Troubleshooting LED Fog Lights

led car fog lights on front bumper

There’s no doubt that LED fog lights can be very useful on a car. When switched on they can cut through the mist very effectively. However, like all lights, LED fog lights can develop problems. Knowing how to resolve these problems can save you a great deal of money. Most simple problems can be discovered and remedied quite cheaply without having to resort to an expensive auto electrician.


The first thing to check if the LED fog lights don’t work is the fuse box. Look in your owner’s manual. Not only will this give you the location of your fuse box, but also which fuse controls which circuit.

Use a plastic fuse puller to remove the fuse. Look at it closely to see if the wire is intact. If not, replace the fuse with a new one that’s exactly the same size. Be sure it’s seated properly. Try the fog lights again to see if they work. Be aware that on some models the fuses can be under the hood, not in the passenger compartment.

Bulbs Out

If the bulbs are out you can test to see if the problem is in the bulb or the wiring quite simply. Use an LED voltage tester (available from all hardware stores) to determine whether the voltage is going through to the bulb.

Strip off a little of the wire insulation by the wiring harness. Turn on the fog lights, then touch the two wires using the tester probes. If the bulb on the tester lights up, then the fault is with the LED fog light bulbs and they’ll need to be replaced. Replace them according to the manufacturer’s instructions.

No Power

If there seems to be now power going to the LED fog lights you can check to discover the source of the problem. Again, it needs the LED voltage tester. Keep the fog lights on for this.

Touch one wire of the tester to one of the wires, either positive or ground, going to the LED fog lights. You’ll need to strip off a small piece of insulation for this. Take the other wires from the tester and touch them against the two terminals on the battery. If there is power then the light on the tester should glow.

Repeat the process with the other wire going to the LED fog lights. If the light doesn’t glow on one of the wires you know that the problem lies there. At this point, unless you’re well-versed in auto electrics, you might want to take the vehicle to a professional. At least it will cost less, having pinpointed the problem.

Proper Bulbs

Be sure that you’ve replaced the LED fog lights with the correct bulbs. Failure to do so can lead to the fog lights not working properly or not at all. Taking the time to be certain you buy the proper bulbs can save you many problems and time troubleshooting problems. If you’re not sure which bulbs are correct, ask at the auto parts store.