Member Since: 12 Dec 2012
Location: Middletown, Rhode Island
Posts: 367
Double switch wiring for led light bars
Quick question, I already have a light bar on my LR3 and I have it wired directly to my battery using the harness it came with, and I have a rocker switch in the cabin which turns it on. I plan on getting a work light for the back. What's the easiest way to wire it for power? Can I just take the new harness I get with the new back light and splice it into the wires I've already used for the front light bar, red to red, black to black, and the 3 other switch wires to my other unused rocker switch? instead of adding more wires directly to my battery. Does that make sense? The harness comes with relay and fuses.Narpy's Grill Mod, Suspension Rods, Ultra guage, wrangler Goodyear duratracs 265/60/18, new thermostat, diff oils changed, brake switch new, aluminum rack floor, LED driving lights in foglights, rear camera, just need gvif unit, next on list! New front arb bushings, new front valve block, 191,000 miles.
12th Oct 2015 3:06 am
cmb6s
Member Since: 06 Sep 2013
Location: Herndon, VA
Posts: 73
Splice in to the positive wire running from your battery to the front light bar (between the battery and any fuse you may already have). You then run that to your new fuse (up to you whether you want to use a relay... personally, I wouldn't use one for a work light since I would want to be able to turn the light on while the car is off). You then come out of your fuse and into the switch. Then, out of the switch and into your work light. You can simply run the negative wire from your work light straight to any ground.
16th Oct 2015 8:45 pm
mx468
Member Since: 12 Dec 2012
Location: Middletown, Rhode Island
Posts: 367
!2 volt from rear port?
Hey cmb6s, when connecting the rear work light can I get the power by splicing into the one of the wires that goes into the 12volt port in back, instead of trying to get the wire all the way to the engine bay? I have the harness below for the led light. I would just cut the rings off the fuse/battery terminals and splice into rear lights, right? So all I would be left to do is extend the switch wires to my rocker switch I have already mounted up front, right?
Narpy's Grill Mod, Suspension Rods, Ultra guage, wrangler Goodyear duratracs 265/60/18, new thermostat, diff oils changed, brake switch new, aluminum rack floor, LED driving lights in foglights, rear camera, just need gvif unit, next on list! New front arb bushings, new front valve block, 191,000 miles.
19th Oct 2015 4:21 pm
tlt
Member Since: 02 Sep 2006
Location: Austin, TX
Posts: 262
Last edited by tlt on 21st Oct 2015 3:37 am. Edited 1 time in total
19th Oct 2015 5:48 pm
cmb6s
Member Since: 06 Sep 2013
Location: Herndon, VA
Posts: 73
So, the problem as I see it is that if you splice into the rear power port, the work light will be on a switched power source. The same is true if you use that wiring harness with no modifications. If you do both (splice the wiring harness into the power point), now you have TWO relays controlling one light.
I have a rear facing work light as well and I can tell you that if/when I use it, it is often with the car off. But that's up to you. It should work fine to do what you described, but the pros and cons as I see it are:
Pros:
1. Easy and quick to wire up
Cons:
1. You now have four failure points in one circuit (the fuse for the power port, the fuse for the light, the relay for the power port and the relay for the light)
2. Probably not a big concern with an LED light, but you are now putting additional load on that circuit (I don't remember what it's designed to handle)
If you want to do it that way, it should work. I don't know where you plan on mounting the switch, but if it's going to be on that back left cargo panel, then both tlt and I could probably show you mounting locations that would work well (I got three Carling Contura type switches in there ok).
Something else to consider is whether you ever plan on running any other electrics in the back (e.g. I have a cell phone booster, two anderson PP connections, and extra cig outlet, some USB outlets, a rear work light, etc.). If you plan on adding anything else, it's probably easier just to run a thicker gauge wire to the engine bay now and set up a small fuse box in the back, which you can then tap into for your light.
19th Oct 2015 6:05 pm
mx468
Member Since: 12 Dec 2012
Location: Middletown, Rhode Island
Posts: 367
New Fuse box in engine bay
That was my other option. I was planning on possibly putting together a fuse box in the engine bay where I would be able to connect any other accessories I might add down the line. Would be much cleaner and I wouldn't have tons of wires attached to my battery. Where is a good place to get a fuse box? A marine store like West Marine? Thanks for the help and suggestions.
I already have a rocker switch mounted up above near my interior roof light to use for the rear worklight. Just need to wire it to the new harness.
As for using the light when the car is off, my front lightbar is connected directly to the battery and works when the trucks off. So my rear led worklight should be able to turn on when the trucks off as well. If its connected directly to the battery.
Narpy's Grill Mod, Suspension Rods, Ultra guage, wrangler Goodyear duratracs 265/60/18, new thermostat, diff oils changed, brake switch new, aluminum rack floor, LED driving lights in foglights, rear camera, just need gvif unit, next on list! New front arb bushings, new front valve block, 191,000 miles.
20th Oct 2015 6:32 am
cmb6s
Member Since: 06 Sep 2013
Location: Herndon, VA
Posts: 73
I just purchased my stuff off of Amazon, but West Marine would work as well. I got a Blue Sea fuse box and a Hella relay box. However, while all of my connections and cables are high quality, it's quite a messy spaghetti mess behind my cargo panel. If I had to do it all over again, I would most likely try the Bussmann 15303-5. Seems to be a pretty elegant solution to fused circuits where some relays are needed.
22nd Oct 2015 2:49 pm
mx468
Member Since: 12 Dec 2012
Location: Middletown, Rhode Island
Posts: 367
Battery Terminal Connector from West Marine
I ended up getting these. $20.00. I have the new light harness and it has the relay and fuse on it. I plan on running the wire from the engine bay to the back and out to my rear led light. I'll post some pics when I'm done.
What size wire/gauge should I use for my lights. Its a 7" led light bar, 36 watts. Would 16 gauge be sufficient?
Narpy's Grill Mod, Suspension Rods, Ultra guage, wrangler Goodyear duratracs 265/60/18, new thermostat, diff oils changed, brake switch new, aluminum rack floor, LED driving lights in foglights, rear camera, just need gvif unit, next on list! New front arb bushings, new front valve block, 191,000 miles.
23rd Oct 2015 5:43 am
cmb6s
Member Since: 06 Sep 2013
Location: Herndon, VA
Posts: 73
If all you've got on the circuit is 3 amps or less, then yes, I think 16 awg should be fine for that run. I tend to over-engineer and would use 14 awg if the cost difference isn't much, but I think 16 awg would still result in less than a 5% voltage drop.
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