If only one of your car’s headlights is dim but steady, the problem is likely uncomplicated and quick to fix. Aging high-voltage halogen headlights are becoming more of a concern for older vehicles.
Burnt Out Bulb
Burnt out, dying, or dim bulbs are the most prevalent cause of malfunctioning headlights. Fortunately, the easiest remedy is also the simplest: just change the bulb. Headlight bulbs, like the H11 LED bulbs in your house, eventually burn out and need to be replaced.
If you often drive at night or keep your headlights on while it’s daylight, you may need to change the bulbs more frequently. Headlight bulbs on older cars that have never been replaced are a potential time bomb.
Lens oxidation
Some motorists may be startled to hear that dimmer headlights aren’t necessarily the result of a burned-out bulb. It’s possible the glasses’ lenses are to fault. Acrylic is commonly used for headlight lenses, the plastic parts that cover the bulbs. Whenever exposed to the sun’s UV rays, this substance undergoes a chemical reaction. Lenses may oxidise over time, giving you a hazy, yellowed, or foggy appearance.
Dirt and Chemical Buildup
In the winter, road de-icer, magnesium chloride, and salt quickly build up, creating a foggy film on the headlight glass. In addition to reducing the driver’s field of vision, this also causes glare for approaching traffic. Spraying cooking oil on grime and film can make cleaning easier. Then, use a powerful detergent and a thorough washing routine to remove the spray.
Bad Ground
If your vehicle’s ground isn’t solid, your headlight’s voltage won’t be high enough to function properly, especially if you use halogen bulbs. A damaged or loose wire, or corroded bulb terminals, might be at blame. You might try cleaning the terminals with a wire brush, or you could just replace the bulb.
Bad Alternator
Headlights that are too weak to see in the dark may also be caused by an alternator that has failed. Lights that flash and dim while the vehicle idles are a clear sign that the alternator needs attention.