Abstract: A double relay control circuit for connection between the ignition switch and starter switch of a vehicle and the vehicle power supply and exterior lights for providing automatic daytime running lights whenever the vehicle ignition switch is ON and the starter switch is OFF and subject to being overridden by the conventional light switches and ambient condition and vehicle condition sensors.

Abstract: Relay switching circuits for supplying power to a vehicle exterior lighting system to provide for daytime running lights and which are controlled by solid state logic circuits, depending upon the condition of either or both of the vehicle starter and ignition switches.

Abstract: An automated daytime running light system for surface transport vehicles having headlights and taillights which includes a daytime running light control circuit which activates the highbeam filament of the headlights at a reduced power level whenever the vehicle ignition is ON and the starter motor OFF during daylight conditions. In one embodiment, the daytime running light control circuit activates the high beam filaments of the headlight at a reduced power level and also activates the parking lights to provide taillights whenever the vehicle ignition is ON and the starter motor OFF during daylight conditions.

Abstract: An automatic daytime running light system for a vehicle having an engine, an electric power source, a starter motor circuit for the engine, external running lights including headlights and parking lights, and input switches for ignition circuit and the external running lights, the system being responsive to the input switches and starter motor circuit to automatically control the operation of the external running lights, and the system including digital logic timer circuit means for automatically controlling the operation of the external running lights, and MOSFET output switching devices, which thereby provide high reliability and safety, redundant circuitry to thereby provide a higher level of reliability and fail-safe operation of the system, and MOSFET fault current monitoring circuitry which monitors the drain to source fault currents of the MOSFET output switch means, whereby upon detection of fault currents, the digital logic timer controls a fault current indicator to provide an indication of a fault