It is a fast and simple work to check the burning defect of the lamp bulb outside the vehicle, but the maintenance of the overall system of the lamp outside the vehicle is not so simple. Timely maintenance of outside lamps is very important for drivers, because it not only affects the warmth of driving, but also directly affects the safety of driving. Usually, before being prompted, it is difficult for car owners to realize that the headlights, taillights, turn signals or parking lights have not worked properly. By the way, it's very easy to replace a burnt out light bulb, and the cost of DIY is lower than the charging standard for stopping the maintenance of lighting system at the repair station. In more cases, the defects of lamps are not limited to the small problems such as bulb burning, socket corrosion or plug damage. It is often necessary to adopt professional diagnostic technology to analyze the basic causes of defects. Even for low-cost cars, the interior and exterior lights are controlled by the main computer. And those luxury cars, only their headlights are controlled by three computers. Assuming that the car is equipped with DRL, you must first understand how these installations work. For example, some of the daily running lights can not be turned on before the starter is started, and some of the daily running lights can not work normally even though the starter has been started, assuming that the parking brake has not been cancelled. Assuming that the vehicle is equipped with light control lamp), it's OK to check the working condition of the lamp in the process of light sensitivity from the weakest to the strongest. Of course, don't neglect to check the automatic off timer. Suppose the system is equipped with a timer, set it to the maximum delay. If the headlamp is damaged, it is usually replaced by a similar lamp. Some cars are equipped with high-intensity discharge headlight hid, which generates high-density light source by high-voltage arc discharge generated by its pre designed electronic system. Note that ordinary quartz halogen bulbs cannot be used here. In addition, we should also check whether there are cracks in the headlamp. Although the appearance cracks will not affect the lighting performance of the headlamp, moisture will penetrate into the lamp along the cracks, which will reduce the service life of the bulb. The calibration of headlamp lighting direction should also be included in the list of maintenance items. In order to ensure the maximum safety of driving, the headlamp must be able to provide good forward lighting for driving vehicles. While grasping the key, we must not forget to inspect other lamp systems, such as turn signal, license plate lamp, side lamp, parking lamp, reversing lamp and brake lamp. In addition, many vehicles also use the fog lamp as a standard or popular option. The fog lamp is usually installed at a lower position on the vehicle, so it is vulnerable to damage by stones. When maintaining the middle of the car, in addition to checking the lighting system itself, the cracks of the lamp should not be ignored.