Passive keyless entry device for monitoring tire pneumatic pressure by bidirectional communication

A passive keyless entry device for monitoring a tire pneumatic pressure by bidirectional communication comprises:

• a car mounting device mounted to an automobile;
• a keyless entry portable device;
• and
• a transmitter-receiver for monitoring the tire pneumatic pressure,
• wherein said car mounting device comprises a low frequency signal transmitting section for transmitting a request signal of a low frequency to said keyless entry portable device and said transmitter-receiver for monitoring the tire pneumatic pressure, a receiving section for a keyless entry for receiving an answer signal of a high frequency responsive to said request signal from said keyless entry portable device, a receiving section for monitoring the tire pneumatic pressure for receiving the answer signal of the high frequency responsive to said request signal from said transmitter-receiver for monitoring the tire pneumatic pressure, and a controller for forming said request signal and controlling operation of a door lock mechanism in response to said answer signal and obtaining tire pneumatic pressure information.