Wsullivan1221

I just purchased a few aux lights and need help on figuring out which harnesses to use for them.

The two simple ones are 4 2x4 18w light pods that are mounted at the lower windshield pillars. The other is a 300w 50 inch light bar that will be mounted at the top of the windshield.

The more difficult situation is a 20 inch 126w light bar that I'm mounting in the back. I'd probably need about 15 ft of wire. Rigid Industries has the harness for it but I don't know if the wattage or voltage would fit it correctly.

Would the harnesses that Ridged Industries offers for light pods and light bars work for the front lights?

Lastly, I am still confused on how to install the switches. Do I need to buy a seperste set of switches or do the harnesses come with them? If they do, do you recommend buying other switches separately?

Any input is appreciated

*I got no replies on Jeep Forum*

JK505

Did the lights not include the harness when you bought them, what did you receive in the package?

All the lights I've bought came with the harness and switches but the switches were cheap looking. I bought a few OTRATTW (Over the river and through the woods) switches that I'll be hooking up within the next week. You do not necessarily "need" a harness, depending on what the lights you bought are set up like. (Pictures would be helpful)

Once you get everything on hand, I'd be willing to help with the install depending on what part of VA you're in.

14Sport

As JK505 said, the lights usually come with harnesses.

To determine what amp harness you need for particular lights, you can use the formula:

Watts / Volts = Amps. You also want to add a 20 to 25% safety factor into the rating of the relay, switch, wiring, and fuse.

So each 18W is drawing around 1.5 (18/12) amps or 1.3 (18/13.8) amps depending on which voltage you prefer to use in the formula. I always use 12 for voltage as I like the built in safety factor.
So the total of the 4 lights would be around 6 amps. Add the 20 to 25% safety factor at your at around 8 amps so you need a harness rated for 10 amps (not sure they make an 8) for the (4) 18W fixtures.

Continuing with the formula, the 300W light bar draws 25 (300/12) amps. With a 20% safety factor you need a harness rated for 30A.

For the 126W light bar for the rear, it draws around 10.5 (126/12) amps. So make sure the harness is rated for 15A.

You can also build your own harness. If you go this route, make sure everything is rated properly. We've already determined the amp ratings for the relays, switches, and fuses. The wire gauge will depend on the draw and length. Here is a chart to make that part easier.

Amps and Wire Gauge - 12V Circuit

I also prefer the OTRATTW switches. Having a bunch of little red switches stuck around the cabin does not look clean to me, although some guys have done a good job of making them look pretty good.

Hope this helps.

JK505

I was just going to suggest 12 gauge wire but that works too! Haha. It wouldn't take much work at all to create your own "harness". If the lights didn't come with one, it'd be easy to make the circuit complete with some basic materials while still preserving a nice look.

Edit: I highly suggest OTRATTW, though. They look sharp

Wsullivan1221

Here are is a pic. 300w light bar hasn't come in yet. That formula definitely helps. What do I do about the rear lights though? I can't find anything that would extend to 15 ft

14Sport

If you can't find that size harness then you will need to make your own. And also I forgot to mention, if you use relays the control circuit runs on milliamps so the switch and wiring for that circuit can be very small. You only need a switch rated for the amps of the light circuit when not using a relay.

I've attached a typical wiring schematic you could use for making the rear harness. It shows 3 lights but you can adapt it for one.



Edit: The chart shows length of wire running from the battery to the light and back again. So you want to use 30' in the chart which would be 8 gauge wire for the load circuit (Pins 30 and 87) and the ground return to battery. The control circuit (pins 85 and 86) can be 20 gauge.

14Sport

The 12 gauge would work for the pillar lights.

14Sport

I try to explain it in a little more detail since I have time right now.

Load Circuit

1. You want to run (2) 8 gauge wires from the battery area back to the rear fixture, one for power and one for ground.
2. Connect the power and ground wires to the fixture.
3. Returning to the battery area, you don't want to connect the power wire directly to the battery. You will be placing your relay and fuse in this wire.
4. Find a good location to mount the relay along the path of the power wire.
5. Cut the power wire at the relay.
6. Connect the side of the power wire that comes from the light fixture to pin 87 of the SPST(single-pole, single-throw) automotive relay.
7. Attach the other side of the power wire that runs toward the battery to pin 30 of the relay.
8. On the battery side of the wire from pin 30, attach a fuse holder.
9. Attach the other side of the fuse holder to the battery positive.
10. Connect the ground wire from the fixture directly to the battery ground.

So now the power wire should be coming from the battery to one side of the fuse holder, out of the other side of the fuse holder to pin 30 of the relay, and out from pin 87 of the relay to the light fixture positive. The ground wire goes directly from the battery ground to the fixture. You have now completed the load side of the install. All that is left is the control circuit.

Control Circuit

1. Run a wire from pin 85 to the location inside the tub of your switch.
2. Connect it to one side of the switch.
3. Run a wire from the other side of the switch to the nearest ground lug in the tub.
4. Connect pin 86 of the relay to 12V power source (either switched or unswitched, depending on your needs).

This completes the installation.

RC3

I would ground the light bar to the frame of the Jeep and eliminate 1 run of wire to the back of the Jeep. Copper wire is expensive these days.

14Sport

Yeah that's how I drew it in the schematic but I know most harnesses that come with the lights return to the battery. I was trying to mimic that but as long as you have a good ground either way will work.