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Trailer Wiring Harness Installation - 2003 Chevrolet Express Van

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How to Install a Wiring Harness for a Trailer on a 2003 Chevrolet Express Van

Today on this 2003 Chevrolet Express Van we are going to install part number 31345 from Hopkins. This wiring harness plugs into the existing factory harness and the connection points are located inside the vehicle, below both tail lights. The first thing we are going to do is get inside the vehicle and we will remove some panels to get to our wire harness. :19

We will start over on the driver side here, because we need to get behind this panel here. We will use our trim panel tool to get to our fasteners. Just kind of push on the metal part and pry it out. The next thing I am going to do is remove this panel here to give us a little more working room. When you open up the panels you will see these two connection points, they look like the ones on the T-connector, however these are the wrong ones. That is why I removed this upper panel, so you can see where this second set of connectors is. You can verify it because it goes into the tail light itself. That is the connection you need. 1:01

We have the driver side cleared out, so lets go to the passenger side and do the same thing. Lets go ahead and start our install with the driver side here. You want to push down on this point right here and pull apart the connectors. Sometimes it is helpful to use a small screwdriver to push the pin in. Our connection point will plug in together, just like the factory did, and we will just tuck that behind the tail light. Next, we will take our white ground wire and tack that to the ground point right here. You will notice the grounding screw is a little big for the ring terminal itself, so we ended up taking a drill bit to it and making the hole bigger. Take our ground screw, install it, and we will be good with that. We will leave our box out, the next thing we are going to do is run our green wire that goes to the passenger side and tuck it in behind here, through this hole, and have it come back out through here. The next thing we are going to do is hide our convertor box, we are going to run that through here also. The red wire is a little bit on the short side, so we are going to leave that hanging out up top here, we will make that connection a little later. Now we are going to take our green wire that goes to the passenger side and take it and run it underneath the plastic here and just tuck it underneath all the way across. Try to keep it in as straight as a line as possible because there is just barely enough wire here to make the journey across. Lets go ahead and put our connection together. At this point you can secure the wires that you see fit, a lot of it is going to get covered up anyway. A zip tie right here is all we need. 2:36

For the passenger side we are pretty much done, so we can reassemble that part. We have one decision to make here. First off, with the four pole wiring harness itself, we can do this two ways. One, you can leave it in the inside when we are not using it, or what we are going to do, run it outside and eventually we are going to put a different type of connector on it. To run it outside, we are going to pull away this door seal and make a small cut in the sheet metal so we have enough room to wrap this around the edge and go back outside. It will be a little short for trailering purposes, but from this point on we can add an extension or a different type of connector on here. The next thing we are going to deal with is our red wire, this is our red extension wire that came with the kit. What is going to happen with this is we are going to run this from our connection right here and take this and run it up to the battery on the vehicle. Crimp it and stick it down inside. We have a bunch of loose wires here, what we are going to do is take some tape and bundle them together to make them a little more manageable as they go out the vehicle. Lets take our remaining red wire and put that down behind the bumper and let it fall to the ground, as well as our four pole. We have our wires run outside, we will go ahead and reinstall our interior panels now. We have got our wires here, now we are going to take our four pole harness and route it over the frame, as close as we can to the hitch. As you can see, when we run it outside we have hardly any wire left over, so it is a good idea to use an extension on top of here. We are going to leave that alone for now, and we will go ahead and take care of our red wire. We will run that along the frame and up to the battery. We ran our wire to the front of the vehicle, we basically stayed near the frame of the vehicle, staying away from suspension components and anything else that is moving. Pull it through existing wire harnesses and fasteners to help take up the slack and hold it in place. 4:32

It also turns out that our wire is just a little too short for this van, since it is an extended body, so we are going to take some 10 gauge wire and extend it up from the bottom of the engine compartment up top to our battery. We have our wire pulled up. The main thing we did was stay away from anything that was moving or gets hot, like the steering linkage and the exhaust. Basically, stay away as close as you can to the firewall, and that usually works out pretty good. You can thread it through here and have this clip do double duty. We are going to zip tie it right here, go through this clip here and over to our battery. We will take our wire and see how much we need to meet our battery, it looks like this will be just fine, so we will cut off our excess and install our fuse holder between our wire and the battery. We will crimp that in place. Before we make our connection to the battery, it is a good idea to disconnect the ground first so we do not short out the positive side of the battery. When we connect our positive side up, whats going to happen is you are going to have to attach this to the bolt and bolt it back into place on the battery. It can be done, you have to trim some of this off, but it is possible to use a battery lead that replaces that. It will replace the bolt inside there with something you can actually attach your power wire to. That is part number DW05416. Now take your tap and push it right back in. Then go ahead and bolt this back in to place. Again, we are going to leave our ground off. We will take off this nut here and have easy access to our power supply. Now we can hook up our fuse holder and tighten it back down. At this point we can reattach our ground. Make sure our fuse is good in our fuse holder. Our wire harness is installed, next we are going to do is check the four pole with a light tester to ensure a proper operation. With that, that will finish our install of part number 31345 from Hopkins.

Info for this part was:

Employee Joe V
Test Fit:
Joe V
Employee Randy B
Test Fit:
Randy B
Employee Brent H
Test Fit:
Brent H
Employee Shane H
Test Fit:
Shane H
Employee David F
Test Fit:
David F
Employee Zack K
Video Edited:
Zack K
Employee Joshua S
Video Edited:
Joshua S
Employee Jacob T
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Jacob T
Employee Chris R
Video Edited:
Chris R
Employee Andrew K
Video by:
Andrew K
Employee Kathleen M
Video by:
Kathleen M
Employee Cole B
Installed by:
Cole B

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