Abstract: An anti-theft device for automobile vehicles disables the vehicle's starter ignition system unless a coded resistive element is inserted into the device by the vehicle's operator. A control system senses the value of the coded resistive element and enables the starter system if the sensed value is correct. A latching circuit latches-in enablement of the starter system after an arming switch is activated and the resistive element has been removed, serving to provide a valet function. A lock-out circuit prevents enablement of the starter system for a prescribed time period following an unauthorized attempt at enabling the system, as when an incorrect resistive element is inserted into the device. The device employs a normally closed relay to enable the starter system so that failure of those portions of the device which are most likely to fall does not affect normal operation of the starter system.

Abstract: An anti-theft device for automobile vehicles disables the vehicle's starter ignition system unless a coded resistive element is inserted into the device by the vehicle's operator. A control system senses the value of the coded resistive element and enables the starter system if the sensed value is correct. A latching circuit latches-in enablement of the starter system after an arming switch is activated and the resistive element has been removed, serving to provide a valet function. A lock-out circuit prevents enablement of the starter system for a prescribed time period following an unauthorized attempt at enabling the system, as when an incorrect resistive element is inserted into the device. The device employs a normally closed relay to enable the starter system so that failure of those portions of the device which are most likely to fail does not affect normal operation of the starter system.