There are turn signal lights, hazard warning lights, width lights, brake lights, reversing lights, etc. The turn signal lamp is used when the car turns, so that the front and rear vehicles and pedestrians know its driving direction. When the vehicle fails, press the hazard warning light to remind the vehicles behind to avoid. The width indicator light is used to mark the width contour of the car when driving or parking at night.

The brake lights are installed at the back of the car and are used to send light signals to vehicles behind when the car is braking or decelerating to stop, which has warned the following vehicles and pedestrians. The reversing lights are installed at the rear of the car, one on each side. It is used to illuminate the road behind the vehicle and warn vehicles and pedestrians behind the vehicle to indicate that the vehicle is reversing.

The signal light can make other road users at a certain distance clearly recognize the light signal. The related parameters of the light include luminous intensity, luminous area, beam spread angle and light color. In order to easily recognize the light signal at night with a dark background, for signal lights that are only used at night, such as marker lights and parking lights, the luminous intensity is usually only between a few candela and tens of candela. For signal lights used day and night, such as turn signal lights, brake lights, etc., the light intensity required during the day is generally as high as hundreds of candela.