Bad Fog Light Relay Symptoms

Fog lights are indispensable for driving safely through inclement weather conditions like fog, heavy rainfall, or snow. The fog light relay plays a crucial role in activating and deactivating the fog lamps on command.

To begin with, a relay is an electronic switch that has a primary and secondary side. The primary side is the electromagnetic coil that triggers the secondary contacts to close. The secondary contacts deliver power to the load. That way, a small switch can be used to activate a heavy electrical load rather than the switch having to be robust enough to carry the load on its own.

A relay is an electronic switch that has a primary and secondary side. The primary side is the electromagnetic coil that triggers the secondary contacts to close. The secondary contacts deliver power to the load.

– Richard McCuistian, ASE Certified Master Automobile Technician

Pro Tips are nuggets of information direct from ASE-certified automobile technicians working with CarParts.com, which may include unique, personal insights based on their years of experience working in the automotive industry. These can help you make more informed decisions about your car.

Pro Tip: Relays are used for other reasons as well. In the case of fog lights, they’re only supposed to be active when the headlamps are on “dim,” which is by law. And fog lights must always be mounted below the bumper, not above it.

The fog light relay lets you activate and deactivate the powerful lamps as needed. If the relay develops an issue, it can interfere with the fog lights, potentially depriving you of the extra illumination you need when driving in severe weather. Read on about the symptoms of a faulty fog light relay.

What Is the Fog Light Relay?

The fog light relay is an electrical relay that regulates the current flow to the fog lights. It connects to the headlight switch. When you switch on the headlights, the fog lights illuminate as well.

You can usually find the fog light relay in the engine bay within easy reach of the battery. Look for a fuse box under the hood.

Symptoms of a Bad Fog Light Relay

Like any other automotive part, the fog light relay accumulates wear and tear over time. The worn-out relay’s components degrade with use, becoming less efficient or failing outright.

While a faulty fog light relay won’t disable your vehicle, it will make driving during bad weather more difficult. Fortunately, the relay will show signs that indicate it needs replacement.

Here are the most common symptoms of a faulty fog light relay:

Fog Light Relay Makes Loud Clicking Sounds

Do you hear a sharp click when you switch on the fog lights? That strange noise is one of the earliest warning signs of a fog light relay issue that might require the electrical part’s replacement.

Most fog light relays issue a clicking sound when you switch the fog lights on. The sound comes from the relay’s internal components closing the electrical circuit to enable the current flow to the fog lights.

You can barely hear these clicks from the passenger compartment. When these sounds grow louder, there’s usually an issue with one or more of the fog light relay’s internal components.

Fog Lights Don’t Switch On

Clicking noises are worrisome, but at least the fog lights will still turn on most of the time. But if you ignore the audible symptom of a faulty fog light relay, you might reach the point where the lights don’t illuminate. Sometimes, this can happen without the advanced warning of loud clicks from the faulty relay.

The headlight switch serves as the control button for both headlights and fog lights. However, it’s the fog light relay that controls the lamps’ power supply. The current must pass through the relay to reach the fog lights.

A faulty fog light relay can’t send electricity to the fog lights. Without a steady supply of power, the fog lamps won’t illuminate. In the worst case scenario, the relay can fail while you’re driving in bad weather.

Fog Lights Stay Illuminated

Switching off the headlights should also turn off the fog lights. You know there’s an issue when the fog lamps continue to run. But does the problem lie with the fog lights or another part like the fog light relay?

The fog light relay cuts the current flow to the fog lights once you switch off the headlights. As the relay ages, its fog light relay wiring can develop issues like internal shorts that fuse part of the circuit in the closed position.

More About the Fog Light Relay

Not all vehicles come with fog lights as standard equipment. Sometimes, you must get them separately and install them yourself or hire a mechanic to do the job for you.

In these cases, some drivers wire the fog lights to the battery. While this approach keeps things simple, it causes issues that can lead to discharged batteries and burned-out fog light bulbs.

Instead, you should install a fog light relay as the intermediary between the fog lights and the battery. The relay will help extend the lifespan of your vehicle’s battery and fog lights.

What Does the Fog Light Relay Do?

By closing the electrical circuit, the fog light relay enables current flow, providing the lamps with the electricity they need for operation. The relay can also do the opposite, cutting off the power supply to turn off the lights.

The fog light relay gives several benefits to your vehicle. First, it lets you use a low-voltage light switch to control the fog lights. Instead of buying a separate switch capable of handling high voltages, you can wire the relay to your vehicle’s headlight switch.

Second, wiring fog lights with a relay contributes to battery power conservation. Most fog light bulbs consume more electricity than dimmer bulbs.

Connecting the fog lights directly to the battery will keep the lamps on until you turn the switch off. This can drain your battery, especially if you forget to turn off your fog lights. If the alternator can’t provide enough charge, the battery can die.

In contrast, a fog light relay requires activation before it sends battery current to the fog lights. It will prevent battery drain when you aren’t running the fog lights.

Last but not least, wiring fog lights with a relay helps extend the fog lights’ service life.

Directly wired fog lights receive the full force of the battery’s electrical current. The constant current flow can increase the fog light bulbs’ temperature until the parts burn out.

Installing a fog light relay ensures that the electrical current only flows to the lamps when you want it.

How Much Does a Replacement Fog Light Cost?

When a fog light relay goes bad, you might also find yourself in the market for new fog lights. A replacement fog light can set you back anywhere between $10 and $1,100. Depending on factors like the product’s brand, the price tag can vary between products.

Where to Get Car Fog Lights for Your Vehicle

There’s nothing more dangerous than driving in low visibility without any means to see your surroundings. The risk of hitting pedestrians, items, and other vehicles is high. If your fog lights are faulty, don’t put off replacing them. For top-notch replacements that are built to last, consider shopping online at CarParts.com.

All our fog lights passed the highest quality control standards from industry professionals. We source them from leading aftermarket brands to give you only the best options for your ride.

To get started, fill out our vehicle selector to view compatible parts. Then, funnel the catalog results according to your preferences using the search filters. You can place your order using our website, or you can also dial our toll-free hotline for further assistance.

If you’re on a budget, don’t worry. Our competitive pricing ensures that you’ll get the parts you need without sacrificing quality or breaking the bank. We also have strategically located distribution centers across the US, so you won’t have to wait long to get your new fog lights.

Drive confidently in low-visibility conditions. Check out our catalog and shop for new fog lights today.