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Although headlight technology isn’t very complicated, there are several ways for them to fail. Therefore, if your headlights suddenly cease working, it’s critical to identify the malfunction you’re dealing with and proceed accordingly. So important for you to at least know what to do when your car headlights fail.

The kind of failure you’re dealing with will determine your chosen troubleshooting procedure.

With that in mind, it’s a good idea to check if both or simply one of your headlights has failed and whether the low or high beam setting is still functional.

How Do Headlights Function?

The good news is that headlights are straightforward compared to other automotive systems. A fuse, relay, bulb, and switch are all used in most headlight systems. 

Adaptive headlights or running lights may be available depending on the age of your vehicle. Nonetheless, even these more advanced lighting systems operate in the same way.

When the headlights are turned on, a relay in the system is activated. This relay provides the link between your car’s battery and your headlights.

Fuse boxes are also included to protect the remainder of your electrical system from a power outage. If you want to use your high beam lights, you’ll need specific relays.

You may notice that your headlights no longer turn on if one of these components (or several of them) stops working correctly.

Is This a Do-It-Yourself Procedure?

If your headlights quit working, you may be able to repair them yourself in some instances. You may be able to change the bulb yourself using modest equipment, especially if the problem is a burned-out headlight.

If the situation is more complicated, you might want to take it to a mechanic with more specialized electrical equipment.

For example, while you may not have a voltmeter at home, your technician most likely does.

To make your work easier, you can join a 5-hour class online to learn more about the possible hazards on the road.

Fixing a Faulty Headlight

When one headlight quits working while the other continues to function normally, the issue is likely a burned-out bulb.

Although your headlight bulbs could be subjected to identical circumstances, they are unlikely to fail simultaneously. As a result, it’s rather usual for one bulb to burn out before the other.

Before declaring your headlight bulb defective, inspect the electrical connector for evidence of damage or corrosion. If the connector has become loose, reattaching it may solve the problem.

However, you’ll need to go a little deeper to discover why it became loose in the first place. Another thing to consider before replacing a burned-out headlight capsule is whether there were any external explanations for the failure.

What Should You Do If Both Headlights Fail?

The bulbs aren’t normally at blame when both headlights cease working simultaneously. The biggest exception is when one headlight fails first, goes unnoticed for a while, and then the other headlight fails as well.

If you have a voltmeter and feel the bulbs are faulty, you should start the troubleshooting process by checking for power in the headlights.

Turn on the headlight switch, connect the negative lead of your meter to a known good ground, and afterward connect the positive lead to each headlamp connection point.

If the problem is burned-out bulbs, one of the terminals should indicate battery voltage, and the other two should show nothing.

After that, you may try to turn on your high beams. That should lead to a new terminal indicating battery voltage. If that’s the case, changing the bulbs should resolve the issue.

How to Repair Faulty Low or High Beam Headlights

Many of the same issues that cause headlights to cease operating completely might also cause low or high beams to fail.

If only one bulb turns off when the high beams are turned on, but the other works well, the high beam filament in the first bulb is probably burned out.

It is also true if one bulb used to function on high beams but now only works on low beams.

The failure of high or low beams is almost often caused by a relay or switch fault, and the troubleshooting process is identical to the one described above.

The high beam, dimmer, or passing switch might or might not get integrated into the headlight switch, and some cars have a separate relay only for the high beams.

Final Thoughts

Your headlight will fail if any of the required elements cease operating correctly. You can typically backtrack to find the ideal spot to start troubleshooting by looking at how they failed.

When headlights quit operating, it’s either an electrical or physical problem with the bulbs.

The most critical tip is to keep track of the kind of failure you’ve had for you to get to the solution of the problem as early as possible.

However, to avoid headlight failures, you can check out the things you need to do while driving at night.