Vehicle anti-theft system

Abstract

A vehicle anti-theft system in which, only when the ID signal is obtained from a right ignition key and when the vehicle anti-theft function is halted by the failure of an anti-theft circuit or theft detection unit itself, the start-up of the engine is permitted. The system comprises a unit for generating a start-up enable signal in response to a verification signal representing a right ID signal, and an engine control unit for performing the start-up control of the engine in response to the start-up enable signal and disabling the engine in response to a theft signal. The start-up enable signal generating unit generates a start-up enable signal in response to the fault signal. A dummy line for detecting a breakage is wired along various signal lines wired on the substrate of an immobilizer, which, if intentionally broken by an ill-intentioned third party, could cause a fault signal similar to that for the failure of the immobilizer to be outputted from a determination signal output terminal. If a break in the dummy line is detected, the engine control is inhibited even if the fault signal is detected.