Hazard Light flashers
Also called "hazards", "hazard warning flashers", "hazard warning lights", "4-way flashers", or simply "flashers".
International regulations require vehicles to be equipped with a control which, when activated, flashes the left and right directional signals, front and rear, all at the same time and in phase. This function is meant to indicate a hazard such as a vehicle stopped in or near moving traffic, a disabled vehicle, a vehicle moving substantially slower than the flow of traffic such as a truck climbing a steep grade, or the presence of stopped or slow traffic ahead on a high speed road.
Sometimes, they are used in severe fog conditions.Operation of the hazard flashers must be from a control independent of the turn signal control, and an audiovisual tell-tale must be provided to the driver. In vehicles with a separate left and right green turn signal tell-tale on the dashboard, both left and right indicators may flash to provide visual indication of the hazard flashers' operation. In vehicles with a single green turn signal tell-tale on the dashboard, a separate red tell-tale must be provided for hazard flasher indication.
Because the hazard flasher function operates the vehicle's left and right turn signals, a left or a right turn signal function cannot be provided while the hazard flashers are operating