Abstract: A five-switch keypad apparatus having four diodes that multiplex the switch contacts onto three sense terminals. The three sense terminals create a binary code that defines eight possible switch states. The eight states are used to indicate each individual switch closure, a lack of a switch closure, and two simultaneous dual switch closures. In an application, a decoder, connected to the three sense terminals, converts the sequence of binary codes into three control signals. The three control signals can control a door lock, a trunk lock and an automatic lock function.

Abstract: The use of a Gray code ganged wiper switch and an electronic circuit controlling the washer-pump motor and wiper motor allow the use of a minimal number of wires in the overall interval wiper system than found in conventional systems. Circuit redundancy and Gray coding method provides several added reliability features at a low manufacturing cost. The system further provides a resistorless control of the several power output functions of the system.