In life, car owners mostly check the burn out of lamps and lanterns outside the car. But we have no idea how to maintain the overall system of lamps outside the vehicle. In fact, it is very important to maintain the outside lamps and lanterns in time. This not only affects the comfort, but also directly relates to the safety of driving. Usually, before being reminded, it is difficult for owners to realize that headlights, taillights, turn signals or stationing are no longer working properly. In more cases, the fault of the vehicle lamp is not limited to the small problems such as the bulb burning, the corrosion of the socket or the damage of the plug. It is often necessary to take professional diagnostic techniques to analyze the root cause of the failure. Even in those low priced cars, the internal and external lamps are controlled by the main computer, and those luxury cars are controlled by 3 computers only. If a car is equipped with a daily line DRLs (DaytimeRunningLamps), you must first understand how these devices work. For example, some daily line lights are not open before the engine starts, and there are some daily lines. If the car has not been cancelled, even if the engine has been started, its daily line is still not working. If the vehicle is equipped with a light control lamp (that is, when the outside light is dim to a certain degree, the system has the function of the headlight before automatic opening), it may be useful to check the working condition of the light from the weakest to the strongest state, and of course not ignore the inspection of the automatic closing timer. If the system is equipped with a timer, please set it to the maximum delay. If the headlamps are damaged, they are usually replaced by similar lamps and lanterns. Some cars are equipped with high-intensity discharge headlights HID, which generate high-density light sources through high-voltage arc discharge produced by their pre designed electronic system. Note that ordinary quartz halogen bulbs can not be used here. In addition, it is also necessary to check whether there is a crack in the headlight lens, because the surface cracks will not affect the lighting performance of the headlights, but the moisture will seep into the lamps and lanterns along the cracks, which will reduce the service life of the bulb. The calibration of the light direction of the headlights should also be included in the maintenance list, because in order to ensure the maximum safety of the driver, the headlights must be able to provide good forward lighting for the driving vehicle. In addition, many vehicles also use fog lamps as standard equipment or popular selection, and the fog lamps are usually installed in the lower position of the car, so it is very vulnerable to the damage of the stone. In the maintenance, the cracks in the lamp lens should not be ignored except for the inspection of the lighting system itself.