An LED light bar is one of the most popular truck upgrades, and it is a job most owners can do in an afternoon. This guide covers how to pick the right bar, where to mount it, and how to wire it safely with a relay, fuse and switch.
1. Pick the right beam pattern
- Spot – a narrow, long-reaching beam for seeing far down the trail or road.
- Flood – a wide, shorter beam that lights up the area around the truck. Great for work sites and camp.
- Driving / Combo – a mix of spot and flood in one bar. The best all-around choice if you only buy one light.
Bar length should match the mounting spot: 10–20 inch bars fit bumpers and grilles, 30–50 inch bars fit roof racks, windshield mounts and full-width bumpers. Shop the full lineup in LED Light Bars or go smaller with cube and pod lights.
For a bumper or grille, a 20-inch bar like the Baja Designs OnX6+ 20-Inch Straight LED Light Bar, Driving/Combo Beam is a common fit.
For a roof rack or full-width bumper, step up to a 40-inch bar such as the Baja Designs OnX6+ 454003 40-Inch Straight LED Light Bar.
2. Choose a mounting location
- Bumper or grille – easiest install, short wire run, and less wind noise.
- Roof or windshield – the most reach, but more wind noise and glare off the hood. Use vehicle-specific brackets so you don't drill the roof.
- Rear / chase lights – great as backup and work lights.
Use the brackets made for your bar or vehicle from Light Mounts & Brackets, and torque the hardware to the manufacturer's spec. Loose mounts vibrate and wear out connectors.
Worried about theft? The Baja Designs 660302 Anti-Theft Security Hardware Kit is made for OnX6+, S8, XL and LP series lights.
3. What you need to wire it
- A wiring harness with an inline fuse and relay (most bars include one – if not, see Light Wiring Kits & Switches)
- A switch you can reach from the driver's seat
- Wire loom, zip ties and a rubber grommet for the firewall
- Basic tools: socket set, wire cutters/strippers, crimper, multimeter
If your truck has factory upfitter switches, a harness like the Baja Designs OnX6/S8/XL Upfitter Wiring Harness 640094 is designed to connect to them. Check the listing for compatibility.
4. Step-by-step install
- Disconnect the negative battery cable before you touch any wiring.
- Mount the bar and aim it roughly level. You'll fine-tune the aim at night.
- Route the harness from the bar to the battery, keeping it away from the exhaust, belts, fans and sharp edges. Loom it and zip-tie it every 12 inches or so.
- Mount the relay in a dry spot under the hood, close to the battery.
- Pass the switch lead through the firewall using an existing grommet when possible. If you drill a new hole, seal it with a grommet.
- Mount the switch in the dash or a switch panel and connect it.
- Connect power last – the fused positive lead to battery positive, ground to battery negative or a clean chassis ground.
- Reconnect the battery and test. Check that the bar turns off with the switch and that nothing gets warm.
5. Aim it and stay legal
Aim the bar at night against a wall or down an empty road so the hot spot sits slightly below the horizon. Most states only allow auxiliary off-road lights to be used off-road, and many require them to be covered on public roads. Check your state's rules and add a light cover if needed.
Common mistakes to avoid
- Skipping the relay and running the full load through a small switch
- No fuse, or a fuse that's too big for the wire
- Wires resting on the exhaust or against sharp metal
- Pointing a roof bar straight out, which blinds other drivers and causes glare off the hood
Not sure what fits your truck? Select your vehicle at the top of any page, use our Live Chat parts finder, or call us at (919) 283-6645. We're happy to help you pick the right bar, brackets and harness.
Always follow the instructions included with your light. If you're not comfortable with 12-volt wiring, have a professional installer do the job.