Load type electrical parts incorporated in auxiliary machine modules 164a to 184a are driven by electrical connectors 160a to 180a having communicating units, control units and load driving units mounted on electronic boards. An electronic door control unit 200a connected to a sub bus connected to the electrical connectors 160a to 180a converts the communication protocol of a control signal of the load type electrical parts received from a LAN in a vehicle serving as a main bus of the vehicle to the communication protocol of the sub bus and transmits the protocol converted control signal to the electrical connectors 160a to 180a. Further, sensors or switches in the auxiliary machine modules 164a to 184a output signals to the control units.