Curt Vehicle Wiring Harness Installation - 2020 GMC Terrain

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How to Install the Curt Vehicle Wiring Harness on a 2020 GMC Terrain


Hey everybody. It's Rob here at etrailer.com. Today, we're going to be taking a look at the Curt T-connector vehicle wiring harness, on our 2020 GMC terrain. Now our Curt wiring harness is going to provide us with a four-pole flat trailer connector. So we're going to have all the required lights to get down the road safely when we're pulling a trailer like our tail lights, our turn signals and our brake lights, but trailer, wiring's not only going to be good for a trailer. It comes in handy for a lot of different accessories.

Maybe you have a step back here that has a light on it, or possibly a cargo carrier with a light kit. It's a lot easier to plug those things into a four-pole connector. Cause most of them are going to be plugging into your trailer wiring. It's a lot easier to plug that in there and then just try to hard wire it in.And that's the other really nice thing about our wiring. There's no cutting or splicing involved.

It's simply just going to plug into the factory tow package and provide us with that four pole connector out here by our receiver tube. One thing to keep in mind is, is our wiring is designed to stay on the outside of the vehicle all the time until we're really ready to use it, which is nice because it's going to be right here by the hitch. So we won't have to worry about dropping any wires out of the hatch. Now they do give you a dust cover so you can use it to attach it to your hitch like I did here against the safety chain loop and that'll prevent the excess wire from dragging to the ground. But I always recommend using a mounting bracket because one it'll take up some of the excess slack and it just has a cleaner look on the back of your terrain.Now here in each trailer, we do get a lot of questions about the terrain and the factory tow package and whether it has or not.

Now, this is only one end of our wiring. It's going to be on the outside. However, there are some relays that may need to be put in. The relays are going to be in the cargo area, in the hatch here. And if we come in to the inside, we can see on the driver's side panel, we'll have this little notch right here.

And if you kind of grab it with your fingers, bend it a little bit and we'll get that panel to pop out.And then it'll expose the fuse box and the relays inside. Now the part we need to pay attention to is this top section where we'd have, you can see there would be one, two relays, and then we do have one in the number three spot. So the easiest way to tell if you have the tow package is if you have a relay in number three, you have the tow package. If you do not have a relay in number three, you'll need to have the terminals inside of number three and number one. But as you can see, I can take my relay and I can put it into the number one spot. But as you can see, there's no terminals in there, but we have the factory one in the number three spot. If you don't have the metal terminals or contacts or relays in place, you will need to get the wiring that's made for the non tow package terrain.Now that you know how to check the inside of it. Another thing you're going to need to have is the wiring on the outside of the vehicle, to where the harness that you're going to be putting in is going to plug into. It's a super simple process, you just unplug the cap that's on there and plug in the new wiring, but it can be a little bit hard to see cause it is behind the driver's side rear fascia here, but we'll make sure you knew exactly where it is and how to get it plugged in. In fact, let's go ahead and do it together now.To begin our installation, we want to come to the back of our terrain and we're going to move towards the driver's side pretty much right at the end of the muffler here. And our factory tow package plug is just going to be just behind the rear fascia, but it is going to be a little bit high up.Let's see, you're going to be looking for a plug. I actually pulled mine down from the clip. You're going to have a plug connected to the end of it. Just kind of keeping all the dirt and debris out. There is a small locking tab on there. I'm going to slide it away from the wiring and a little squeeze on the center tab to pull it out. Here's what the plug looks like, and here's that red locking tab. We want to make sure you pull that away and that'll allow you to press down on the center right here and disconnect it. So we can grab our harness now, and you'll notice that the plugs are going to match exactly our new harness we'll have the same end as the W plug. So we're just to plug it in. Now our harness does have that locking tab.So once we plug it in, we want to hear that click and then make sure we click over the red locking tab. So it's nice and secure, audible click, pushing the locking tab. And then I like to give it a quick tug to make sure that it's nice and secure, but all we have left to do now is tie up the excess wire. And I like to go as high as I can to keep it away from the muffler and everything else. You just want to make sure you leave yourself enough room and route your four-pole connector towards the opening of the receiver tube. While sever installation is going to be testing our wiring and making sure that all the circuits are working properly. So I went ahead and plugged in my four, went ahead and plugged in my four pole tester. And you can see when I turn on my headlights, the taillight function is working, as well as the left turn signal, a right turn signal, and our brakes. All we have left to do now is hook up to our trailer and hit the road.


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Info for this part was:

Employee Joshua S
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Joshua S
Employee Dustin K
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Dustin K
Employee Aidan B
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Employee Jacob T
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Jacob T
Employee Chris R
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Employee Cole B
Installed by:
Cole B
Employee David F
Installed by:
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Employee Brent H
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Brent H
Employee Robert C
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Robert C
Employee Conner L
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Conner L
Employee Ryan G
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