULLED AND RESET. THE RUDDER NOW TRIMMED TO THE L WITH R RUDDER INPUT. AN EMER WAS DECLARED AND THE FLT WAS DIVERTED WITH AN OVERWEIGHT LNDG ACCOMPLISHED. MAINT FOUND THE ELECTRICAL CONNECTOR ON THE RUDDER TRIM ACTUATOR HAD FAILED ALLOWING THE PINS TO ARC INTERNALLY. CALLBACK CONVERSATION WITH RPTR ACN 663042 REVEALED THE FOLLOWING INFO: IN CRUISE AT FL390; THE RUDDER TRIM DID NOT OPERATE. THE CB WAS IN AND NOT TRIPPED. THE BREAKER WAS PULLED AND RESET AND THE TRIM WAS OPERATED BUT WITH R TRIM INPUT THE ACTUATOR TRIMMED TO L RUDDER. THE RUDDER TRIM WOULD NOT TRIM R. THE RPTR INDICATED THAT THIS COULD BE A SERIOUS PROBLEM IF THE L ENG WERE TO FAIL.