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Trailer Wiring Harness Installation - 2017 Subaru Forester

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How to Install a Trailer Wiring Harness on a 2017 Subaru Forester


Today on our 2017 Subaru Forester we're going to be taking a look at and installing the CURT T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector, part number C56040. Here's what this wiring is going to look like once it's installed on the vehicle. As you can see, we've got access to it from underneath the cargo area here. That's where it's stored away when not in use. In order to do that, you can take it and simply bundle it up in here, right down in there so it's out of your way and you've got full use of your cargo area without needing to worry about damaging that wiring. When you're ready to use it, you just pull it back out and then you can close the trunk. You want to make sure to avoid the latch area so that it doesn't pinch the wiring.

Then you've got easy access to plug it into your 4-pole trailer. I'll go ahead and put it back in the storage area, but what's really nice about this is that it's a nice plug and play system, so it just simply plugs into the factory wiring on the vehicle and you don't need to worry about tapping in with T-connectors behind the tail lights. It also features a module box that helps to protect your vehicle's electrical system from any backfeeding from a short in the trailer. Overall, this wiring harness is nice and easy to install, but it's also very convenient and it's going to do a great job of making sure that you've got power to your trailer. Now let's show you how to install this wiring. First thing we'll need to do is we're going to have to take everything out from back here in order to gain access underneath.

Then over here there's 2 little push pins that tie this section down so I'm going to use a trim panel tool, but if you don't have one you can just use a flat head screwdriver. You just need to get under here and pop them out, and then you can remove this. Then, once we're over here, there's a 10 millimeter bolt that's under this, and then a screw in this hook. We'll need to take those out in order to be able to remove the side paneling. In order to get to that 10 millimeter bolt, you need to lower this hook. Then you just take a flat head screwdriver, get in there, pry it a little bit, and it'll pop out because it's just got 2 little retaining tabs on it.

Then you can remove that 10 millimeter bolt and take the cargo hook and set it aside. Then, inside this little cargo hook, got a Phillips head screw you need to loosen up. Once you've got the screw out of there, you need to take this and twist it to the left and it'll come out. The last thing we need to do before we can pull the side panel out is we need to take this threshold and get it out of the way. In order to do that, you just grab it and gently pull upwards until the push pins that hold it down are released. Then you can take that and set it aside.

Now, there's a few push pins that hold in this side panel so you just gently take the bottom and begin to pry outwards. It should pop right off. You can see those push pins there. Then, right back here we've got this blue tape that's holding the connector for our wiring harness. We'll pull our side panel back here and make sure that our wiring is routed to where it'll be coming out underneath that panel when we put it all back together. Then, here on our connector we can make the connection with our wiring harness. You want to make sure it clicks so that you know it's secure. Then we'll find a good place to mount our module box here. I'm going to mount it right along the inside here on that flat spot, so I'm going to take a little bit of rubbing alcohol and just clean that area to make sure that it's going to adhere well with the double sided sticky tape. Then, on the back of the box I'll take the double sided sticky tape, put it on there, then I'll be able to mount it right there where I just cleaned off. That'll be a nice, secure location for it. Once I'm done with that, I need to find a good spot to ground it. Where I'm going to do that is just right up over here to the metal of the body. Wherever you decide to put your ground, you want to make sure that there's nothing behind there like wiring or anything that might get damaged. I'll take the self-tapping screw supplied in the kit, then just run it through here. Then you want to make sure it's down nice and tight. Then, once we've got that in place we can take some of this wiring, and I'm just going to put a zip tie around it just to help secure it so it's not all over the place, and then I'll clip off the excess on that zip tie. While I've got it here, I'll go ahead and install the fuse into the fuse holder. Now, we're ready to begin reinstalling our side panel. Now that we've got our side panel reinstalled, we can reinstall our threshold and our cargo flooring. You just want to make sure that this weather stripping is back up over the edge of the threshold so that it can function properly. Now that we've got it all hooked up and put back together, let's test it to make sure that everything's working properly. I'm going to use part number I26 in order to do that. First, we'll check our tail lights, left turn signal, right turn signal, and brake lights. With everything working properly, we're ready to hit the road. That's going to complete our look and install of the CURT T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector, part number C56040, on our 2017 Subaru Forester.


Questions and Comments about this Video

Don P.

where can I get that part no.126. looks like a lot of help to me.

Etrailer Expert
Reply from Jon G.

Are you talking about the trim removal tool that we were using? That would be part # ALL648544 . If you were talking about something else just let me know what the minute mark is in the vide and I can see if I can find it.

Reply from Don P.

@JonG No. it that little plug in tester to see if everything is wired correctly.

Etrailer Expert
Reply from Jon G.

@DonP Got it, that would be part # I26 .

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