My Headlights Turn Off While Driving – What Are Causes And Solutions?


The headlight system is usually not overly complicated and consists of a few basic components such as a bulb, relay, fuse, and switch. Thus, when they fail, it could be due to these components.

If you wonder, “Why do my headlights turn off while driving?” then this article is exactly for you. Please keep reading to find out the causes and the way to fix them!

What Causes My Headlights Turn Off While Driving?

Headlights are necessary for low light condition driving (Source: DLAA Foglight)

One Bulb Is On

It is a case when one side burnt out while the other is still working well. Normally, each headlight has an operating life, and when this threshold is reached, you should replace them. The long-life is based on each type of bulb, such as:

  • Halogen: 450 – 1000 hours (usually 800 hours)
  • HID: 2000 – 8000 hours
  • LED: longest life, about 30,000 hours

Likewise, halogen is also the cheapest, at $15 per bulb. Meanwhile, the 9005 HID with 3700 lumens and LED is about $40 and $50, respectively.

You need to keep in mind that if one bulb fails, the other can soon fail too. Besides, the new bulb will usually be brighter than the old one, leading to a slight difference between the two sides. Therefore, you should consider replacing both simultaneously, even if the other is fine, to be on the safe side.

Neither Of The Headlights Work

Rarely do both bulbs fail simultaneously; however, power and grounding problems can cause this. You should check the power supply, fuse, relay, module, and repair as necessary. If the problem does not improve, then replace the light bulb.

High Or Low Beams Do Not Work

Low beams are normal lights used when driving at night or in dimly lit environments. They have a short range and tilt to the ground so that other vehicles can see your car without being blinded.

High beams are long lights with a larger inclination angle than low beams. They are used on roads with almost no light and little oncoming traffic.

When one or both of these lights fail to work, it could be a burn-out, a faulty high-switch, or a loose relay. At that time, you need to check, replace or repair if necessary.

Headlights Works But Dims

The case of dim lights is usually caused by old bulbs, fog lenses, and power sources (Source: Unsplash)

If the dimmed lights always happen, the problem could be with the fog lens or the old bulb. You need to clean the lens or replace a new bulb.

On the contrary, if it only dims under certain circumstances, then the problem lies in the charging system. You can fix it yourself by checking the wiring, accumulator condition, voltage drop, and other system details. Or the auto repair shop can handle them faster and more guaranteed.

What Should I Do If My Headlights Go Out While Driving?

  • The first thing you need to do is retry the dimmer switch, which can be flexible between modes.
  • If that does not work, you should use other lights such as parking, hazard, or turn signals to let other vehicles notice your presence on the road.
  • Then you should find a place to park, check the headlights or call the automobile repair shop if necessary.

How Do I Know If The Headlight Switch Is Bad?

In case you pay a little attention, you will easily recognize the warning signs of a broken headlight switch before it fails. You should also check it before driving, especially when traveling at night. These signs are usually:

Error switching between modes

The basic modes of headlights include low/high beams, fog, parking, and daytime running lights. When the switch fails, only one or certain modes can be controlled, or there is confusion. 

Disturbance of the control mode can cause the lights to go out or limit the light and visibility for the driver. And either way, they can be dangerous to the people in the vehicle.

Error from high beams

This beam is often used when traveling at high speed with no light and no oncoming vehicles. When the light switch is broken, the high beam will be separated and used.

High beams are used in almost no light (Source:

No lights on

A faulty switch will prevent current from reaching the bulbs, rendering them inoperable. It is unsafe if your car does not have headlights, especially on poorly lit roads.

Signs of a faulty switch are often easier to spot than other faults because they involve many parts of the light. If you suspect the switch is faulty, race your vehicle to a professional technician for inspection and repair. 


When your headlights suddenly turn off while driving, you need to stay calm and turn on other lights instead so that other vehicles can recognize your vehicle.

A headlight that goes off is usually a fault of the switch, electrical system, relay, module, or itself. Therefore, you can try one by one to find out the cause and repair or call for help from the garage.

Hopefully, this article has helped you answer the question “Why do my headlights turn off while driving? and calm you down when dealing with this problem.


Bryan Mark is the founder of Bryan’s Garage. He own a small garage in IOWA town, and spend a lot of time on study all technique both hardware and software of car. His mission is contributing the best car knowledge and experience  to the automotive community. It is the most meaningful way to express his passion.

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