A common question we get is, "What is the relay for and how do I wire it up?" So here is an overview of what a relay is, why you likely need it, and how to wire it up.
What is a Relay?
A relay is an electrical switch. It allows a low current "switch" circuit to control the electricity flow of a 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 to your LED Light bar), if you just put a switch between the battery and the light, it will have to be rated for the full current (amp draw) of the light. Our lowest amp draw LED light pod has an amp draw of about 1.4 amps. Many switches would be able to handle that...but if you are using, say our 50" LED Light bar, that has an amp draw of about 17.2 amps, which may be too much for that little switch to handle. As a result, you could end up overheating the switch, melting the wires, and reducing the current that is getting to your lights, making them not as bright.
Check our our selection of LED Light Bars
Another reason you may want a relay is for the creative ways you can use electrical currents from things other than a physical switch. Let's say you want have your LED Light Bar come on with your high beams, or reverse lights, for example. Read more about that below.
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 switch, you don't need to know what any of this is, because it comes all pre-wired and plugged in together.
But if you want to use some sort of electrical current to activate your LED lightbar, like make them come on when you turn your high beams on, or your reverse lights on (if you are adding LED backup lights), then you'll need to do a bit of rework.
First, let's explain the what these 30, 85, 86, 87 numbers are. Let's start with a 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 - connect to the power source that you want controlling the switch. For example you could splice a wire off your high beam wire or off your backup light wire
86 - connect 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.