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Trailer Wiring Harness Installation - 2001 Toyota Tundra

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How to Install a Trailer Wiring Harness on a 2001 Toyota Tundra

Today on our 2001 Toy0ta Tundra, we'll be installing the Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector, part number C55378. We'll begin here underneath the rear of the vehicle, over here on the drivers side. You'll see that there's a large gray plug right here that actually has an end cap in it. To unplug this, we'll simply push in on the locking tab and gently pull downward. This is the wiring that we'll be tying in the new Curt T-Connector wiring harness to. Now for the box and the 4-flat end of the wiring harness, we're going to route it up here through the frame. This will allow us to protect the box, as well as give us a good flat area to secure the box using the 2-sided tape. We'll go ahead and use a little bit of rubbing alcohol to clean the surface first, before we attach the 2-sided tape to the box, and then attach the box to the frame of the vehicle. We'll go ahead and plug in our connection from the new wiring harness to the factory wiring harness, making sure that we hear the locking tab click into place. We'll go ahead and use a few zip-ties to secure up any excess wiring. Now for the 4-flat, we'll route it down here to the center of the hitch area. We'll then take the cover for the 4-flat, put it on the end of the 4-flat, and then loop it through the safety chain hole on the hitch. Once that goes through, we'll take the end cap and put it back over the end of our 4-flat.

This will keep any dirt and debris out of the 4-flat when not in use, as well as securing it to the hitch. Now we need to move up to underneath the hood where we'll take the other piece of wiring harness. The one that has a fuse holder in it will need to be tied in with the battery. We're going to go ahead and loosen up the bracket that holds the battery in place so we can slide it over enough to give us a little more working room to gain access to the factory plug. Again, this plug has a cap built into it already to protect it from dirt and debris. We'll simply push in on the locking tab and remove the dust cap. We'll then take the end of our new wiring harness and simply plug it into it, again, making sure that the locking tab clicks into place so that the connection is secure. We'll then need to route the other end with the ring terminal up to the positive side of the battery. We'll go ahead and loosen up the nut on the positive side of the battery and add the ring terminal on the wiring harness in-line.

We'll then tighten the nut back down. Now that that's done, we can go ahead and put our battery clamp back down, holding the battery back in place. Next we'll need to install the 10 amp fuse that comes with the kit in the fuse holder. We'll then put the cap on the fuse holder. We'll also use a few zip-ties to help secure any excess wiring up here. All that's left to do is to to run through and make sure that our new 4-flat wiring is working properly,so we'll take our test light here at the rear of the vehicle. We'll take the ground on the test light and touch the open prong on the 4-flat, which is the white wire, and we'll have someone run through the light functions. We'll touch the brown wire for the running lights, the yellow wire for the left turn, the green wire for the right turn, and the yellow or the green wire for the brake signal. As you can see here, everything is working just fine. With that, that will conclude our installation of the Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector, part number C55378, on our 2001 Toy0ta Tundra.


Info for this part was:

Employee Joe V
Test Fit:
Joe V
Employee Shane T
Test Fit:
Shane T
Employee Zack K
Video by:
Zack K
Employee Alan C
Video by:
Alan C
Employee Jeff D
Video Edited:
Jeff D
Employee Jacob T
Video Edited:
Jacob T
Employee Dustin K
Video Edited:
Dustin K

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