The Ultimate troubleshooting Guide To Aux lights,

The Ultimate troubleshooting Guide To Aux lights

Lights are an essential part of any vehicle. It’s not just a useful aid to see where you are going, lights on your vehicle allow others to register your presence. Of course, lights also include brakes and indicators which are exceptionally important for telling other road users what you are doing.

What Are Aux Lights?

On every vehicle there must be certain lights, these are the sidelights, headlights, rear lights, brake lights, etc. You need to comply with the law and have the right lights capable of being used at all times. But, you can also legally add auxiliary lights. These are sometimes referred to as daylights.

In some vehicles daylights are fitted as standard, in others, you can add them. In most trucks, you’ll find aux lights on the front, sides, and rear. They help other road users to see the truck coming. As trucks are large and heavy, it’s easier for other road users to take evasive action. In this sense the aux lights don’t just look good, they perform a valuable safety aid.

Of course, like any part of a vehicle, there will be times when they go wrong. Fortunately, you have this guide and the assistance of a good automotive electrician to get you back on the road.


The most obvious starting point when your aux lights aren’t working is to check the light itself. Due to their position on the vehicle they may feel the wrath of the road more often than other lights. In short, the lens and the bulb may have been smashed by road debris.

If the lens is still intact you’ll want to check the bulb, they don’t last forever. Carrying a spare you know works will allow you to swap the bulbs and check if this is the issue.

Fuse Blown

The next step is to check your fuse panel. It should be noted that fuses usually control several lights. If the aux lights are original equipment they are likely to share a fuse. In other words, if the other lights are working it’s probably not the fuse.

But, if the lights are an aftermarket fit they will have an inline fuse that needs to be checked and replaced if necessary.

Onboard Computer Issue

When your aux lights are standard the electrics will go through the onboard computer, along with everything else in the vehicle. This means it is possible that the onboard computer is causing your lights to misbehave.

The easiest way to verify this is to get your automotive technician to plug in a diagnostic machine and read the error codes. This can be an expensive fix.

Wiring Problem

Finally, it is important to check the wiring to your aux lights. It may be exposed to the elements and could have been damaged. There are plenty of ways this can happen!

Damaged wiring will stop the aux lights from working and you’ll need to replace the wiring section before you can get them working again.

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