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Trailer Wiring Harness Installation - 2009 GMC Acadia

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How to Install a Trailer Wiring Harness on a 2009 GMC Acadia

Today on this 2009 GMC Acadia we are going to be installing part number 118451 from Tow Ready. We are at the rear of the vehicle now and we are going to be removing the driver side and passenger side tail lights. We are on the driver side right now. We are going to pop these plastic caps out that are protecting our screws so pop those off and we will have lanyard that is holding them in position. We are going to remove the bolts that are holding in our tail light. It is going to be the same on the passenger side as well. Then we are just going to pull out our tail light assembly and disconnect it. Take this tab here and pull it back and it will pop out. We are going to set the tail light aside and we are going to remove the passenger side tail light as well. 00:46

We are still on the driver side. We are going to take the 4-pole connector and the green wire with the white connectors on the end of it and we are going to it straight down through the bumper and the sheet metal and it is going to fall out the bottom. We are going to run that underneath the vehicle. As you can see we are going to leave the yellow, brown, and ground outside of the vehicle because we are going to be plugging into the driver side. First we are going to take our ground and attach it to our sheet metal here. We are going to take the male end of our stock tail light harness and plug it into our after market harness for our trailer into the female end until you hear the snap. We are going to route the wires back down in here. Then we are going to reinstall our driver side tail light because we are finished on the driver side of the vehicle. 01:34

We are at the underside of the vehicle now. We are going to reach up where our fender is at and pull down the wires that we pushed through. Now we are going to run our wires across. We are going to start by just tucking them in between the bumper and the bumper support up here. Then we are going to run it through the support here for our bumper. We are just going to run the wire over the top of the hitch and then over the bumper plastic support here and take our 4-pole and attach it there. Then what we did is took some flexible wire and ran it down through the top of our passenger tail light bumper all the way out the bottom. We are just going to attach to our harness and just pull it up. We are going to take the male and female end and plug them in. We are going to take the harness and plug it back in to our tail lights and then we will be done. Just hide the wires a little better and then we will just take our tail light and put it back in position. This will conclude the install for part number 118451 on this 2009 GMC Acadia.

Daniel O.


Hi team I have a 2009 GMC Acadia and I would like to buy the trailer harness that you showed in your video, let me know about it to buy from you guys. Thanks Daniel Ortiz

Les D.


@DanielO It is super easy to order. I placed a link to the harness below. Just go to that page and click the "Add to Cart" button. Then click the cart button at the top of the page and check out to have the part shipped right away.

Info for this part was:

Employee Zack K
Video Edited:
Zack K
Employee Joshua S
Video Edited:
Joshua S
Employee Chris R
Video Edited:
Chris R
Employee Patrick B
Test Fit:
Patrick B
Employee Cole B
Installed by:
Cole B

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