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Why is One Headlight Dim and the Other Bright?

Why is One Headlight Dim and the Other Bright?

Headlights are an essential component of vehicles because they provide illumination to see the road clearly. It can also make driving safer at night by preventing collisions with other vehicles and potholes.

Why is One Headlight Dim and the Other Bright? Sometimes one headlight is dim, and the other is bright due to deterioration of the clear coat and oxidation of plastic material giving a cloudy appearance. One headlight becomes dim because bulbs are blown out when they become old. The faulty wiring, loose connections, and accumulation of metallic filament in the bulb due to overheating will also blur its lens. The improper installation of headlights, corroded ground wiring, and gas accumulation in the bulb can also cause this issue. Sometimes right side headlight seems brighter because of its slightly higher installation than the left side.

When you feel one side got dim, it is necessary to check the problem. You cannot drive with blur headlights because they can cause severe highway accidents.

Damaged plastic coating

The headlights of the trucks are coated with plastic material to make them clear. This coat is also known as a clear coat, necessary for efficiently passing the light to the outside.

When this clear coat becomes damaged, the plastic on the lens also starts to deteriorate, which can make one side dim.

The deterioration of clear coats becomes a common issue when you park your vehicle outside. This is because the UV radiation from the sun damages the plastic coating.

Moreover, exposure to high temperatures during driving will also cause this problem. When you stay for a longer time in the rain, this clear coating also starts to come out.

You cannot drive appropriately in this situation because cloudiness and fogginess come on the lens, making the vision blur.

Due to the oxidation of plastic material, the lens becomes yellowed and dims the lights, eventually making them blur.

You can fix it by parking your vehicle in shady areas during the daytime to prevent them from the direct heat of sunlight.

Old bulb

The bulbs are also present in the headlights, which are essential for providing light. In addition, these bulbs are helpful to illuminate the road for safe driving at night time.

These bulbs spread light in all directions with the help of a lens that refracts the light. Sometimes one of the bulbs becomes faulty and unable to perform its function.

These bulbs have a specific life span, after which they become faulty and dim the lights. Moreover, any fuse and module issue will also dim the headlights.

The old-age bulb cannot perform its function well and cannot provide adequate illumination for safe driving on the roads.

Sometimes the bulb of one side becomes faulty compared to the other side, making one side brighter and the other side dim.

The life of these bulbs will also decrease when you drive at night for a longer time and turn them on during a full day.

You can resolve this issue by changing the bulb on both sides so it can provide equal illumination.

Issues with wiring

The wiring is the major component of the vehicle to provide electricity to different components.

For example, both sides of the headlights are appropriately connected with wires for proper illumination and functioning.

Any issue with the wiring system makes one side brighter than the other. For example, one side becomes dim because of a fault in its wiring system.

There is a problem with their connections that become loose and cause a flickering and dimming issue. In addition, the short circuit will also produce at one side, which can cause the fuse to blow out.

The blown-out fuse will make the lights on one side dim more than the other. Furthermore, the damage and wear and tear in wires will also cause this issue.

It is necessary to resolve this issue with the wiring system for smooth and comfortable driving during night hours.

Check all the wiring connections on the dim side to fix the problem when you feel that one side is brighter than the other.

Accumulation of filament

The filament is the necessary part of the headlights to illuminate them. These filaments also produce more heat inside the bulb, which can also cause their burning.

The uneven power supply from the battery sources can cause the burning of filaments on the inside of the bulb.

In addition, continuous driving on bumpy roads and hitting potholes also cause a problem in these parts.

When these filaments vaporize, it can cause an accumulation of gray and brown metallic-like material on the interior side.

The accumulation of this metallic material resists the pathway of the light. The resistance in light passing will make one light dim than the other.

When you turn on the headlights on a longer trip, the tungsten filament becomes overheated, and metallic material deposits on the sides.

You can increase filament life by reducing driving on the uneven road surface to decrease the vibrations.

It is also necessary to change the whole bulb in this situation for clear vision on the roads.

Depending on the type of headlight bulb 

Many people complain that one side of the headlight is brighter than the other. This situation also depends upon the type and quality of the bulb.

The issue is most common in Xenon HID types which can cause dimming of one side headlights. The dimming of a side is problematic when driving a vehicle on highways.

The problem mainly occurs in this type because the life of their bulb is less than in other types.

Most of my friends who used the lights from this company complain that one side becomes dim after some years.

The diming on one side commonly occurs due to blowing out of the fuse and another issue.

The headlights are the aftermarket product that you can replace according to your choice. It is better to purchase the ones that have more durability.

Misalignment of headlights

The proper alignment of these components is also essential for their appropriate functioning.

Sometimes, people change them and add new headlights according to their requirements. Then, they complain that one side of the headlight is brighter than the other.

The issue most commonly occurs due to their improper installation and poor alignment. You also have to add the new ones if the old ones get damaged due to accidents.

The collision with road hurdles and other vehicles can sometimes cause cracks and breakage.

You can fix it by taking service from the expert mechanic for its proper installation and appropriate alignment in the right place.

Accumulation of gas inside the bulb

The bulbs of the headlights also have xenon or argon gas for their longevity and proper functioning. These gases are essential to prevent the tungsten filament from oxidation.

It will also prevent the overheating in filament and also reduces their evaporation. Sometimes, this gas starts to come out and form a layer on the sides of the bulb due to some reasons.

The accumulation of this gas at one side makes the bulb dim and causes a hindrance to light to escape.

Due to this gas layer, you feel that one side is brighter, and the other side is a blur.

Issues with ground wire

The ground wire is also the primary component for working of headlights in trucks. These wires are essential to connect them with the chassis structure.

In addition, these are the part of an electrical circuit for the proper flow of electricity through them.

When these wires become damaged, enough electricity cannot come towards headlights, and they become dim.

Each side has its connectivity with ground wires, and issues with these wires make one side brighter than the other.

Sometimes the ground wires at one side become corrupted due to dirt, dust, and any leakage material.

They cannot provide the appropriate electricity supply to this site which can cause dimming.

However, you can quickly call the mechanic to replace the ground wire on the effective side to fix the problem.

Poor supply of battery

The battery is the component of the pickup truck that supplies power supply to a different component.

It supplies power to turn on the headlights and supplies electricity to other dashboard components.

Sometimes battery becomes faulty due to old age, which can cause an interruption in the power supply to the bulb.

The faults in the battery will also cut down the power supply to one side, making this side dim than the other.

The presence of corrosion in its terminals and decreased fluid will also cause malfunctioning of batteries, and they cannot supply power to run different systems.

You can replace the batteries in case of complete damage or clean the corrosion from its terminals for the proper illumination of bulbs during driving.

Accumulation of dirt and condensation

The dirt is also the major component that can cause the dimming of one-side headlights. Sometimes the cracks on one side will cause an accumulation of dust and dirt.

The dust will form a layer and block the passage of light to come outside.

Moreover, the condensation process in headlights is also common, which can blur the lens and make one side brighter.

The condensation process occurs due to faulty exhaust fans and causes moisture to accumulate on the interior side.

When the plastic of these headlights is cool while the temperature on the inner side is high, it will also cause moisture droplets to come inside.

The condensation at one side lens will cause issues and make them dim than the other ones. You can easily fix this problem by unscrewing them and wiping their surface with a lint-free cloth.

Why does it seem like one headlight is brighter than the other?

Some people complain that one side of their headlights is brighter than the other. They also said that the right side is a brighter one as compared to the left side.

 There are issues with their alignment; the headlight is slightly higher on the right side to see a clear picture on the side of the roads.

The left side is slightly lower, so people coming in front of you cannot face the issue of blur vision. In this way, the higher side that is the right one seems brighter than the lower one.

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