Abstract: A vehicular hazard warning system has an indicator on the vehicle that is energizable to yield a warning signal. The onset of a hazardous condition is detected and, as a result, a control signal is developed which has a variable parameter the amount of which is proportional to the degree of hazard represented by the condition. In response to that condition, the indicator is energized in a manner which quantitatively has a magnitude that is proportional to the amount of hazard. The system primarily responds to abrupt deceleration. It also preferably is responsive to such other inputs as brake pressure, wheel speed change, inertial forces and operator-controlled pedal movement.