A vehicle security system includes a detector circuit cluster, an alarm circuit cluster and a host device, all connected to a common power supply line. The detector circuit cluster includes a detector circuit for detecting a current state of a respective component of the vehicle. The detector circuit can receive a status request signal and transmit a status response signal corresponding to the detected state of the respective component. The alarm circuit cluster is enabled upon receipt of an alarm enable signal for generating an alarm output. The host device can transmit the status request signal for the detector circuit, receive the status response signal from the detector circuit, and selectively transmit the alarm enable signal in accordance with the status response signal.