Tekonsha T-One Vehicle Wiring Harness Installation - 2018 GMC Terrain

content loading

Customers compare 118285 to these similar products




Products Featured in this Video



How to Install the Tekonsha T-One Vehicle Wiring Harness on a 2018 GMC Terrain


Today in our 2018 GMC Terrain we're gonna be installing Tekonsha's T1 vehicle wiring harness, part number 118285. This harness is gonna plug into your trailer to provide it with all the necessary lighting. You simply plug in your four pole connector from your vehicle to your trailer, and it'll now provide all the necessary lighting, which includes your left turn signal, right turn signal, tail lamps and break lamps.Since this harness plugs right into your factory tow package, it acts as an adapter allowing you to get that four pole connection out at the back of your vehicle. Since you're using your factory tow package connector, all the necessary circuit protection is built into your vehicle for your towing circuits. This way, if you have a fault on your trailer, instead of it affecting any of the turn signals that you may have at the back of your vehicle, it will open the fuses for your tow package in your vehicle, which won't affect the lighting on the back of the vehicle.There's an included dust cap to keep out any dirt and debris, to ensure that you have a long lasting four pole connection. Additionally you can use this dust cap to keep the harness up and out of the way when not in use, by hooking it onto your hitches safety chain loop.Included in your box you'll receive your factory tow harness adapter connector as well as a bag with some zip ties and relays.

The relays come included in case your vehicle may have the factory tow harness connector, but does not have the relays installed in the fuse box. Most vehicles do, however, that come with a tow package, have the relays already installed. Your harness is gonna measure about 4 1/2 fee long, and each output for your left turn, right turn, and tail lamps, is gonna have a maximum output of 7 1/2 amps. This is a pretty big amperage draw, so you can run quite a few lights on your trailer.If you don't have a factory tow package Tekonsha still has an answer for your vehicle. This is gonna plug directly into your tail lights, and wire up similarly.

You can pick this up here at etrailer.com with part number 118764. However, if you do have a factory tow package, I highly recommend this harness, 'cause it's gonna plug in and install in minutes unlike the lengthier installation you would need for this one.We'll start our installation underneath the vehicle behind the bumper here kind of on the center a little bit towards the driver's side and locate our factory tow plug connector. You'll locate your connector here. You'll know it's the right connector because it will have a dummy plug in it where there's no wires coming out of that plug. The red tab will need to be released.

You just pull outward to release that tab, that's our locking tab. Once it's unlocked you can then press in on the release button here and pull the dummy plug off.Here's a better look at our dummy plug. This is what you'll be looking for. That would be the lock position on how you would find it. Simple pull that back to unlock it, and the release tab is here.

Now, all we do is simply plug in our new harness. Once you've got it connected, we can take your wiring and you can route it up so it's out of the way. We're just gonna be putting ours, and connecting it to our hitch her. We're just taking that wiring, there's a hole in the bottom of your bumper right here, we're just gonna run a zip tie through that hole. You'll get a few zip ties included with your harness. We're just gonna wrap that around and just zip tie those behind the bumper here.Now we can plug it in and test everything out. You can either plug it into your trailer, or you could purchase a tester like the one we have here at etrailer.com. You wanna make sure that you have your left turn signal, right turn signal, tail lamps, and break lamps. With everything working properly we're ready to hit the road. That completes our installation of Tekonsha's T1 vehicle wiring harness on our 2018 GMC Terrain.


Questions and Comments about this Video

Info for this part was:

Employee Joshua S
Video by:
Joshua S
Employee Jonathan Y
Video by:
Jonathan Y
Employee David F
Video by:
David F
Employee Aidan B
Video by:
Aidan B
Employee Jacob T
Video Edited:
Jacob T
Employee Chris R
Video Edited:
Chris R
Employee Cole B
Installed by:
Cole B
Employee Robert C
Test Fit:
Robert C
Employee Ryan G
Test Fit:
Ryan G

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.