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Trailer Wiring Harness Installation - 1999 Jeep Wrangler

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How to Install a Trailer Wiring Harness on a 1999 Jeep Wrangler

Today on this 1999 Jeep Wrangler we are going to install part number 118409 from Tow Ready. This is their T-One wire harness. Right now we are looking at the driver side of the vehicle and our connection points are going to be behind the body work right here so pull away the plastic trim panel right here to get access to the wiring. There is a little plastic rivet right here that we have to remove. Now you have to follow the wire harness up and there will be a connection point where you unplug. This one happened to have a bunch of tape wrapped around it so uncover the tape to get to the connection harness. It is kind of hard to see but there is a little latch on the top. Push down on it and it should pop apart. 00:39

Now we will install the T-One using the side with the yellow and that is for the left turn. Plug them together until it snaps. Then do the other side. Now you can reassemble the plastic trim piece. Now we will take the 4-pole end of the harness and we are going to route it behind the bumper and we will take the T-One connector, the green wire, and pass it through too and run that over to the other side. Again we will get behind the plastic panel and repeat the same process. Now we will take our white wire with the loop and that is going to be the ground terminal and we will ground that straight to the frame. Take a self tapping screw and run that straight to the frame. We will take the 4-pole and tie it off right here at the chain loop and leave it sit. Then we will take up the rest of the slack in the wire harness. There is a hole behind the bumper and we will use a zip tie to tie off the passenger side wires to hold it in place. We will go to the driver side and do the same thing. With that, that will finish it for part number 118409 from Tow Ready.

Ron P.


I did not get how it hooks up the the rv. How you ran the wire. etc.

Etrailer Expert

Rachael H.


This wiring harness is intended to be installed to use the Jeep to tow a trailer, not to allow the Jeep to be flat towed. That kind of wiring is called tow bar wiring, I have included a help article regarding that type of wiring. You can enter your year make and model vehicle in our fit guide and then choose tow bar wiring and you will see the options for installing a flat tow wiring set up for your vehicle.

Info for this part was:

Employee Joe V
Test Fit:
Joe V
Employee Zack K
Video Edited:
Zack K
Employee Joshua S
Video Edited:
Joshua S
Employee Jacob T
Video Edited:
Jacob T
Employee Jeff D
Installed by:
Jeff D

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