An elevator system, comprising: an elevator car situated for movement among a plurality of landings, the elevator car including a car door and a door mover; a landing door at each of the landings; a door interlock associated with the landing door at each of the landings, the door interlocks being configured to couple the associated landing door with the car door, the door interlocks respectively including a lock switch; wherein the lock switches are supposed to be in a closed condition when the respective associated landing doors are closed; and the malfunctioning one of the lock switches is in an open condition when the associated landing door is closed prior to the instigated movement of the door interlock; the lock switches are connected in series in an electrically conductive circuit; when any of the lock switches is open the electrically conductive circuit is an open circuit; and a controller configured to: cause the elevator car to move to at least one selected landing of the plurality of landings; when the elevator car is at the at least one selected landing, cause the door mover to instigate movement of the door interlock sufficient to at least temporarily change a position of the lock switch at each of the selected landings; locate the malfunctioning one of the lock switches at one of the selected landings by determining when the electrically conductive circuit changes from an open circuit to a closed circuit responsive to the movement of the door interlock at the one of the selected landings; and characterized in that: the movement of the door interlock is sufficient to cause the malfunctioning lock switch to move into the closed condition; and the controller is configured to locate a malfunctioning one of the lock switches at one of the selected landings based on the movement of the door interlock. an elevator car situated for movement among a plurality of landings, the elevator car including a car door and a door mover; a landing door at each of the landings; a door interlock associated with the landing door at each of the landings, the door interlocks being configured to couple the associated landing door with the car door, the door interlocks respectively including a lock switch; wherein the lock switches are supposed to be in a closed condition when the respective associated landing doors are closed; and the malfunctioning one of the lock switches is in an open condition when the associated landing door is closed prior to the instigated movement of the door interlock; the lock switches are connected in series in an electrically conductive circuit; when any of the lock switches is open the electrically conductive circuit is an open circuit; and a controller configured to: cause the elevator car to move to at least one selected landing of the plurality of landings; when the elevator car is at the at least one selected landing, cause the door mover to instigate movement of the door interlock sufficient to at least temporarily change a position of the lock switch at each of the selected landings; locate the malfunctioning one of the lock switches at one of the selected landings by determining when the electrically conductive circuit changes from an open circuit to a closed circuit responsive to the movement of the door interlock at the one of the selected landings; and characterized in that: the movement of the door interlock is sufficient to cause the malfunctioning lock switch to move into the closed condition; and the controller is configured to locate a malfunctioning one of the lock switches at one of the selected landings based on the movement of the door interlock. cause the elevator car to move to at least one selected landing of the plurality of landings; when the elevator car is at the at least one selected landing, cause the door mover to instigate movement of the door interlock sufficient to at least temporarily change a position of the lock switch at each of the selected landings; locate the malfunctioning one of the lock switches at one of the selected landings by determining when the electrically conductive circuit changes from an open circuit to a closed circuit responsive to the movement of the door interlock at the one of the selected landings; and characterized in that: the movement of the door interlock is sufficient to cause the malfunctioning lock switch to move into the closed condition; and the controller is configured to locate a malfunctioning one of the lock switches at one of the selected landings based on the movement of the door interlock. the movement of the door interlock is sufficient to cause the malfunctioning lock switch to move into the closed condition; and the controller is configured to locate a malfunctioning one of the lock switches at one of the selected landings based on the movement of the door interlock.