HomeTips & GuidesHeadlight Relay Switch: Everything You Need to Know

Headlight Relay Switch: Everything You Need to Know

If your headlight develops problems, your first instinct is to replace it. The problem is that sometimes the headlight lamp may be fine. In this case, the culprit is the headlight relay switch.

This article will help you learn about the headlight relay switch. We will find out what it is, how it works, and how it looks. We will also look at the symptoms of bad headlight relay.

Table of Contents

What is the Role of Headlight-Relay?

The headlight relay plays two key important roles. 

The first one is current capacity control. The headlights require high current capacity. 

The second role is to protect the headlight circuit. High-current circuits are always at risk of overload. 

Image of a Headlight lamp

(Image of a Headlight lamp)

Location of the Headlight Relay

The headlight relay switch is normally found in the engine compartment. It can be found under your dashboard in some car makes. You can look at your car manual to find the exact location of the relay switch.

Headlight Relay Fuse

( Headlight Relay Fuse)

Causes and Signs of a Bad Headlight Relay

A bad relay can be due to water damage. The other cause is wear and tear. When the relay switch gets into contact with water, it leads to corrosion. This corrosion can affect the effective functioning of your relay. To deal with this problem, check out the following signs. 

No Low or High Beams

If your car’s relay is damaged, the lights will fail to switch between low and high. In most instances, you will only get one option.

Driving during night hours can be problematic if you only get a low beam. You can simply solve this problem by replacing the relay fuse.

(Headlight replacement switch)

Intermittent Headlights

Many issues can result in intermittent functioning in headlights. The main causes are relay-blown fuse and wiring issues. Replace the blown fuse or the entire relay switch to solve the problem.

Headlights Won’t Turn Off

Another factor that shows a broken relay switch is permanent headlight lighting. The headlight may go on and fail to switch off even after turning the switch off.

You can solve this problem by temporarily turning the lights off. Locate the relay switch and disconnect it to stop the light.

Random Pop-Up Headlights

The constant irregular pop-up is a common indication of a broken relay switch. The pop-up lights may go on/off in unprecedented situations. This should be a red flag.

How to Replace the Bad Relay?

It is very easy to replace a bad relay. Locate your relay and pull it out gently. It would be best to be careful not to damage the fuse or box during removal. Below are steps to follow to replace a relay.

Step #1 Find Relay Closure

The first step should be to locate the relay_closure. The relay closure connects the main power source with the relay. Use your manufacturer’s manual and find the pinpoint location of the relay for your current car model.

Step #2 Remove the Lid

Take off the fusebox lid to access the internal components of the fuse box. Locate the relay fuse for your headlights as indicated in your manual.

You should ensure that the lid is not broken during removal. Breaking it can cause trouble later when you need to lock it.

Step #3 Toggle Out the Old Relay

Remove the old relay by pulling it out. Toggle the fuse as you pull it out until it gets out of position. To avoid breakage, use gentle side-to-side movements.

Step #4 Replace Old RelayWwith New One

After removing the old relay, place the new one in the same position. To insert the relay, carefully place the relay switch in position so it does not get damaged.

You do not need to replace the entire headlight relay switch. Replacing your relay fuse only is enough. All relay switch replacement parts are readily available online.

Start your vehicle and try the headlights to see if they work. Cover up your fuse box and return to your dashboard.

Headlight replacement procedure

(Headlight replacement procedure)

Cost for Replacing Headlight Relay

Most switches range between $20 and $25. You can then replace the relay at home using DIY steps.

Automobile relay

(Automobile relay)


If you are experiencing issues such as intermittent lighting, you must replace your relay switch.

Find a good relay switch replacement online. After securing the right switch for your car model, replace it according to the highlighted steps in this post. 

Hi I am Christa, sales manager of Cloom.

I have extensive expertise and experience in wiring harnesses and I believe I can help you.

And we have a very professional technical team who can clearly understand the customer’s needs and give professional suggestions and solutions after receiving the drawings.

If you also have wiring harness needs, please send me the drawing so that we can give you our quote and start our business.

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