ISO symbol for hazard lamps
Also called "hazards", "hazard warning flashers", "hazard warning lights", "emergency 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.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.
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.
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 may not be provided while the hazard flashers are operating, although the vehicle may activate the indicator and return to the hazard flashing phase once the indicator is deactivated.