Imjosiah

Hey guys, here is what i got. i mounted two flush mount off road LED in the rear bumper and two on the side rear. I want to wire them with a switch to turn on any time. but also to come on when i am in reverse.

I know i can just tap into the reverse from the tail lights. I know i can run a switch, but i don't know how to do it all together. from what i read i "think" i need a five point reley, but i am just more confused reading online.

can someone who knows just draw me a schismatic. i can't find a clear one online.

thanks a ton. will post photos once lights are all set up. with light bar, two winch floods and these four in the back, lol should look like a space ship.

denverd1

a 4 pin relay would work. just run the switch wire and reverse light wire to the same pin

denverd1

relays:
http://www.offroaders.com/info/tech-...ive-wiring.htm

Turbo X_J

Don't run 2 positive wires to the same point without diodes.

BlueRidgeMark

NO! NO! NO! NO! NO!



Bad mojo.



That guy has no clue what he's talking about. He's not always wrong, but he's wrong enough you should never take his advice.


If you want to learn about relays, go here.


Josiah, give me a few minutes and I'll work it out for you and post it here. I did it a while back but I forget the details. I do remember you need multiple relays.

What's the current draw of your LEDs?

JandDGreens

This is interesting because I ("I'm no expert either") would think you could piggyback off the hot wire that goes back to the original back up lights (that would also make it so that it is switched with the ignition also???) and use it to trigger the relay that would be needed to run the additional back-up light you want to install. I would think that as long as you have fuses in the lines matching the size of wires you are using there would be less risk in a problem????

After reading his post again I realized he wants it switched so they aren't always on but I figure just run that wire through a switch before it gets to the relay???
I'm basicly Subscribing to learn something.

BlueRidgeMark

Okay, here we go. I'll try to explain the whys of this so that others can learn. First of all, why NOT just run the switch and the reverse light to the same pin?

Do you want the reverse lights to come on every time you flip the switch for the LEDs? That's what would happen. It's just never a good idea to build a circuit that can backfeed, which is what you are doing if you have both switched circuits going to the same terminal on the relay. Also, depending on how the reverse light circuit is set up, you could possibly have a short.

Just don't.

Okay, so what SHOULD you do?

Let's start with a diagram:





Alright, let's see what we have here.

First, we have one LED representing ALL of the LEDs you want to switch. If they are all going to go on together, you just hook them in parallel.

Relay # 1 is providing the heavy power to the LEDs. Find out your current draw for each light, add them all up, and make sure your relay can handle that amperage PLUS some. 20% is a good margin. When in doubt, go bigger. 30 amp relays are easy to find.

Relay # 2 is acting as the referee between the reverse lights and your manual switch. It will keep them from bothering each other. Activate either one, and the LEDs will be turned on.

Where you see a brown arrow pointing down, you have a ground connection. I'm not showing the switch or the reverse light circuit. I'm only showing the wires coming from them. You'll wire 12v to your switch, and of course you'll fuse it. You ALWAYS fuse every circuit!

Same for the 12v going to Relay #1. You need a big fat wire to feed that thing, and you need to fuse it near the battery. Do NOT take that power from your fuse box! You'll burn something up. You can go to the terminal where the battery connects to the PDC. That's a good spot to get serious power. Size your wire and your fuse to handle the current draw. There are plenty of sites online that will tell you what size wire to use. You need to plug in the length of the conductor and the current it will draw. Always round up. But don't get ridiculous! There are a lot of Jeeps out there carrying around a bunch of expensive and heavy copper that is NOT needed just because somebody wanted to brag about having double aught battery cables. Size it by the tables, maybe go one size up, and you'll be golden.

Next up: how it works.

BlueRidgeMark

Let's talk about relays. A relay is just a switch. That's all it is. It's operated by an electromagnet. Put power to the electromagnet, and the switch flips. Simple. We get to control some high power with a little bit of power. That's useful, but the really fun things happen when you understand all the different ways you can make relays work together.

Let's look at Relay #1.

• We have "12v supply" going to Terminal 30. That's your heavy wire coming from the battery.
• Terminal 86 is grounded.
• Terminal 85 goes wandering off to Terminal 30 of Relay #2. More on him later.
• Terminal 87 goes to the LEDs. This should also be sized for the current and distance.
• Terminal 87a is not used.

So, when we apply power to terminal 85, current flows through the coil, to ground (Terminal 86). This current is very small - usually about a quarter amp or so. (Yes, you do need to fuse this if it's not coming from a fused source!) The coil becomes an electromagnet, and pulls a spring-loaded lever so that Terminal 30 is now connected to Terminal 87. Current flows from the battery, to Terminal 30, through the high current connectors inside the relay to Terminal 87, then out to your LEDs. Lights! Yay!

That's it! Simple, isn't it?

Next up, Relay #2.

Ad-HocXJ

All you need my friend: (With options )

BlueRidgeMark

Okay, Relay # 1 was simple.

Relay #2? That's weird.... /scratching head..../

No, it's not weird. Let's walk through it. First the connections:

• Terminal 86 is grounded.
• Terminal 85 goes to your switch (on the dashboard, I guess?)
• Terminal 87 also goes to your switch (which means, it goes to 85 as well. Yes, a short jumper between them will work just fine).
• Terminal 87a goes to your reverse lights. Find a good place to splice in!
• Terminal 30 feeds into Relay #1, Terminal 85.

So how does this work? Let's trace it out.


Starting out, nothing is turned on. No current flows anywhere.


Now, let's flip your dashboard switch on. What happens? You're feeding 12v to one side of it, and the other is connected to Terminals 85 and 87 of Relay #2. Since 85 is the coil, current flows in the coil, the magnet is energized, and the contactor is pulled away from 87a and makes contact with 87. So, 12v flows from your switch to terminal 87 to terminal 30, and from there out to Relay #1, Terminal 85. This energizes Relay #1, the contactor is pulled over to Terminal 87, and 12v flows from the battery through Terminal 30, to 87, to your LEDs, and things get bright!


Now, also notice what happened to the reverse lights. Before we flipped the switch, they were connected to Terminal 30 of Relay #2, and from there to Terminal 85 of Relay #1. But when we flipped the switch, that got disconnected. Your reverse circuit is safe, because it's no longer connected to any part of your LED circuit. Yeah, that works!


So let's flip the switch off and try the reverse lights. Back to our starting position. But now, we throw it in reverse. The reverse lights are lit, which means that there's 12v going to Terminal 87a of Relay #2. Oh, wait, that's going to Terminal 30, which then goes up to Terminal 85 f Relay #1, and we know what happens now. Bright lights!




So there you go. Flip the switch, and the reverse light circuit gets disconnected while the LEDs go on. No backfeed, no problem. Throw it in reverse, and there's still no problem - the reverse lights are simply not connected. Now shut the switch down, and the reverse lights trigger the relays to light your LEDs.





Clear as mud?


Nah, it's simple. Just take your time and walk through it. One. Step. At. A. Time.



Holler if you have any questions.

BlueRidgeMark

By the way, Relay #2 can be a lightweight. 5 or 10 amps is PLENTY. Relay # 1 will have to be sized to handle the total current of all of your LEDs.

Search on Fleabay for "Ford relay" and you'll find you can pick up good quality 10 amp relays for 10 bucks for a pack of 4 or 5. These are good quality relays that can be used in a ton of ways.

JandDGreens

__________________Courtesy of ;Ad-HocXJ


So this is what I was thinking you could do except put a switch between the Splice and pin #86. That way the aux. back up light would only be triggered when the vehicle ignition is on and the auxiliary switch is in the on position. and the original back up light would not be affected.
"Please tell me what kind of issues this would present."

I went ahead and wired my auxiliary coolant fan through a switch. The main thing I was concerned with is when doing it I made sure to use a rely that matched the power of the fan and that the wiring is adequate to support the flow of current. And fuses between each power source. 5 amp for switch and matching 40 amp fuse to 40 amp rely for the power source. Some recommend 60 amp rely for aux. fans.

Ad-HocXJ

Alright so I think this is what you want. Also a normal relay should be fine for your lights. Some info on the lights would make this easier.

LiamLikeNeeson

I want to do this but just for the stock reverse lights. I just want a 3 way switch that has them ON manually OFF all the time and REVERSE for only when reverse is engaged. How would I wire that up? And what lengths should new wires be if I need them?

neverenuff

what are chances that the diodes fail? which has a greater chance at failure the diodes or relay? the relay can fail open or closed , if the diode fails would that led to a short in the system?