Skip to content

How to Wire a Light Bar in 4 Easy Steps

Light bar on vehicle

Learning how to wire a light bar onto your truck or SUV will help you enjoy safer nighttime driving and brighten up your off-roading adventures after the sun goes down. With their lower power requirements and more compact sizes, modern LED light bars are easier to install than older halogen light designs. To easily wire a light bar at home, follow these four basic steps.

1. Use a Relay Over a Simple Switch

Even with the lower power draw of an LED, it’s still a better idea to use a relay instead of running full current through a simple switch. Relays are usually rated to handle a much higher load than switches, which means they won’t overheat or potentially fail while being used. They also typically offer a lower voltage drop and can be combined with a single control switch that will allow you to turn a number of lights on and off at the same time, making for cleaner installation.

2. Choose a Fuse

Truck with light bar

Putting a fuse between your relay and the battery will also protect your vehicle’s electrical system in case anything unexpected happens while your lights are on. A fuse is cheap, and it will sacrifice itself before any power surges make their way to your lights or spread through the rest of your truck’s wiring. Make sure you choose a fuse that offers the correct amp rating for your lights’ power draw — if it’s rated too high, it won’t trip when needed.

3. Make Sure Your Grounds Are Good

You’ll most likely be wiring your LED light bar relay’s power lead directly to the battery, but you won’t necessarily use the same battery’s negative terminal as your ground. You can ground your wiring to the vehicle’s chassis, as long as it offers a clean connection between your circuit and bare metal. You’ll want to test that ground with a simple multimeter before making it permanent to ensure a strong contact.

4. Decide on an Auxiliary Switch or Factory

One more important aspect of how to wire a light bar is the kind of switch you use. You can wire an aftermarket switch inside the vehicle that will trigger your relay. For a cleaner installation, you can also tap into the wiring harness for your vehicle’s high-beam headlights, and send power to the relay once those are activated. This is helpful for two reasons: If the high beams are on, it’s dark enough to require your light bar, and on a modern vehicle, this will prevent you from accidentally leaving your LEDs on with the vehicle’s ignition and lighting turned off, saving your battery from being drained.

By following these steps, you’ll transform the safety and enjoyability of your nighttime explorations, no matter how far they might take you from civilization’s glow.

Check out all the lighting products available on NAPA Online or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on light bars, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.

Photo courtesy of Creative Commons.

Benjamin Hunting View All

Having been bitten by the car bug at a young age, I spent my formative years surrounded by Studebakers at car shows across Quebec and the northeastern United States. Over ten years of racing, restoring, and obsessing over automobiles lead me to balance science writing and automotive journalism full time.  I currently contribute as an editor to several online and print automotive publications, and I also write and consult for the pharmaceutical and medical device industry.

Leave a Reply

Your email address will not be published. Required fields are marked *