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Demco 4-Diode Universal Towed Vehicle Wiring Kit Installation - 2003 Jeep Wrangler

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How to Install the Demco 4-Diode Universal Towed Vehicle Wiring Kit on a 2003 Jeep Wrangler


Hey everybody. Rob here, at etrailer.com. Today we're going to be taking a look at the Demco High Powered Diode Wiring Kit on our 2003 Jeep Wrangler. Now our diode kit is going to allow us to use the signals from our motor home and transfer them to our Jeep's actual tail lights. That way when we're flat towing our Jeep, everyone around us knows whether we're changing lanes, slowing down and we have our tail light function when we're driving at night. Another nice thing about our diodes, aside from the fact that they're going to get us our, signals to the back of our Jeep, they're also going to protect our Jeep's electrical circuits because they're going to prevent any kind of back feeding or anything like that, if there we're a problem on the motor home end.

The diodes are only going to let electricity flow one way. So they're not going to allow any kind of back feeding or problems to occur.And whenever you are flat towing, it is important to have your lights and your signals at the back. Because again, we all want to know what's going on around us and we want to make sure that people driving around us know what's going on.Now, there are different ways to get those signals to the back. One way is magnetic lights. We've all seen those, where they're usually stuck to the top and they do work but that's going to require us to run a wire all the way to the front of our Jeep, to the back of our motor home.

So that just means that we're going to have a wire dangling in the wind, potentially scratching the paint, getting caught on something and we're going to have to set it up and take it down each time. The benefit of the diodes is, is once they're installed, we don't have to worry about it anymore. And they're not going to affect our Jeep when we're driving it like normal. All the lights are going to work when we're towing and then the Jeep's lights are going to work normally, just like they would from the factory when we're driving around.Another downside to the magnetic lights is, let's face it, we have a soft top on our Jeep here and there's only so much metal that we have to put the magnetic light on. So you'd end up having to put it on the body somewhere down here.

And we really couldn't put it up here because there's no metal to attach it to. Now there is a different option as well, as a bulb and socket kit but that's going to require us to drill a hole into our factory taillight and put a separate bulb inside. Now that will bypass the entire electrical system, which is nice. But again, it involves us to drill a hole into our tail light, which can over time eventually leak and cause problems inside.So I personally like diodes because it's a one-time installation with no additional setup. And the diodes are going to come, with most, everything you need to get it installed.

It's going to come with all the diodes, connectors and a good length of wire. We actually had quite a bit left over when we wired up our Jeep. However, the wiring is going to have a 4-pole flat connector on the end of it. And I actually suggest upgrading to a 6-way because it's going to give you two additional circuits. So if you have a braking system that has the monitor light or if you have a charge line, you want to make sure your Jeep's battery is staying charged while you're towing it. That 6-way is going allow you to use those two extra circuits. And we chose to do that.We have a 6-way round on the front and actually using the Demco coiled cable. I like coiled cables just because, especially on tow bars that don't have the channels, it gives you the slack you need when it needs to extend. But whenever we don't need that extension, it coils up nice, neat little package. It's going to prevent it from dragging on the ground and getting damaged. And again, a 6-way is going to provide us those additional circuits, if we need them.And our Demco kit does come with a metal socket, which is actually pretty nice. It is silver. So it doesn't blend in very well. But again, it is metal. So over time we don't have to worry about the sun making the plastic brittle and that lid opening and closing is not going to cause any damage over the long run because it is metal and is going to withstand up to most of the environmental issues we may see. Whether it's rain, extreme sun or cold temperatures. The cord itself is going to be coiled, so we'll have plenty of slack to get hooked up. And then again, come into a nice, neat little package when we don't need all that length. One end is going to be a 7-way, it'll plug directly into our motor home. And then the other end is going to be the 6-way, plugging into the socket that comes with the kit.Now, as far as the installation goes for the diodes, it's actually pretty straightforward. We're just going to run a length of wire from the front of our Jeep to the back, towards the tail lights. And then we need to splice in and make the connections. And it can seem a little daunting to some people, make them a little bit nervous but rest assured it's not complicated at all. It's a very straightforward process. And we actually did run into a little bit of an issue. This is an older Jeep and most likely a lot of people have worked on it and a lot of different things have happened. But that's not a problem because we still went through and did all the testing we needed to do, so that our diodes would work properly. In fact, let's go and bring it in the shop, make sure you feel comfortable and we'll show you where and how we tested everything and even how we wired up the plug on the front of the Jeep.To begin our installation, you want to start at the front where you're going to be mounting your electrical. Now we have a spot on our base plate for our electrical, mounted up. So I just went ahead and zip tie my wiring and kind of left myself a little bit of a loop here so there's enough to work with. Now you want to route this back towards the tail lights. So I ran my wire just across the base plate. And then I went to the outside of the frame and went in between the base plate and the frame and came right over to the side of the frame here. Now there's a hole right inside of the frame. So I took advantage of that and I actually started routing my wire inside the frame, so it's nice and protected. Now an easy way to do that is if you have a coat hanger or a thick piece of wire, something like that, you can put it in the frame and feed it down until you can get to another hole in the frame and just keep leapfrogging down the way.So we routed it along the frame. And again, right behind the front tire, there's a pretty large hole. It's not too far away, so I had my wire come out, pull the slack, feed it in and continue to. Routed it down the frame. And again, here's another hole that we used to kind of bring the excess slack out. Go back in the frame, continuing along, kind of leapfrogging down until we came all the way to the back of the frame, behind the rear tire here. And here, you can see where my wiring came out. Now there's a couple of different ways that we can get this hooked up. One way is that we can actually remove the tail lights and we can pull all the wiring out. However, on your Jeep you should have this liner here, that's part of the wheel wall liner. Now ours is actually missing the fastener that's holding everything in place. But if you grab it, we can pull that panel down, kind of bend it out of the way and we can get access to all of our tail light wires through this opening.Now you're going to notice that there's quite a few butt connectors and splices already made and that was from the trailer wiring. That's on the Jeep. Which helps us out a little bit because it is going to help identify the wires because the trailer wiring's already hooked up. So if we know that it is hooked up correctly and it is working, the left turn signal, the right turn signal and the tail light wires should be identified for us. But we're going to go ahead and test our wires to make sure that they are correct. And we can identify the color of wires on the Jeep side that we need to connect to.Now on the end of your wire, where you're going to have that 4-pole connector, we don't need that because that's actually going to be tying into the wiring. We're not plugging it in. So I went ahead and cut the end of it off, but now we need to separate each one of our wires as high up to that last point as we can, so we have four separate wires. Now once you cut that 4-pole off, you're going to have a little bit of separation at each wire, which will help out because we can just grab the wire and start pulling. And again, going as high up as we can, so we have four separate wires. So I'm going to go ahead and split these until they're all separate. So at this point I went ahead and turned my tail lights on so that we can identify the tail light function, wire color. Now you don't want to have any turn signals, the brakes or any other light function on, so we can really isolate that signal and make sure we have the correct wire.And again, the trailer wiring is going to help us out a little bit because our tail light function is working properly on the wiring but we're still going to test and make sure that is the proper wire, that it's hooked up to. So we're getting our signal from the black wire that has a yellow stripe on it. Now it is maybe a little bit difficult to see, but if we look inside this opening, there is a connector that we can see that our trailer wiring is connected to but if we follow the wires up, we can see that it actually goes into the back of the Jeep and that's going directly to the tail light. So we want to put our diodes and our connections as close to the tail light as we can and make sure that it's on the taillight side and not on the trailer wiring side.Now here, over on the passenger side, we have the same colored wire and right above the frame, we actually have quite a bit of wiring that's going to go up. But as you can see, there's not only an opening. It goes over the frame and up higher to where we can't see but we can make our connection on the passenger side using this bundle of wire. So now we're going to lower our Jeep back down, turn the tail lights off and we're going to get an extra set of hands so we can identify the brake color wire on each side.Now on the left side, we're getting a signal from the green wire with a red stripe on it. So that's going to be our left-hand brake and left-hand turn signal wire, since our Jeep uses the brake and turn signal off of the same wire. And we're going to go over to the passenger side and verify the color of wire over there. And over on the passenger side, the brake light wire and the right turn signal wire is going to be the brown wire with a red stripe. Now again, you can find this bundle of wire right underneath the rear bumper, just underneath the taillight here. So it's a really easy spot to access all the wires we need. And whenever we're done making our connections, we can tie everything up and it's out of the way and we can make sure it's nice and protected.So to start out, we're going to start with our left turn and our brake light wire, which is going to be the red and green wire. And again, you want to go on the tail light side of the wire if you also have trailer wiring installed. Now it may be a little bit difficult to see, just because I had to have my hands in here and it's up inside the body here. But what we want to do is cut this wire in half and then we want to install a blue spade terminal on each end of the wire. So I'm going to go ahead and do that and then we'll show you what it looks like when I'm done. Now that we have spade terminals on both ends of those wires, we can grab one of our diodes.Now the diodes are going to be labeled. You'll see that there's two in terminals and one out terminal. The out terminal needs to go to the tail light or the terminal and the wire that's closest to the tail light and the one furthest away is going to go to the in terminal. Doesn't matter which one at this point, we just need the one furthest away towards the front, to go to the end. And the one closest to the tail light to go to the out. Just plug them in like this. Just a little bit of a tight fit but that's a good thing, we don't want those terminals slipping off. And the other terminal that's open, we're going to take our yellow wire since we're on the left-hand side and we're going to trim off the excess, rout it up to this section here and install the other spade terminal. Let's strip back the end, slide it onto the wire and we'll crimp it down. And we'll take it, I'm just going to plug it in to the other end of the diode, making sure that it's seated all the way on the terminal.So we should have a yellow wire and the factory wire going into the ends and then going out to the tail light. For our taillight wire, that's going to be the brown wire. The diodes going to hook up exactly the same. We'll have the brown wire going to the end. And then the farthest section of that black and yellow wire will be going in. And then the one closest to the tail light, will be going back to the tail light. So we're going to go and get this one in place as well. Now I like to give myself a little bit of excess. You can see, I gave myself quite a bit with that yellow wire. I'm also going to do that with the brown wire, give myself quite a bit of excess. I'm going to cut the wire so we can get ready to hook our spade terminal in. However, we want to hold on to the excess brown wire because we are going to be using this to go over to the passenger side. We'll go ahead and strip back the end and get our spade terminal crimped in place.Then we can grab our diode and get all the terminals hooked in.Now the reason why we held on to the excess brown wire is because we actually need to attach it to the existing brown wire here, so we can jump that signal to the passenger side, tail lights so they both come on at the same time. Now in your kit, they are going to provide you with a quick splice and the way these work is you can just slide the wire into the quick splice, take your new wire, slide it in place and then you crimp it down. Now this will work perfectly fine but I would like a little bit more protection from our wires. So instead of using the quick splice, I'm ready to replace it with a butt connector, a heat shrink butt connector and just splice it in. So I'm going to cut my wire, strip back all three ends and combine them into this butt connector. Have a little bit more protection and prevent any kind of corrosion or anything happening to a wire inside.So let's strip back all the ends of our brown wire. I'm going to combined two of them together, take my butt connector, put them into one end. And that's also a reason why I'm using this size butt connector, this is actually for 12 gauge wire, but it's a lot easier to get two of these wires inside rather than trying to cram them in the proper size butt connector. We'll crimp it down. We'll take the other end, put it into the open end of the butt connector. Just going to take a heat gun and shrink down that connector. If you're using heat shrink butt connectors and you're shrinking them down, I do want to mention, if you are using an open flame like a torch or a lighter, anything like that, you've got to be extremely careful not to burn or char the connector or the wires.So now we want to take our newly extended brown wire and the existing green wire. And we're going to route them over to the passenger side, where we tested our wires and make the connections over there the exact same way we did with these diodes. Now I do want to mention, when you're routing your wiring, obviously we've protected the wire going through the frame. You may not have that option. You do want to stay away from the exhaust or any other moving parts that may damage the wire. But we're going to go and route these over there and make our connections.So I went in and rounded my wire over the fuel tank. So again, it would help protect the wires. Then use that same method of using a pull wire to get them from this side to the other side. Here you can see the wires coming over the fuel tank and we made our connections just like the other side. Now we do have one more wire we need to connect and that's going to be our white wire. Now this is going to be our ground. So they do provide us with a ring terminal as well as a self tapping screw, so we can find a nice solid piece of sheet metal and make sure it's a solid ground. Now fortunately for us, our trailer wiring actually has a really solid ground going right into the frame, right here. So I'm actually going to remove the self tapping screw or bolt that's in there now and put my ground right here so we can prevent having to put any more holes in the frame of our Jeep.So I'm going to pull that out. We'll trim our ground wire and attach the ring terminal. And again, I kind of like to give myself a little bit of slack so I can tuck everything away, tuck it up as high as I can. So I'll put a little loop in there, trim off the excess, strip back the wire and crimp the ring terminal in place. Go ahead and grab that bolt again and put both of the ring terminals in place to make sure that both of them are grounded. Make sure that our wire will fit. And then we'll reattach at the ring terminal.Now whenever you do put in any self-tapping screws, especially for grounds, you want to make sure they're secure. That ring terminal isn't going to spin but you also don't strip out the screw itself. So now that everything's connected, I'm going to come back and clean up all the wiring. I'm going to tie up anything that's loose. And as well as all these exposed wires, I'm actually going to come back, put some wire loom and some electrical tape on it to help protect it and also hide these colored wires from showing on the outside. And once you have everything cleaned up and you're satisfied with the way everything looks and that the wires are protected, you want to test the circuits and make sure they're working properly. So I'm going to grab my tester and run through the functions and verify that we are getting the correct signals back here.So if I turn my tester on, we can see that my taillight function is working. The left turn signal, my brake lights and the right turn signal. Now we're not going to be using the 4-pole on the front of Jeep because we're actually going to be upgrading to a 6-way, so we have a few more functions available to us. So we're just going to go ahead and cut the wires as close to the connector as we can, so we don't lose any slack. And we can get rid of the end of the connector. Now we can grab the socket. We'll go ahead and pull the rubber boot off. Going to take the wires, putting them in through the small end, coming out at the large end and you just push it out of the way for now. Now we want to strip back a little bit off of each one of the wires.After we grab our socket, we look at the back, the terminals are going to be labeled but you do need to pay attention to the direction of the arrows because they're not going to be directly in line with the terminal. So if we start at the very top and see the arrows pointing towards it, top one is going to be LT for left turn. For you to move clockwise, the next one is going to be RT for right turn. The next one is going to be labeled S, that's going to be your electric brake signal, then TM for trailer marker. Then the large terminal is going to be your ground. And the center pin is going to be the auxiliary 12 volt power source. So if we go in the same direction, starting at this one here. Excuse me, starting at the top, it should be the yellow wire, then our green wire. We're not going to have one hooked up here. Then we'll have our brown wire and our white wire hooked up, with our-pole wire right here.Now also for the terminals, the set screws are actually going to be on the side, kind of recessed. So a precision flat blade screwdriver is going to be your best bet to get in there and be able to loosen those terminals up. So we just want to loosen that screw up and you can see inside, how it's moving out of the way. I personally, don't like to take these all the way out because they are very small screws and extremely easy to lose. So we loosen that one up. That's LT for left turn, so we'll take our yellow wire, put it inside the terminal. And I like to leave just a little bit of the copper exposed, not enough that it's going to cause any kind of crossing over arcing issues. But just so that I know that the copper is in there and the insulation's not going to cause any kind of connection issues. Want to take our screwdriver and we're going to tighten down that set screw, give it a quick tug, make sure the wire is secure. Now we're going to go through hooking up all the wires to the corresponding terminal.We tested our socket, according to the labels that we had it hooked up to and we found out, the functions are not labeled correctly. So if you look at the top of the socket, that should be your trailer marker and going counter-clockwise the large ring terminal or the large terminal is going to be for your ground wire. Then next to that, you'll have your left turn and then your right turn. So at the one o'clock position, it should be open and the center pin should be open, but this is the correct way to wire it up. And it does work with the umbilical cord that comes with the socket.And once we have all the wires hooked up, I like to come back and I like to fill this entire area with dielectric grease. And that's hopefully going to prevent any kind of moisture from sitting inside and letting corrosion build up. Just get a good amount inside, making sure it fills all the holes. Then we can take the boot. We'll slide it over the terminals. Make sure it goes all the way over. And then I'm also going to come back and I'm going to wrap the back of the socket, the boot and these exposed wires with some electrical tape. Not only to help keep it in place, seal it off but also to hide some of these colored wires here.Now to mount our plug for a base plate, I'm just going to use a couple self-tapping screws that actually came with the base plate because the socket and cord do not come with any hardware. Let's get them lined up and take a nut driver. And use, to secure one side, make sure the other side is lined up.But again, I'm Rob, here at etrailer.com and that'll finish up your look at the Demco High Powered Diode Wiring Kit on our 2003 Jeep Wrangler.


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