Headlight Fuse Keeps Blowing – What Is The Culprit?

The car’s headlight (and probably every other crucial part of the vehicle) are protected with fuses to prevent the electricity from overflowing.

Your driving experience is always smooth and convenient, with accident risks kept at low levels, as a result.

Hence, we trust you can imagine all the disasters that might ensue if the headlight fuse keeps blowing and malfunctioning!

Numerous studies have cited broken light fuses as an (unexpectedly) common cause of road casualties.

So what is happening here, and are there any tips for quick treatment? Bryan’s Garage again enters to discuss all relevant issues and save the day! 

What Are Headlight Fuses? A Quick Overview

Headlight Fuse Keeps Blowing

As you could have already guessed from our informative intro, all electrical systems inside the vehicle (including your headlights) are incorporated with fuses.

They are made to break and “blow” the circuit when too much energy and power surges through them.

That way, all the circuit components will receive proper protection, keeping your car from exploding!

A fuse blowing will likely result in headlights stopping altogether and further unfortunate consequences on the road.

Standard headlight fuses also include relays that switch power between high and low beam headlights.

When the headlight relay keeps blowing, it still allows the energy to flow to high beams. However, the low beam headlight fuse will receive nothing.

Why The Headlight Fuse Keeps Blowing

Want to know why the headlight fuse keeps blowing motorcycle and cars?

Fuses malfunction mostly due to excessive heat (and all the melting that follows). Here are some possible scenarios to consider:

Your Car Has A Short

That might be a bit unlikely since the lights still operate well in normal circumstances; still, you should not rule out the possibility that high-resistance shorts are at play.

Check it by disconnecting all the bulbs first and measuring the gap between the ground and fuse terminal. Any result other than “Infinite” means trouble!

Another signal of high-resistance shorts is the brightness discrepancy. When one bulb shines less than its counterpart, it’s time to fix the problem right away – or at least within a couple weeks.

Do not wait until both headlights keep blowing or the whole electrical system shuts off!

The Bulb Is Too Large for The Light

To our astonishment, this common issue is much more serious than expected.

You may confirm whether it is your case by hooking the meter (at which the short finders are situated). The correct measurement should fluctuate around 5 Amps.

If the number surges up to 10 Amps or even more, troubles have arisen. Internal damage or wrong wattage might be the main culprits here.

The Fuse Terminal Is Failing

Fuse terminals with poor contact could blow and heat the fuse. Observe whether the fuse needs longer periods to spring into action (even 2 or 3 extra seconds matter).

If yes, overheating issues are the case. An environment too hot for the fuses, combined with their own excessive heating, is more than enough to destroy the system.

Signals of poor-contact, blown fuse terminals are not that hard to detect, either. Evidence of fast melting will be littered around the fuse; even novices can see them clearly.

How to Fix It When The Headlight Fuse Keeps Blowing

Detach Its Battery Terminal Connector

Step 1. Pop Its Hood

If you approach the headlights from their back, opening the hood is the first crucial step. Find the huddle’s relay switch, then pull back to release it, popping the hood open.

For those uncertain about the location of the hoods’ safety light, check the vehicle’s manual!

Step 2. Detach Its Battery Terminal Connector

The car’s battery is the energy source for all engine circuits. Hence, you must disconnect the batteries before working on any vehicle’s electrical wiring.

Locate the batteries inside the car’s hood. Next, use a socket wrench to loosen their negative terminals.

Once the nuts have become loose, pull up terminal cables to stick them to the battery’s side. That way, they will not contact the terminal and cause electric accidents!

Cannot locate the negative terminals? Then note that they are indicated with (-) (the minus symbol) or the term “Neg”.

And there’s no need to unplug the positive counterpart. For more info about their wrench sizes, click here.

Step 3. Remove The Plastic Trims

Most modern vehicles use plastic trim to cover the engines and other important components.

So to access your headlights, remove the clips that fasten and hold the trims. Since they are made of plastic (hence easily break and crack), be cautious! 

Step 4. Unplug Pigtail Wires

Check the headlight’s back, and you will see a release clip that binds your light to the hot wire pigtails.

Press down the clamp and keep the pressure there until the clip can be released backwards. After that, disconnect it.

For wires that go straight into the light, do not pull them. Otherwise, you may accidentally disconnect/remove them off the pigtail wires! 

Inspect the pigtail’s internal parts for signals of melting, burning, or damage.

Step 5. Pull And Twist The Light Bulb With Fingers To Remove Them 

Rotate the light and pull it clockwise. The bulb will detach itself from its plastic assembly! 

Step 6. Install New/Replacement Headlights

Now put your newly-bought fuse into the empty slot where old fuses have already been removed. Keep pushing until the device is properly seated.

Do the same with the cover; push in until you hear a firm “clicking” sound, meaning everything has been tightly fitted. Congratulations! 

We suggest you get in the car and drive a few rounds for 5 to 10 minutes to test how it works.

Conclusion

Bryans’s well-researched and inclusive article has discussed and analyzed all possible underlying causes when your headlight fuse keeps blowing.

Fixing your fuse for headlight is pretty straightforward (and affordable) – all the more reasons you should not postpone your visit to the auto parts stores.

Have the car properly checked and diagnosed by professionals right after you detect unusual signals!

And as always, Bryan advises you to follow a monthly maintenance routine to keep the car in peak condition and prevent bad experience in the future.

Do you need more advice, guidance, or clarification regarding headlight fuse blown? Then remember that Bryan’s support box is always open, ready to answer questions from you!

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