Patent attributes
On condition that a holder of a portable device has manipulated an ignition switch, a main control ECU discriminates the open/closed state of a luggage compartment door. When the luggage compartment door is in the closed state, the main control ECU instructs a rear transmitter to transmit a first request signal. When the luggage compartment door is in the open state, the main control ECU instructs the rear transmitter to transmit a second request signal. A portable ECU discriminates the request signal received by a receiver. When the received request signal has been determined to be the second request signal, the portable ECU adjusts the transmission output of a response signal which is to be transmitted from a transmitter, to a second transmission output which is lower than an ordinary output.
