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Curt Universal Tail Light Wiring Kit Installation - 2017 Ford Focus

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How to Install the Curt Universal Tail Light Wiring Kit on a 2017 Ford Focus


Hi there, Focus owners. Today on your 2017 Ford Focus we're gonna be taking a look at and showing you how to install Curt's Diode Wiring Harness. A diode wiring harness will take all the lighting signals from your motor home and give you a connection at the front to transfer those signals back here to the lights at the back of your vehicle. This way the lights will mimic your motor home when you're driving down the road. So everybody behind you will know your intentions. Now diode wiring is my personal favorite way to get lights on your vehicle.

We have different manufacturers, such as Demco and Roadmaster that also offer this. There are other options though, such as magnetic lights where you can just stick them on top of the vehicle. That's a quick and easy way where you don't have to do any modifications to your vehicle. You just have to set them up every time you want to flat tow. So if you don't want to do any setup, I'd recommend this.

If you don't mind doing the setup and you don't want to modify the vehicle, go with the magnetic lights. The last option is bulb and socket. We actually drill a hole inside your taillight assembly and add an additional bulb. This is only gonna work on certain vehicles depending on the room that you have available in your taillight assembly. It will work here on your Focus, but that's my least favorite option, as drilling a hole in your assembly does allow for moisture to potentially enter in later on down the road.

And to me, it's just a lot of modification, and there's just better options out there. I prefer the diodes just cause it's so much easier. And it works with the factory bulbs that you've got in there. There's five main components you'll need when flat towing your vehicle behind your motor home. You'll need your tow bar, which is the connection between your motor home and your vehicle, your safety cables, which is a supplemental connection in addition to your tow bar in the event of a catastrophic disconnect.

You'll need your base plate, which provides the attachment points for your tow bar and safety cables. You'll need your diode wiring, which takes all of the lighting signals from your motor home and operates the lights at the back of your vehicle so people behind you know your intentions when going down the road, and you'll need your supplemental braking system which will apply the brake in the vehicle when you hit the brake in your motor home to help you come to a safe and smooth stop. We'll begin our installation here at the back of the vehicle. With the trunk open, we're gonna remove both the driver and passenger side taillight assemblies. To do that there's a cover just on the inside that we're gonna remove. And you can just grab this cover. There's an opening here in the back where you can see the wire goes in. We're just gonna kind of pull this cover off of there. We can then access the two nuts that hold it in place. They're just plastic. So we're just gonna unscrew these. And this taillight's gonna come out kind of towards the side. Most taillights go straight rearward. This one actually goes mostly towards the side of the vehicle and slightly rearward. So we're gonna use a trim panel tool here as well. Cause this does pop out just like that, and then this kind of just slides off. You can see here's the tab there, where it poked in the side and we've got tabs there where they poke in as well. So now that we've got our assembly off we can just go ahead and twist the bulbs counter-clockwise and those will just slide out of there. Wiring, just pull it out of the little tab there. Now that we've got both the lights out, we'll just set this in the trunk and we'll remove the one on the other side the same way. Now we can take our harness and we're gonna start with the end that has the yellow wire. So you have yellow, red and brown. These wires are the driver's side wiring so they need to be fed up from underneath, towards our taillight assembly here. We're gonna be using some airline tubing as an assistant to help us get this wire run. A metal coat hanger also works really well. Just needs to be something that's flexible, but also stiff enough that you can poke it down to get it to come out below. So we're just poking in the open cavity here on our tail light. And we're just bringing it down until it comes out below. Right there. So now we're just gonna take our harness here. We're gonna take all the wires, kind of just jumble them together. We're gonna put it on the end of the airline tubing where it poked out the bottom, and we're just gonna use some electrical tape to tape our wires to that airline tubing. And then we pull on our airline tubing. It'll pull our wires up. Next we'll need to identify the wires for the signals on our vehicle. I've already identified these. The yellow wire here is our turn signal. The purple wire is the running lights, and the orange wire is the stop signal. So now that we've identified all three of these circuits, we're gonna be hooking those up. So we're gonna take these three. We're gonna cut each one. And then we're gonna strip the ends back on each of these wires. We can start hooking them up. We're gonna go ahead and start with the taillight circuits, which is the brown wires on our harness. That's gonna be the purple wires on our vehicle. If we look at the labels, we can see that this says "Taillight Output." Output means even though it says "To Module" here, that means really towards the light assembly, towards the bulbs or LEDs, whatever you have on that taillight assembly. Input means it's coming, just like it says here, from the vehicle. This is the signal that's gonna tell it to turn the light on. So that's these wires here. This is our vehicle side, and this is the light side, or module is how they put it on the wire harness. So we're just gonna crimp these into place. I'm gonna start with the input side here, from the vehicle with our brown wire going to our purple wire. Let me poke that wire in there and then crimp it down. And then with the output side of our brown wire this is just gonna go right back to the other side of the purple wire. So we're always gonna keep these wire colors kind of matched. If you hook the brown to whatever color you get here you're gonna hook the brown to the same color on the other side Once we've got these connected, we're just gonna move on to our stop and turn signals and get crimped down. So we'll go ahead and do the yellow wires next, which is our turn signals. These are actually gonna hook to the yellow wires on the vehicle. And then lastly, our red wire is gonna connect to the orange wire. All the connectors that come with our harness are heat shrink butt connectors. So we'll use our heat gun to shrink them down. Now we can route the rest of our harness across. So this is just a loom portion of it, not the exposed four wires. We're just taking the other loom that has the green, brown, and red wire, we ran it across just above the bumper beam, we zip tied it to one of the factory wires here towards the middle to keep it from sagging down, and then we use our fish wire trick once again to pull that wire up behind our passenger side taillight assembly. And now over here we made the exact same connections as over there. The colors are gonna be the same. Yellow is still gonna be your turn, orange is still stop, purple is still tail. So you can see that the red on this side still is stop, so it goes to orange. Brown is still tail, so it goes to purple. The only difference is that on this side it's a green wire for the right turn signal, and that's gonna hook to the yellow wire. We can now go ahead and reinstall our taillights. Our bulbs are gonna slide in, pay attention to the notch. There's a small, skinny little notch, and that's our little alignment notch there. You gotta line those up to get these bulbs in. So line those up and then just twist it clockwise to lock it in place. Same thing with this one, it has its own notch. So just look for it and then make sure you line it up. And then we can just re-install the assembly. I am gonna take a couple of the wires here and just poke them up into, there's a small little wire holder right there so I'm just gonna poke some of the wires in there just to help hold them up. And then the assembly after you get your wires poked in, it's just gonna reinsert into the various holes. So just line those up. And then we can reinstall the plastic nuts on the inside. Once we get this side tightened down, we'll do the same over on the other side. We can then re-install the panel, it just pushes back into place here to cover up the exposed nuts Line up the tab there at the top, click it in place. We're now underneath and we're gonna take the ground wire. You should have a single white wire that's just kind of coming out of your harness that has a ring terminal it's pre-attached to it. This is ground. And we're just gonna run this into the bottom of the frame down here. We're gonna use the included self-tapping screw, push it through our ring terminal, and then just run it right up using a 1/4 inch socket. Just make sure it's snug. All right, everything is good there. So at this point now we can route our harness towards the front. You're gonna have a large amount of this four-pole wiring here. And we just take this all the way to the front of the vehicle. I slid it behind the heat shield to stay away from our exhaust because we want to avoid anything excessively hot and anything moving like our steering and suspension components. So we just stay above that heat shield. We bring it all the way forward. You can see it straight up here, where we come out the other side of the heat shield. Once we come out that side of the heat shield, we go towards our fuel tank, and we stay between the fuel tank and this heat shield. So we come out down here, you can see it down the bottom. We go along the bottom side of the fuel tank staying above the heat shield. We continue to stay above the heat shield all the way until it comes out to about this point. We stay under this heat shield all the way forward then from here. And there's just a couple of 10 millimeter nuts. You can take these out if you need to to help poke the wire up in there and you can see it comes out right here at the front of all those heat shields. That'll keep our wire nice and safe and protected. From there we go up into our engine compartment. At this point, I recommend routing it up to the engine compartment so you can attach it to your braking system. If you have a portable system, those often don't need to connect to your diode wiring. So you could can just continue running it along the bottom straight forward. But if you're planning on installing any type of braking system that's not portable then I highly recommend going up first so you can attach it to that system. And here you can see where our wires routed up. We just zip tied it to pre-existing factory wiring along the way to ensure that it stays up and out of harm's way. From there we go down below the breather tube here, where it goes into the throttle body. And then we come out right here, heading underneath the driver's side taillight. From there it just pops out the front and then we head over. And you might notice that we've got the whole fascia off here. That's cause we just got done installing our base plate and this is the perfect opportunity to do the rest of your flat tow components. So I'm gonna get the breaking system and all the diode wiring and all that stuff done while I've got this fascia off. It really made it easy to get this wire up here. And then when you can see all the excess that we've got here, there was a four-pole end on here, it comes with it on there. I cut it off cause it just makes routing the wire easier. And we're gonna be switching it over to a six-pole in the end anyway. Six-poles are the most common connectors for the front of your vehicle for a flat tow setup because it gives you options for additional accessories, such as a charge line, or potentially running monitor lights up to your RV. You do also get with this kit though, a four-pole harness. So if you wanted to leave the four-pole end on here, you could. It is gonna make routing that wire more difficult. You could always reattach it and mount it here at the front cause you do also get a four-pole bracket. But again, we're gonna be omitting the four-pole bracket for a six-pole connector. And you also get a small length of four-pole harness so you could plug into a four-pole here and then also a four-pole in the back of your motor home. But most motor homes have seven ways. So you'd need a bunch of adapters. We're just gonna go ahead and put the best option on there while we're at it. Now, if you left the four-pole end on, your installation would be complete at this point. You'd just need to mount it up to the four-pole mount here at the front, and then test everything out. If you are upgrading to a six-pole, then follow along with us here shortly. I'm gonna finish up getting the fascia and things back on because we're not gonna be able to slide it back on with our larger connector here in the way. Once we get those components back on, I'll show you how to get these four wires attached to a six-pole. So now that we've got our fascia back on, we can go ahead and get our connector attached and mount it up. We're gonna be using a six-way connector from Hopkins, as this is the most common style for flat towing. We're gonna remove the rubber boot from the back. We're gonna slide it over our wiring. Just gonna push that back up in there a little. And then I took each of these wires here and I just cut in between them and I pull them back a bit. You can see, they just kind of peel apart once you cut in between them. And we're gonna strip each one of these ends back now. We can now hook up our six-way connector. We've got those stripped back. We're gonna start by unscrewing the screws in the appropriate locations for our wiring. They are labeled. We're gonna start with this one here labeled GD. GD is the ground connection. So we're just gonna unscrew that. Next we're just gonna go around now. Next is LT for left turn. We're gonna be using that one. That's our yellow wire. Next is RT, that's right turn. That is our green wire. We're gonna be using that as our right turn signal. Next is A, which is for the center. That would be where your charge line would go if you we're installing a charge line kit, but our customers did not install one, so we won't be using that. The next one's labeled S. This is typically used for brakes, or oftentimes if you're installing a braking system, this one's really not used in most cases for flat tow so you can use this as a circuit for running an indicator light into your motor home, but our indicator light's in our vehicle. So next, we're gonna go on to the next one, which is TM, which is for our taillights. We are gonna be using that. That's our brown wire. So now that we've got all those loosened up, we're just gonna go back to the one labeled GD, which is ground, and that's our white wire. We're gonna poke that in there. And then we are gonna tighten down the screw. We'll then just repeat that, working our way around, putting the appropriate wire in the correct slot. And then we're gonna put a generous amount of dielectric on the back of our connector here to help seal it up and prevent any moisture getting in there so we don't have to worry about corrosion. We'll then slide our rubber boot down, put it back into place. And then I like to use some electrical tape to tape up each end. You do also get some wire loom with your kit, which I'll be cutting to cover up this wire just to give it a more pleasing look. We can then mount our connector up. Our base plate does have an attachment point on it to mount your connector. If your base plate didn't, if you're using a different manufacturer's base plate, the connector that we've got here from Hopkins does come with its own bracket so you could mount that up. Those are just gonna slide in, and this is the hardware that came with our base plate. So we're just gonna run that down. If you're using a Blue Ox base plate like we are, you'll use an eight millimeter socket to tighten these down. Now that we've got it all hooked up, we can go ahead and plug it into our motor home to test it out. We're gonna be using a test box here in the shop. And you just want to operate all your lighting signals and verify that they're mimicked at the back of your vehicle. So you can see here, we've got our left turn signal, right turn signal, tail lamps, and brake lamps. With all of our signals working properly, We're ready to hook up to our motor home, put it into flat tone at the road. And that completes our installation of Curt's Diode Wiring Harness on our 2017 Ford Focus..


Info for this part was:

Employee Jeff D
Installed by:
Jeff D
Employee Jacob T
Video Edited:
Jacob T
Employee Dustin K
Video Edited:
Dustin K
Employee David F
Test Fit:
David F
Employee Bradley B
Test Fit:
Bradley B

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