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A common question we get is, "What is the relay for and how do I wire it to my light bar?" To provide more color to this, we will cover:
- What is a relay
- Why you likely need a relay
- How to connect your relay
What is a Relay?
A relay is an electrical switch that controls the power to your led light bar. It allows a low current "switch" circuit to control the electricity flow of the high-current circuit load, like your LED Light bar for example.
Why do I need a Relay?
When you create a circuit, a loop of electricity from the battery positive to your LED Light bar to your battery negative, if you just put a switch between the battery and the light, the switch has to be rated for the full current (amp draw) of the light. Our lowest amp draw LED light pods draws about 1.4 amps. While many switches will be able to handle that, for example, the Extreme LED Rocker Switches are rated for 20 amps at 12v. There are very few switches that are designed to handle the the draw of one of our larger light bars like the Extreme LED X2 52" dual row lightbar, which draws about 40 amps. If you are running too many amps through a component not rated to handle it, bad things can happen like overheating/melting the switch, melting the wires, or at a minimum reducing the current that is getting to your lights which will reduce the power output.
Another reason you may want to add a relay is to utilize electrical currents from existing "switches" in your vehicle. Let's say you want to have your LED Light Bar come on with your high beams, or reverse lights, for example. Read more about that below.
To see additional light bar options, checkout our full line of lightbars
How to wire your LED Light Bar using a Relay
The relay will have 4 prongs on it, marked 30, 87, 85, and 86. Kind of cryptic isn't it? Well if you are just going to use our wiring harness, and a switch, you don't need to know what any of this is, because it comes pre-wired and plugged in together. In fact, our lights also have plug and play connectors so the only electrical wiring you need to do will be connecting the harness to your battery.
However, if you are looking to use an electrical current from another "switch" in your vehicle such as your brakes, reverse lights or turn signals to activate your LED lightbar, then you'll need to do a bit of rework. We will refer to these existing functions in your vehicle as a switch, to clarify that these on/off functions that already exist in your vehicle can be used the same as a switch.
First, an explanation of what the 30, 85, 86, and 87 numbers are in the picture:
- 30 and 87 create the switch to your LED lights. By default this switch is open, so current cannot get from the battery to your lights.
- 30 is your power source for your LED lightbar. It connects to the positive (+) side of your battery or to a switched power source that only gets power when your ignition is on.
- 87 goes to the positive side of your LED lights.
- 85 and 86 use electrical current to create a magnetic force, which then closes the 30 to 87 switch and allows the electricity to flow to your lights. Without this current, no magnetic force is created, so the 30 to 87 switch stays open, and your lights stay off.
- 85 connects to the power source that you want to control the switch. For example, you could splice a wire off your high beam switch wire or off your backup light wire
- 86 connects to a ground.
(Note: 85 and 86 can be reversed, but our harnesses have them setup this way).
What if I don't always want my LED light to come on with my high beams or backup lights?
Good question! So you'd want another switch on your dash that you turn off and on. When it is off, and you put your high beams on, your LED light will still be off and vice versa. In this case, you need to wire the dash switch in between the trigger current, i.e. the line you spliced off your high beam wire or your backup light wire
With our wiring harness, all you need to do is cut the wire coming from the switch to the 30 prong on the relay and wire it to your high beam lead or your backup light wire. That way, when you do have your high beams on, the current from that goes to the dash switch first, and if that is off, the electricity can't get to the 85/86 circuit to create the magnetic force to close the 30/87 circuit, which turns on your LED lights.
Check out our Wiring Accessories for harness extensions, rocker switches, and more.
Still have questions?
Check out our blog post about How to Know Which Off-road LED Light Bar Wiring Harness You Need
or our Wiring Harness Diagrams. If you're still stuck, we are here to help, send us an email or give us a call
Meet the Author: Extreme LED has been helping offroad enthusiasts with their LED lighting needs since 2011. We have built our company to provide you with the best experience from shopping to customer support and ultimately use and longevity of our products. Our high-performance LED Light Bars & Pods are covered by our Lifetime Warranty and with free shipping over $100, you can rest assured that you are getting a high-quality product that will provide long-lasting lighting for your vehicle.
There is a fuse attached to our wiring harness that he can switch out. If you are still having issues with it please send us an email and we will investigate further.
- Ciara
Extreme LED
My husband got a light bar for Christmas and when he first got it he hooked it up to the battery and later that night the light bar wouldn't turn on so I am trying to figure how he could hook it up to a fuse so if it blows out the fuse he could change just the fuse.
I installed a small light bar in the front and two small lights on the back. I used the pulse bar under the hood for the front one and the pulse bar under the head liner.
When i went to drive the winch won’t work unless I turned on the light bar in the front and all so the lights on the back came on. Also without the light bar switch on I didn’t have power to the windshield wiper. What did I do wrong.
the box has its own power and ground that control it all. please email me back at kylepollock03@gmail.com thanks
Thanks mingya
1 green and 1 black my relay has 5 connection. 30, 85, 86,87 and 87a. how do i wired the lights
My relay switch has 1 wire on each side with the fuse inserted (20amp. Is this correct?)
Please give me step-step instructions on how to wire the two LED lights to this relay, what amp should I use, and how to wire it so I use a toggle switch. I want these LED bars to turn on and off with the toggle switch.
However things are not quite working as they should. The new spot comes on with the low beams and turns off when I hit the high beams.
I have checked and the relay 'power' is spliced into the high beam wirs so that should only suppy power to the relay when i hit high beams.
Any thoughts folks? Could my relay be dodgy?
Paul
Thank you
I got a 50 in curved led light bar for my Jeep came with two pod led lights... do i need to buy extra black and red wire to hook up the pods? I’m having difficulty on to how those should be hooked up.
But only half of each aux rear lights light up.. each light has 6 LED's but only 3 on each are lighting up..
can anyone advise..
Instead, you'd need to splice a wire from your high beam wire to the 30 prong on the relay. Then if either the high beams come on OR you flip the switch, either one of those will close the relay and turn on the LED light.
Hope that helps!
Yes, you can do this; basically, you would put your switch in between the reverse wire and 85, so that the relay would only trigger when the switch was on (to make the connection to 85).
You could even do this: Get an SPDT switch, with center off, and wire the common terminal (center, usually - but check it first) to the relay (85). Now, wire one of the remaining switch terminals to your power source, and the other to your reverse wire.
Now, when you set the switch to the middle (off) position, your reverse lights operate as normal (and don't trigger your extra lighting). When you flip the switch one way, your reverse lights will operate the relay (and your light setup). When you flip the switch the other way, your lights will turn on independent of the reverse lights.
This is a simple modification that might be worth doing depending on your needs, because after all - who wants to redo their wiring if they don't have to, right?