What is the best way to check if your exterior lights are working?

To check whether the external lights of a car are functioning properly, a combination of visual inspection and functional testing is required. First, conduct an appearance check to ensure that all lamp covers are free from damage, dirt, or yellowing, paying special attention to the light transmittance of the headlights, turn signals, and brake lights. For functional testing, activate each lighting system in sequence: the low-beam headlights should illuminate the road within 10 meters with a horizontal cut-off line to avoid glare; the high-beam headlights need to have clear long-distance penetration; the turn signals should flash at a stable frequency (60-120 times per minute); and the brake lights should respond with high brightness instantly when the pedal is pressed (the brightness should be more than 5 times that of the tail lights). It is best to regularly check the bulb plug connections and fuse status. If abnormal lighting is found (such as one side not working, uneven brightness, or delayed response), it may involve circuit faults or bulb aging, and timely maintenance is required to ensure compliance with safety standards. In addition, fog lights need to be tested separately for their scattering effect in low-visibility environments, while license plate lights should ensure clear visibility at night.