Trailer Lights do not Work with the Tow Ready T-One Harness # 118451 on a 2010 GMC Acadia

Question:

I have installed #118451 as directed and my trailer lights would not work. I double checked the install and ensured a good ground. I checked the fuse block and found it did not have a fuse or relays. Looks like there are incomplete legs on the fuse and relay spaces. Came back to the website and found where one of the tech experts said this kit would work without upgrading the fuse block. Just trying to confirm this before I go further. Should this kit work off the tail light circuit alone? Thanks for helping me with this.

asked by: Ted H

Expert Reply:

The Tow Ready T-One Wiring Harness, # 118451, does not require any additional fuses or relays. As you said, this harness provides power to the trailer lights from the vehicles tail light circuits. The only time you would need to install a fuse is if one of the taillight fuses were blown on the vehicle. This would mean your taillights, turn signals or brake lights were not working on your Acadia.

If you are positive that you have a good ground and the T connectors are installed correctly on the taillight assemblies, the harness should work as described. To ensure the harness is working properly, I recommend using a circuit tester, like part # PTW2993 if you do not have one, to test the pins at the connector. I have attached a video of my coworker demonstrating how to test a 4-way flat trailer connector on a vehicle.

If all of the functions work at the 4-way connector, the issue may be on the trailer. I recommend inspecting the trailer end connector for dirt and corrosion. I also recommend inspecting all of the ground connections and wires for additional corrosion or damaged wire insulation. Damaged wires can create a short which prevents power from reaching the taillights.

If your Acadia has LED lights and your trailer has incandescent lights, it may be possible that the taillight circuits on the Acadia do not have enough power to power the trailer lights. LED lights only require a fraction of the power that is required by incandescent lights. To resolve, this, a powered converter must be installed, like part # 119250KIT. This harness will draw power directly from your vehicles battery to power the trailer lights.

To install this harness, you can cut off the 4-way connector on your harness and splice this harness to the wires from your current harness color for color. The red wire will be grounded with the white wire and the black wire will run to the positive post on your car battery. This harness will also protect your vehicles electrical systems from shorts on the trailer.