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Updated Repair Guide: How to Tell if Headlight Switch Is Bad (+How to Fix)

The easiest way to learn how to tell if headlight switch is bad is to have issues switching between modes. When your headlight is no longer in great shape, you will have difficulty changing the modes.

Still, there’s more to it than just not being able to switch modes.

For instance, your headlight switch might still be working, but you could have a bad fuse, causing your headlights to malfunction. Below, we’ll explore all these options.

How Does a Car Headlight Switch Work?

In most cars, the headlight switch is located on the left side of the steering wheel. On other vehicles, however, the headlight switch or lever is replaced by a knob.

Your headlight switch has a small lever that controls the headlight modes.

For instance, you can turn the lever to the auto mode, which, as the name suggests, turns the headlights on automatically based on how dark the road is.

Other mods will allow drivers to turn on both the interior the corner lights. But the headlights won’t turn on.

And finally, there’s also a mode for the full headlights. Once you’ve selected this setting, all the headlights will remain on until you turn them off.

Reasons Why the Headlights Aren’t Working

Nobody likes spending money on useless parts—so watch out for all these problems and find how to fix your headlights:

1. Headlights Not Providing Proper Illumination

Imagine going down the road at night, and all of a sudden, your headlights top lighting up the road ahead of you.

Now that’s pretty concerning for most drivers—especially if you have trouble driving at night. So, what’s the problem? Well, it could be the headlight door motor.

But hold on, if you have a modern car, that’s not your problem. Due to the rarity of this motor in today’s age, this problem is only found in older vehicles.

That being said, if the headlight door motor quits working, the headlights won’t open, resulting in poor lighting.

Moreover, if this motor is the culprit, you’ve probably noticed that the door opens and closes on and off.

So, before you replace the headlight switch, inspect the motor. If that’s the problem, then you have to get a new one.

2. Headlight Switch Not Working At all

It’s never a good sign when your headlights are not illuminating the road ahead of you.

But it happens from time to time. Still, stay calm. You might be able to fix the headlights by swapping a few fuses.

That said, here’s how you can tell if your fuses need to go:

  • Pop the hood of your car and then find the fuse box. After that, refer to the layout on the fuse box and find the 20-amp fuse.
  • The 20-amp fuse sends power to the headlight switch. If the fuse looks broken on the inside, throw it out and get a new one.
  • Next up, remove the 15-amp fuse. Once again, that one is constantly sending power to the headlight switch. If it got damaged, replace it.
  • Finally, there’s also another 20-amp fuse next to the relay. That fuse also provides power to the switch. Again, change it out if it got damaged.

See? Troubleshooting your headlights is pretty easy. Luckily, swapping out fuses is relatively cheap.

For instance, fuses can go anywhere from $5-$10. That’s pretty cheap compared to replacing relays and bad switches.

Lastly, if you got any questions about your fuses, refer to your owner’s manual or Google to find more about the fuses and relays inside the fuse box.

3. High Beams Stay On

Learning how to check if headlight switch is bad can be as easy as not turning on the headlights on your car.

But sometimes, if you have a faulty headlight switch, the high beams will stay on. This means that the switch on the car is broken, and thus it’s keeping the lights on.

However, if your headlight switch is still in great shape, then there’s still something you can do. That said, here’s how:

  • Disconnect the battery — if the headlights are still on, try disconnecting the battery to turn them off.
  • Pull out the headlight fuse — another short-term solution is removing the fuse that provides power to the headlight switch. Once you’ve removed all the headlight fuses, you’ll shut the lights off.
  • Unplug the headlight relay — if none of that worked, disconnect the headlight relay, and the lights will turn off.

Those are simple fixes you can try at home, but keep in mind that you still need to diagnose the car to know what’s going on behind the scenes.

4. Headlights Are Not Bright Enough

As we noted before, driving in the dark is no fun if your headlights are not doing their job.

One can only think about those times you weren’t driving at night. So, what is exactly going on here? Well, let’s do a little bit of troubleshooting.

  • Wrong size bulbs — if you recently installed new headlights, you probably got the wrong size. As a result, your bulbs are not outputting enough power.
  • Heavily oxidized headlights — if the lenses of your headlights got oxidized, you have to clean them, and your headlights should light up the road again.
  • Not enough voltage — If you got the right headlights, then you might want to check the circuit and find out if there’s enough voltage.

Yeah, that’s a lot of work, but it’ll save you some money if you take enough time to go through those three steps. That said, if you want to restore your headlights, watch this well-made video:

5. Only One Headlight is Working

Bad headlight switch symptoms are pretty easy to diagnose.

But you might be surprised to find out that the headlight switch is still working and that the problem is something unrelated.

For example, you could have a damaged bulb. Bulbs don’t go out all the time.

In fact, you should replace your headlights after nearly 90,000 miles, meaning you got plenty of time before they burn out.

But if you went over the interval, then it might be to replace the bulbs. Even if it’s just the right bulb, it would be better two replace both sides simultaneously for better results.

And finally, check the fuses. Some vehicles have a single fuse for both headlights. Above, we quickly went over this.

But if your vehicle only has a single fuse to run the headlights, both bulbs wouldn’t work if the fuse got damaged. However, some cars can have up to 4 fuses.

Why is that? Well, some vehicles might need those four fuses for the right and left sides. If one of those fuses stops working, then only the high or low beam will work on one side.

Not sure if you got that many fuses? Follow these simple steps:

  • Open the fuse box on your car and then find the diagram on the box. There’s a lot of information on that layout, but you only care about the fuses for the headlight.
  • Find the one that says “HEAD HIGH LH.” That’s the fuse for the left side. The one for the right side should say “HEAD HIGH RH.”
  • For the low beams, find the ones that say “HEAD LD LH” and “HEAD LD RH.”

In this case, we got four fuses, but you might have fewer depending on your vehicle.

Once you’ve figured out how many fuses you have, pull them out and make sure they’re not burned inside. If they look damaged or split, replace them.

6. Can’t Switch Between Headlights

One of the most common symptoms of bad headlight switch is issues switching the headlights. That always gives it away.

But in some cases, drivers might be able to switch between modes but only on certain occasions. That’s a clear sign you have a faulty headlight switch.

Headlight switches wear out over time. This happens to the best of us, so don’t worry too much about it.

Replacing a switch is easy and cheap. You don’t need to go to the local dealer and have them work on your car.

Save yourself some money and pick up a new one for $30. Want to learn more about this? Then here’s a short but helpful video to replace your headlight switch:

7. Automatic Headlights Are Not Working Anymore

As you’ve seen by now, headlights can work in strange ways, and it’s pretty hard to track down the problem with so many types of headlights systems.

But there’s still one problem we haven’t talked about.

And it’s the fact that your vehicle could have a sensor that automatically turns on the headlights when it can’t sense any nearby light.

Unfortunately, these sensors can fail at any point and time. And when that happens, your high beams will quit working. So, you’ll have to turn them on manually.

Alternatively, check that the bulbs are still working. Even if you replace the sensor, it won’t do anything if your bulbs are not outputting any power.

8. Bad Relay

So far, we’ve covered different methods on how to tell if headlight switch is bad.

But if the information above didn’t solve your problem, it might be time to get a new relay.

In that case, you want to check the relay before getting a new one. So, here’s how to do it:

  • First and foremost, open the fuse box. Now, you should see several relays, and if you take a closer look, you might notice that some of them have the same number, meaning they are interchangeable.
  • So, take the headlight relay out and then swap it with the same model. If your problem goes away after switching the relays, it’s safe to assume that the headlight relay was in bad shape and must be replaced.

New relays are somewhat expensive and can cost nearly $80, although this price is worth the money, considering your headlights will keep you safe at night.

Frequently Asked Questions

With the correct information and advice, you can fix your headlight switch. That said, here’s some info about headlights to help you fix them:

How much does it cost to replace a headlight switch?

Replacing a headlight switch is not as difficult as you might think. But if you choose to pay for this job, expect to be quoted about $150 for the labor.

What would cause my headlights to stop working?

Apart from the usual reasons why your headlights might not be working—like bad bulbs and fuses, check the headlight switch. If you have trouble switching modes and the headlights don’t turn on at all, it could be the switch.

Is there a fuse for headlights?

Yes, but depending on your vehicle, you might have several fuses for the headlights. To find more about this, head over to the fuse box and see the diagram showcasing all the fuses.

Why do my high beams work but not my headlights?

You’ve got two possible culprits here. First, you could have a faulty bulb, which is almost always the case.

But if that doesn’t work out, then inspect the fuses. Your vehicle might have several fuses for both sides, and if one stopped working, the left or right side wouldn’t work.

Conclusion

So, did you figure out how to tell if headlight switch is bad? Remember, a faulty headlight switch feels pretty weak and won’t let drivers switch modes. And on some occasions, the lights won’t work.

But before throwing random parts at the vehicle, get the easy stuff out of the way.

For example, make sure to inspect the fuses. Blown fuses can make your headlights malfunction since they provide power to the headlight switch. So, watch out for that.

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