Abstract: A window wiper system for an automotive vehicle provides multiplex encoding of a control switch signal and an additional wiper control signal in a two-channel multiplex control signal and decoding of the multiplex control signal by the wiper mechanism for control of wiper operation. The multiplex control signal is a cyclical waveform containing alternating cycles of different first and second periods wherein the duty cycle of the first period cycles is determined by the additional wiper control signal and the duty cycle of the second period cycles is determined by the control switch. The additional wiper control signal may be derived from a rain sensor, an intermittent delay control resistor or any other device on the passenger side of the vehicle firewall which generates a signal controlling wiper operation.