Whether you’re driving at night, in the rain, in the fog or snow, having working headlights is absolutely essential. They provide light so you can see where you’re going, but they also help alert other drivers to your presence, enhancing the safety of everyone you encounter on the road. If your headlights seem dim, there may actually be an underlying problem that needs to be corrected.
How this system works:
No matter what type of bulbs you’re using, the system works in the same basic way. Your headlights are connected to the engine wiring harness via connectors, and they’re grounded to the chassis of your car (without a ground, they won’t work).
When you turn on the headlight switch, power is sent from the battery/alternator to the bulbs, causing the filaments to heat up and glow, which produces the light you need to see the road. They work just like the light bulbs in your home – a broken filament, or anything that disrupts the flow of electricity through the circuit can cause problems.
However, bulbs are a lot like fuses in that they either work or they don’t work. That means if your bulbs are dimmer than normal, the problem isn’t likely in the bulb itself, but somewhere in the wiring leading to the bulbs.
Common reasons for this to happen:
Corroded Ground Wire: One of the most common causes of dim headlights is a corroded ground wire. Ground wires connect the bulb circuit to your car’s chassis (which serves as the ground itself). If corrosion develops on the wire (or the connection is dirty or damaged), it disrupts the flow of electricity, often enough to limit the output of your bulbs.
Discoloring Deposits: This is particularly common with halogen type light bulbs. Over time, the inert gas within the halogen bulb creates a discoloring film (brown or gray). This builds up on the inside of the bulb and dims the light output. Replacing the bulb is generally the only option here.
Bad Alternator: Another very common reason to see dim headlights is a failing alternator. If you notice that the lights brighten and dim as the engine revs up and down, the alternator should be checked immediately. If it fails, dim lights will be the least of your problems. The car will begin pulling power from the battery and because it’s not being recharged, it will eventually drain completely. This will leave you stuck on the side of the road.
Yellowed Lenses: Often, dim lights have nothing to do with the flow of electricity or aging bulbs. Rather, they have to do with the aging of the headlight lens (the large plastic cover that protects the bulbs inside). Lenses yellow as they age, and this affects the amount of light that can escape and limits your visibility at night.
Loose Alternator Belt: Dimming lights may not be a sign of a bad alternator. It might be a loose alternator belt instead. If the alternator belt is loose, it doesn’t turn the pulley correctly (it slips and then grabs, slips and then grabs). This can be noticed in dimming and brightening headlights. The belt should be checked for excess play, as well as wear and tear.
What to expect:
A top-rated mobile mechanic will come to your home or office. The mechanic will inspect the headlights, the wiring harness, the ground wires and other components. The mechanic will then provide a detailed inspection report that includes the scope and cost of the necessary repairs.
How it's done:
The mechanic will inspect all parts of the headlight system, including the lenses, the bulbs, the wiring connectors, the ground wires and more. It may be necessary to perform a charging system test to determine if your alternator is healthy. The mechanic may also need to check the alternator belt.
How important is this service?
If your headlights are dim, it could be a sign of a serious underlying problem. Even if the issue is something as simple as a corroded ground wire, your safety is still compromised because you don’t have adequate visibility at night and while driving in inclement weather. One of our professional mechanics can inspect your headlights and determine the cause.