Abstract: A relay circuit connects the headlight circuit and wiper circuit of a motor vehicle to actuate the low-beam lamps whenever the windshield wipers are activated. The relay circuit includes a delay circuit to permit continuous operation of the headlights even during intermittent operation of the windshield wipers, and an interlock to prevent operation to prevent the low beams and high beams from being simultaneously operated. Further, the relay circuit includes means to prevent operation of the vehicles instrument lights as a warning to the operator.