Trailer Wiring Harness Installation - 2017 Mazda 3

content loading

Customers compare 118405 to these similar products




Products Featured in this Video



How to Install a Trailer Wiring Harness on a 2017 Mazda 3


Speaker 1: Today on our 2017 Mazda3, you're going to be taking a look at, and I'm going to show you how to install, the Tekonsha T1 vehicle wiring harness with 4 Pole flag trailer connector, part number 118405. This is what our wiring looks like when it's installed. This is going to give us the proper lighting functions to safely tow our trailer down the road. It's going to give us both turn signals, or running lights, brake lights, and our ground. It's also going come with a nice dust cap to cover your connections, to reduce any moisture, dirt, and debris from getting in and ruining into the connections there. As far as the installation goes, it is a fairly simple installation.

It's going to hook directly to your taillight wiring, or your factory wiring on your vehicle, and then to your taillights. You're going to have a power wire that's going to run to the battery in the front of the vehicle.You're also going to have a fuse that's going to fuse that link. What I really like about this wiring is it's going to have a converter box, and what's the converter box does, is it's going to prevent any back feed from getting to your factory wiring in your vehicle. That means is if your trailer wiring has a short in it, the converter box is going to stop that short from getting into your factory wiring and ruining that wiring. The good thing about the power wire being right up to your battery is it's not drawing any power from your taillights, if your trailer happens to have a few extra lights on it.Now that we've gone over some of the features, let me show you just how easy it is to get installed.

First thing we need to do is this panel that runs right along the back here, we're going to take either a pick, or you can use a small screwdriver, and you're going to have little fasteners running along the front side of it. We need to pop those off just like that. You're just going to pry out the center. We just need to get it out enough. You'll see three nuts.

There's one here, one on top, and one on the other side. We need to remove that to remove our tail light. Take a 10 millimeter socket. We'll remove our nut. We'll go ahead and unplug our wiring.

We're going to pull our taillight towards the back. We may need to use a little plastic trim panel tool. We'll just work the taillight out. We may want to pull back on our taillight. Set our taillight aside. Now we're going to repeat the same thing on the passenger side.Next, I'm going to either use a wire hanger, airline tube. Wat I like to do is take a string, put a nut or a bolt on it, something that has a little bit of weight. I'm going to drop it right down the hole and it's going to come right out the bottom. I'm going to take the end of my wire that needs to connect to this. I should make a loop like this, and this side's going to have two. I'll just feed one end like this, pack it down, and pull it up like that. Now I'm going to take the ends of my two plugs, and and I'm just going to match them up. Then we can plug in the other two ends back into our taillight, and then reinstall our taillight. Install our taillight in place, and then put our three nuts on on the inside. Next we're going to mount our converter box.This isn't really flat right in here, but right on this back side it's flat, but because it's open to the elements, we're going to need to clean it off. Let's use a rag, paper towel, with some rubbing alcohol. We'll make sure that area's cleaned good. I'm going to take our double-sided tape that comes in our kit, in our converter box. Make sure your press it into place. Remove the other side. Take this, then we're going to push it into place. Next we're going to take the red wire coming off of our converter box. We have butt connectors that come in our kit, however, they're not waterproof, so what I'm going to do is I'm going to change them out for waterproof, or heat shrink butt connectors. Go ahead and take one. Put it on the end of our red wire. Crimp it down. Now we're going to take the black wire that comes in our kit. You need to strip one end.We're going to add this to the other side, crimp it down. Then we'll take a heat source and shrink up our butt connector. Pour in an amount of groundwater. When you use a self-tapping screw, 1/4" socket, you want to make sure it's mounted to metal. I'm going to go right up here on the bottom panel of the body. Next, we're going to take our green wire. It's going to our passenger taillight, and our 4 pole wire, and you're going to have little plastic brackets that hold the bottom of your fascia in place. So we need to go behind our hitch. We're going to leave our 4 pole wire in here, and take our green wire. inaudible 00:05:19 brought it over to our passenger side. We're going to do the same thing over here. Just going to put a little loop like that in our wire.Stick it through the nut, just like that. I'm going to take some zip ties, and I'm just going to zip tie around my wiring up here in this bracket in my fascia just to kind of hold my wiring in place. Now we're just going to match our plug to our wire, whichever one it goes to. Then we can reinstall our taillight. Once you have your passenger side taillight in place, you can go ahead and reinstall your interior panels. Next I'm going to run my power wire to the front of the vehicle. Let me get that done real quick, and I'll show you how I did it. My power wire. You want to make sure you stay away from anything hot or moving. Find some existing wiring. Zip tied it right here. Went over top of this brace. Zip tied it right here to this hard line. Went over the top. All's I did was ran it right underneath this whole panel that runs right up to the front of the vehicle. I did the same thing here. Wrapped my string with my nut on it, and I'll take my wire, that little nut like that, then we'll roll it tight and pull it up.I will say double check to make sure your wire isn't that hung up on anything down there before you do any cutting. I routed my wire right around the back of the battery box to my positive side. So what I'm going to do, go ahead and cut my wire out there, and shook it back. Now we'll add our heat shrink butt connector. Put it in place, and you're going to take your fuse holder, cut the wire in half. We're going to strip back both sides. We're going to add a ring terminal on one, and end the other end to our butt connector. Now we'll take our heat source and shrink that butt connector. Next, take a 12 millimeter socket. You're going to remove this nut right here on our positive side of our battery. We're going to go ahead and add our ring terminal. You want to make sure that the fuse is not in the holder when you make this connection. Put your nut back in place.Once your connection is made, you can go ahead and add your fuse. Our customer chose to use two brackets to give our 4 pole a more permanent mounting location. You can mount it up like this, and you get on down like this if you want. I'm going to mount it like this. It's going to come with a hose clamp. Get it and tighten it now. I'll get it tight. We can cut off our excess. We're going to mount our 4 pole bracket. We can mount it either down like this or up like this. Since my wire's coming down behind my fascia, I want to put it like this, kind of hide my wire there. Tighten it in place. Add in our 4 hole. Now we can test everything out to make sure everything's working properly. Brake lights, left turn, right turn, running lights. That'll do it for our look at, and installation, on the Tekonsha T1 vehicle wiring harness with 4 Pole flag trailer connector, part number 118405 on our 2017 Mazda3.


Questions and Comments about this Video

Info for this part was:

Test Fit:
Joe V
Test Fit:
Alan C
Test Fit:
Randy B
Test Fit:
Shane H
Test Fit:
Ryan G
Video Edited:
Zack K
Video Edited:
Joshua S
Video Edited:
Jacob T
Video Edited:
Dustin K
Video Edited:
Sue W
Video Edited:
Chris R
Video by:
Andrew K
Video by:
Kathleen M
Video by:
Jonathan Y
Installed by:
Cole B

At etrailer.com we provide the best information available about the products we sell. We take the quality of our information seriously so that you can get the right part the first time.