Electronic flasher unit for vehicle lighting system and method of

Abstract

A method and an electronic circuit are for monitoring the operation of a circuit including a plurality of intermittently powered parallel load elements, such as the flasher lamps of a vehicle. The total load current is directed through a measuring shunt resistor, and the resulting voltage across the shunt is measured and evaluated. The measured voltage initially arising across the shunt is used as a basis to establish a first voltage level for a load failure control threshold. A second voltage level greater than the first voltage level is established as a short-circuit control threshold. Then, the voltage value arising across the shunt during operation of the circuit is compared to the load failure control threshold and the short-circuit control threshold, and a load failure or a short-circuit is detected dependent upon and responsive to the result of these comparisons. If the measured voltage exceeds the first voltage threshold but not the short-circuit control threshold, then a higher voltage level is established as the load failure control threshold. The method and circuit arrangement are self-evaluating and self-adapting for different current flow conditions, and are suitable for use in a variety of load circuits, particularly a variety of different vehicle flasher light system configurations.