Why are my headlights keep dimming

Why are my headlights keep dimming

Headlights, Several topics have been introduced on the headlights. Laser lights, LEDs, Halogens, and HIDs. It is a whole new world of automotive with a variety of options. You will also have one of these headlights installed in front of your car.

With that much complexity of headlights, the chances of defects have also increased dramatically. From the dimming to not working at all. There could be several reasons behind it. If you are the one who is also facing issues with your headlights or maybe you are asking why my headlights keep dimming? Then do not go anywhere. We have a surprise for you. This article will share the most common problems that could occur in your car and how to fix them.

Types of headlight

Before going any further, you have to be clear about the two kinds used in every car.

Single beam

This type of headlight contains only one bulb. The internal technology makes it serve both low beam and high beam purposes. When using the low beam, the low voltage circuit of the bulbs is activated, while on the high beam, the brighter part of the bulb starts glowing.

Dual beam

It is the most common type of headlights in the automotive industry today. Unlike a single beam, the dual-beam has a separate circuit for dim and bright light. When the low beam is ON, The small bulbs with less brightness will glow, But if the road is dark or the visibility is poor, and you have decided to go for a high beam, the car will activate the high-intensity bulb circuit to assist you in seeing things far ahead.

Now you know about the two basic types of headlights. It will help you a lot in the diagnosing process. You can now predict which bulb is malfunctioning by analyzing your low beam and high beams.

Since you have gone through the basic information, You can now confidently jump into the diagnosing phase. Here I will discuss the five most common causes that result in the dimming of headlights.

The five defects are:

  • Oxidized Plastic
  • Weak Bulb
  • Bad Generator
  • Poor Alignment
  • Corroded Wires

Oxidized plastic

Oxidized Plastic

First and foremost is to check your headlight condition. It occurs in almost 99% of vehicles. The poorly maintained headlights get oxidized over time. Unlike glass, plastic is more sensitive to UV and requires special treatment and precautions to keep it glowing like brand new. To check the above defect, simply go to the front of your car and analyze the outer layer of headlights. Is it completely visible from inside, or is there a cloudy rough plastic that limits your view?


If you find that your car headlights are foggy or cloudy. Then it’s a sign of poorly cared headlights. You are left with two options here. Either go for a new one. But it will cost you huge money and they will also go foggy over time. The second one is the most reliable way. Just buy a headlight restoration kit, This kit has a special formula in it. It will restore your headlights to brand new condition. You will love that kit.

Weak bulb

Weak car Bulb

The second step that comes to your checklist is to test the weak bulb. Headlight bulbs do get weak over time and become dull. So it is a good idea to have them check before they completely go off


Unfortunately, there is no professional tool to check your headlight bulbs. So the only option you are left with is either buy new bulbs for your car or take your car to a shop to have them checked. The mechanics will have spare bulbs in their shop and he will check by replacing bulbs from your car.

Bad generator

Bad generator

Do you know electricity is more important than fuel in your car? Most people believe that if the car has fuel, it will run fine. And this is true but, electricity matters a lot in your car. From your ECU to the glowing spark plugs everything is working on electricity. Without electricity, your car can’t even run a 1 mile easily. So the question is where does all this electricity come from. The answer is from your car alternator. It is part of your car that is run by the serpentine belt. This works like a turbine and produces electricity when rotated. If the alternator goes bad. All of your car’s electric parts will be compromised including the headlights.


Check your car headlights by parking your car in front of the wall. It’s better to do this test at night. Once you have parked it. Put your car in neutral. Obviously, you don’t want to hit the wall. From this position turn on your car headlights and give some gas. If your headlight brightness remains the same then you got a good alternator. But if you notice that your car headlight brightness increases when you give the gas and then decreases then it’s a sign of a bad alternator. In that case, replacing the alternator is the only option you have.

Poor headlight alignment

Poor headlight alignment

We have discussed it several times before. Poor alignment can also be a cause of your headlight’s dimming. If your headlights are not aligned properly. Then it doesn’t matter how bright your car headlights are, you will suffer. Since they will focus more on the sky or below the car. You will find it difficult to see things upfront.


In the above scenario, you can align your headlights by taking them to your local auto shop. OR you can do it by yourself. There are a number of articles present on our blog on how to align your car headlights. This topic will help you align your car at home with minimum tools.

Corroded wires

Corroded wires

Last but not least. The corroded wire could be the reason behind the dimming of headlights. Try to disconnect all the harnesses and then reinstall them. Due to corrosion build up over time. The electrical supply would be compromised and you will end up in a poor or dim headlight.


There are several electrical cleaning sprays present in the market. Use one of them to clean your harness. Simply spray them in the electrical harness and everything shall be cleaned.

These were the top defects that happen most of the time with car guys and the list doesn’t end here, several problems could occur. If these problems don’t fix your issue or you still want to learn more about your headlights then visit https://headlightrestore.us/blog/. There you will find several blogs to fix your car problems.

Oxidation is the issue that happens with every car, you can’t avoid it. The only thing you can do is to keep them in control. Just visit the site https://headlightrestore.us/. There you can find a headlight restoration kit that can clean your car’s headlights In less than 15 minutes of work. This will make your car headlights look brand new.

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