What's the reason for the high beam not working?

[LaRuth]

If the high beam of the headlight is not working, you should check whether the high beam indicator light is on. If it is on, it indicates a fault between the wiring board and the headlight. If it is not on, it indicates a fault between the wiring board and the dimmer switch. Here are some relevant details: 1. Only one headlight is on: If only one headlight is on and the other is not, it may be due to a burnt-out filament, a broken wire, or poor grounding (dim headlight). Some cars have separate fuses for the high and low beams. If the high beam is working but the low beam is not, you may need to check the fuse. 2. How to use the high beam: Generally, it is best not to use the high beam when driving in the city because urban areas usually have good lighting conditions. The high beam angle is too high and can easily dazzle oncoming vehicles and pedestrians, affecting their vision, which is unsafe and considered impolite driving behavior.

[VonValeria]

I just encountered an issue with my high beams not working last month. It was particularly dangerous driving that night. Later, I took it to a repair shop for inspection, and it turned out that the independent fuse for the high beams had blown. Replacing the fuse only cost a few dozen yuan, but the mechanic also reminded me to check if there was any aging or leakage in the wiring. I also learned that in some cars, the high and low beams share the same bulb but have separate circuits, and loose wiring connections can also cause this problem. For self-inspection, you can check if the lighting combination switch has poor contact—this component is often located near the steering wheel and can easily corrode from hand sweat. For older vehicles, another common issue is the alternator voltage being too high, which can burn out the bulbs. My friend’s car actually fell victim to this problem.

[VanArabella]

As someone who tinkers with cars year-round, I've dealt with high beam failures twice. The first time was a burnt-out filament - normal end-of-life for bulbs. The second case was trickier, caused by short-circuiting from damaged wire insulation. My advice: first check the corresponding fuse in the fuse box (location varies by model but typically near the driver's lower left). If the fuse is intact, use a multimeter to test voltage at the switch terminal. Note that many modern cars have auto high beam systems - module faults can also cause issues, requiring a dealership scan tool to read trouble codes. When helping my neighbor diagnose this, we found water damage in the lighting control module caused signal loss.

[SanVanessa]

Having repaired cars for 15 years, high beam failures are all too common. Eighty percent of the time it's due to aging bulbs with broken filaments, while circuit issues account for the remaining twenty percent. If you're handling it yourself, try replacing the bulb first—just make sure not to mix up H1, H7, or other bulb types. When unplugging the connector, check if the copper contacts are oxidized or green, as poor contact is the most annoying issue. If the light still doesn't work after replacement, inspect the 15A fuse in the fuse box. Some cars have their high beam control relay in the engine bay's fuse box—the one making a clicking sound is it. By the way, for cars retrofitted with HID lights, pay extra attention to the ballast; if it fails, it can also cause high beam malfunction.