Abstract: An anti-theft system for an automobile includes a microprocessor-based control module that enables operation of solenoids for the power circuits of the car only if a proper identification code is entered by a data entry device and the automobile's ignition switch is sequenced through its positions. The anti-theft device further includes operating a serial switch placed in a critical electrical circuit for the engine, and data communications capability with electronic controls for the engine and other systems on the automobile so as to limit or to disable their function.

Abstract: An electronic lock security system includes a coded key and a multiple position key receiver switch having a code sensing circuit for generating signals indicative of the key's code. A decoder compares the key's code to a preset code and when a match is determined outputs a control code to a switch control circuit. A switch control circuit includes flip-flops for remembering when switch positions intermediate the off and last positions have been accessed and output control signals upon receipt of the decoder's control signal. The flip-flop outputs are consecutively ANDed together down to the last position to permit operation of a power switch to provide working power to a solenoid operated device only when all positions of the multiple key receiver have been accessed during operation.