Whether you’re adding front fog lights to a vehicle that has them already, or installing them for the first time in a car that doesn’t have them, figuring out how to wire them is an important part of the process. There are a few things to keep in mind when wiring your new lights, including how they’re supposed to mount, the size and shape of the wires, and where you’ll plug the switch and relay into your car’s electrical system.
Fog lights are intended to illuminate the road in heavy fog, snow and other poor visibility conditions. They’re different from daytime running lights, which are designed to light the road while driving in normal weather and daylight.
They’re typically mounted low on the vehicle, below the headlights and above the road surface. This allows them to illuminate the road without casting direct light into the fog itself. It also helps you see the white “fog line” that outlines the road surface in fog.
Before wiring any wires, draw a diagram on plain paper. Label each component in the diagram to help you keep track of everything you’re working with. It’s also helpful to refer to the factory workshop manual (reprints are available from Moss) for reference.
Next, you’ll need a pair of fuses to power the relay that will turn on the lights. You’ll need a fuse for each fog light bulb, so make sure you have plenty of extras on hand. A 10-amp fuse works best for most bulbs.
After you have all of your wires in place, it’s a good idea to test everything out to ensure that the fog lights work properly. This may require you to re-aim them from time to time, as the constant vibration of your vehicle can shift their alignment from time to time.
Depending on your vehicle, there are several different styles of fog lights that you can choose from. Most come in a round or rectangular shape and fit in specially-designed holes, often under the headlights. Other styles include grille and rack mounts that fit above the vehicle or onto a front brush guard.
If you have a grille or rack mount style, you’ll need to cut out a spot for the fog lights. There’s usually enough space under the bumper, though you may have to remove a fender liner in some cases.
Once you’ve got the lights cut out and a spot prepared, it’s time to wire them up. You’ll need a switch that will turn on the fog lights when the low beam headlights are on. You’ll also need a relay that will control the switch and turn on the fog lights when the headlights are turned off.
Getting your fog lights wired up can be a relatively easy process, as long as you’re familiar with the basics of your vehicle’s electrical system. If you have any questions about this process or any other part of your vehicle’s wiring, be sure to consult with a NAPA Auto Parts expert for guidance.