Proper way to wire a LED bar

Got a call today that my truck arrived at the dealer and I'll be picking it up tomorrow (2016 2500 4x4 6.7 cummins tradesman crew). One of the first mods I want to do is adding a LED bar to the bumper. I want to route a switch to the dash so its only on when I need it. My question is what is the best way to wire that up? Now a days, with all the electronics on a truck, I don't want to tap into the wrong circuit and fry the computer or something so advice from those that have done this (installed and wired up a LED bar, not fried their computer) would be appreciated.

Thanks in advance!

Buy a light bar wiring harness.

AustinB said:

Buy a light bar wiring harness.

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I agree. Just be sure to fuse the positive wire you connect to the battery.

X3 on the wiring harness. The light bar you buy will most likely come with one.


Won't fry any electronics or effect any systems on your truck. Runs right off the battery.

Yep, that's basically what my harness looks like. Basically two connections, one to the positive terminal of a battery and a ground.

You don't really need the relay.
Just connect I would say about a 20 amp fuse right at the battery using 14 awg wire that then runs to a switch thst is rated to a high enough amperage and then to the lights. Ground the lights at the nearest point on the frame.
Done!

Sent from my SAMSUNG-SM-G900A using Tapatalk

HemiPower36 said:

X3 on the wiring harness. The light bar you buy will most likely come with one.


Won't fry any electronics or effect any systems on your truck. Runs right off the battery.

Click to expand...

Ok, thanks. I think I'm understanding this wiring diagram except for one thing. It shows power (+) going to the switch (right next to where it says "ground to frame or battery"). Where is that power coming from? Is that from the battery also?

I always use a relay..... it's cheap insurance.

I have mine wired directly as the diagram.... I can turn it on whenever I need it.

The heavier gauge wire is always best along with the heavy duty fuse holder.

Do it right, do it once!

Cummins Dog said:

Ok, thanks. I think I'm understanding this wiring diagram except for one thing. It shows power (+) going to the switch (right next to where it says "ground to frame or battery"). Where is that power coming from? Is that from the battery also?

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Usually from a switched 12v source, inside the cab. That would restrict using the light, only when key is on/acc.

Or pull from always hot, and use it anytime.

I ran mine off a SPDT switch. That way I could have it on when the truck is off, on with my high beams, or off completely.

Cummins Dog said:

Ok, thanks. I think I'm understanding this wiring diagram except for one thing. It shows power (+) going to the switch (right next to where it says "ground to frame or battery"). Where is that power coming from? Is that from the battery also?

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The way it works is:

Red goes to (+) battery. Black can either go to (-) or grounded elsewhere (A screw or bolt somewhere on the frame). Mount the relay (the square box thing) close the battery. Plug the connector to the light. Route the switch into the cab. All the power to run your light comes off the battery.

I have used multiple harnesses (rigid, KC, VisionX). KC loves to have other wires going on (green, white, brown, yellow, etc.). Took me a second but it got it figured out. I like the rigid industries harness. Super simple just like the one I pictured above.

Once you get your setup, revisit this thread, post your harness photos and we can help you get it installed. No problem. Tons of videos on YouTube that helped walk me through the process too.

I use the same wiring harness too and makes it very easy.

Also to bring the wiring in the cab use the clutch cover plate. Makes it look like factory.

HemiPower36 said:

The way it works is:

Red goes to (+) battery. Black can either go to (-) or grounded elsewhere (A screw or bolt somewhere on the frame). Mount the relay (the square box thing) close the battery. Plug the connector to the light. Route the switch into the cab. All the power to run your light comes off the battery.

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True, but this can be confusing for someone that doesn't understand how a relay works (I've been there).

The lights do in fact get their power from the battery.. but the question is why there is an extra + wire off the switch.

The switch powers the relay, which then sends the power (from the battery) to the light.