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5 Illuminating Reasons for Dim Headlights (+ Possible Fixes)

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Do you have trouble seeing while driving at night, even after turning on the headlight switch?
Well, time to see your optometrist. No, seriously, consider it. 

Is your eyesight good? Then you might have dim headlights. 

In this article, we’ll discuss five reasons why you have dim headlights, five possible fixes for dim headlights, explore the difference between LEDs and incandescent bulbs, and answer four dim headlight FAQs

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Let’s get started.

5 Reasons Why You Have Dim Headlights

Here’s a list of five reasons behind dim headlights:

1. Burnt Out Bulb

Dim, dying, or burnt-out bulbs are often the most common culprits. Thankfully, they come with the simple solution of bulb replacement.

Like your home light bulb, your headlight bulb requires replacing after some time. If you’re a driver that leaves their headlights on during the day or regularly drives at night, you’ll have to replace your bulbs more frequently.   

Note: Don’t forget to turn your headlights off when you exit your car — or your battery will drain!

Older vehicles are also at higher risk for burnt-out bulbs, especially if they’ve never had bulb replacements. 

2. Headlight Lens Oxidation

Your lenses— the plastic pieces covering your bulbs— might cause a dimmer light output.

Headlight lenses are often made of acrylic, which will react to the sun’s UV rays with prolonged exposure. The reaction causes the lenses to become oxidized, leading to a foggy, cloudy, or yellowed lens.

What’s this got to do with dim headlights?
The opaque shade of the headlight lens doesn’t let as much light pass through as a clear lens would. As a result, you’ll still experience dim light, even if you’ve just replaced your bulbs. 

Call your mechanic for a lens restoration service. An experienced mechanic will use professional tools to restore your lenses and protect your headlamps.

3. Electrical Issues or Wiring Troubles

When you turn on your headlight switch, certain electrical system components, like a wiring harness and fuses, help deliver power to your headlights. Wiring troubles are rare, but you should still check it. Wiring issues can limit your light output, making the light dimmer or non-existent. 

Note: Halogen lights are particularly affected by bad ground wires. However, dealing with wiring can be complex and may cause issues if you’re inexperienced and attempt DIY repairs. 

4. Your Headlight Settings

Modern vehicles often have different lighting options, so check your headlight settings if they seem dim or have stopped working. 

Additionally, there are adaptive headlight settings— which many drivers forget about. Always check your settings after an accidental bump or someone else has driven your car, as this might be why your settings are different.

One more thing— sometimes you might just be using fog lights instead of your standard headlights. If your fog lights are on, a simple setting adjustment can rectify your dim headlights. 

5. Bad Alternator

When experiencing dim headlights, you should check for a dying alternator. Especially if you notice your car lights brighten and dim as the engine revs. However, with a broken alternator, dim car lights will be the least of your problems. A bad alternator could completely drain your battery.

How?
Your car will draw all its power from the battery, and the battery won’t be recharged. 

Since we’ve identified the culprits responsible for dim headlights, let’s discuss some possible solutions you could consider when treating it. 

5 Possible Solutions to Your Dim Headlights

Here’s what you can do to improve your dim headlight situation:

1. Replace Your Bulbs

Halogen and HID bulbs get dimmer over time. But remember, if your car originally came with the basic halogen bulb, that doesn’t mean you have to replace it with the same bulb. There are different light bulb options if you decide to switch. 

Here’s a list of some headlight bulbs and how long they last:

Check your headlight housing unit and connector for any damage when replacing the headlight bulb.

2. Polish or Replace Your Lenses

If you’re the DIY type and have time, you can polish your own headlamps. 

Tip: Use toothpaste or a scratch remover to bring a clear shine back to your dull plastic headlamp cover.

If you’re not a DIY fan, many body shops and mobile mechanics also offer a headlight polishing service. 

A refurbished headlight lens isn’t a bad quick fix, but remember, new parts will stay in peak condition for longer. With a new light, you could avoid more expensive repairs along the way— like the potential costs related to an accident (just because you couldn’t see clearly).  

3. Repair the Corroded Wires

This repair will depend on the exact nature of your wiring issues. Depending on the faulty electrical component, you’ll require a wiring adjustment, a new wiring harness, a replacement fuse, or some other electrical system repair.

Your wire components can also rust over time. 
Luckily, if you have a wire brush, there’s a simple fix:

  1. Disassemble your dim headlights.
  2. Inspect the wiring harness and headlight connector to find rust.
  3. Use a wire brush to clean the ground wire connection.
  4. Apply dielectric grease to the cleaned ground wire.
  5. Complete the headlight assembly and then check the brightness.

You could also work with your mechanic to properly diagnose the problem and create a repair plan. 

4. Fix Your Faulty Alternator

You have three options when it comes to dealing with a dying alternator. 
You can:

Remember that the above suggestions depend on how badly your alternator is damaged. 

5. Look After Your Windshield

This might seem like an odd suggestion since it won’t really do anything for your dim headlights, but a clear and uncracked windshield makes it easier to see at night. 

Dirty, damaged, and old windshields can obstruct your night vision. So it’s best to sort out those tiny cracks ASAP before they become a bigger nuisance. 

Want to know why some vehicles have blinding headlights, and others are barely visible? 
It basically depends on the type of bulb used. Let’s learn more about LEDs and incandescent bulbs. 

LEDs vs. Incandescent Bulbs: What’s the Difference?

If you’re driving with traditional incandescent headlight bulbs, you might think your headlights seem dim compared to someone using LED bulbs. 

Why’s that?
Traditional halogen headlights emit a softer, warmer, yellowish hue, while LEDs produce bright white light with bluish tones. The color of the LED is harsher on the eyes and has a more intense contrast with the darkness. As such, although halogen and LED headlights produce the same amount of light, LEDs seem like brighter headlights.

The brightness of your headlights also depends on other factors, like the make and model of your vehicle, your lenses, your headlight shape, etc.

Want to switch to LEDs?
You’ll need to consider the pros and cons. LEDs aren’t the only other bulb option available for your vehicle. Speak to your mechanic about if you are interested in brighter bulbs. 

Now let’s shed some light on a few dim headlight FAQs.

4 FAQs On Dim Headlights

Here are the answers to four questions regarding headlights:

1. What Causes Headlights to Dim and Brighten While Driving?

If your car lights flicker and dim while driving, you could have a faulty alternator.
Your alternator feeds electricity to your lights while your engine runs. When your engine isn’t running, your lights rely on your battery for power. 

If you notice your lights dimming and flickering at low revs, your battery might be the issue.

2. How Do I Know My Headlights Are Too Dim?

According to the National Highway Traffic Safety Administration (NHTSA), if your headlights aren’t shining as far as 160 feet, they’re too dim.

If oncoming vehicles are flashing at you even though your headlights are on, they’re too dim. 

3. Why Do We Dim Headlights at Night?

Driving past someone with blinding lights sure is frustrating.

Like how hard is it to reach for the dimmer switch?
However, sometimes the driver might have their regular headlights on, but LEDs could make it seem like brighter headlights.

All drivers should know to reach for their dimmer switch and not to use their brights when there are oncoming cars at night. It’s standard practice to be mindful of other drivers. Dimming your headlights at night is just one way to do so. 

4. How Can I Tell If My Headlight Fuse is Blown?

Fuses protect every electrical component, and your lights will stop working if the headlamp fuse blows.

However, if your low beam is okay, but the high beam isn’t, there’s probably an issue with the relay that controls them. To narrow down the relay problem, you can check the fuse wire.

Wrapping Up

Dim headlights might not seem like a significant issue, but they can cause some major repercussions. It’s better to invest in some quality lights before it’s too late. 

To ensure professional vehicle repairs and maintenance, why not get the help of the experts at RepairSmith

You can easily book RepairSmith’s mobile mechanic service using the online booking option. All repairs come with a 12 month / 12,000 mile warranty and are done in your driveway! 

Contact us today for assistance with any car-related electrical issues.