PURPOSE: To decrease a dark current even at parking by operating only a required minimum part if the operation of a concentrated wiring system such as at parking is undesired and stopping other parts.

CONSTITUTION: Only one of plural terminal stations 10∼14 connecting to a power control switch is selected and operated by a command by a central station 1 at parking. Thus, one of the central station or one of plural terminal stations 10∼14 and one of the central station are operated at parking. While the terminal stations 10∼14 are operated, the center station 1 monitors the power control switch. If some one unlocks a door to open and enters a car, the turning-on of the door switch is sensed by the central station 1 to bring all the terminal stations 10∼14 into the operating state thereby starting the normal operation of the concentrated wiring system. Thus, the dark current at parking is reduced.