Hopkins Endurance 7-Way Trailer Wiring Installation - 2015 GMC Sierra 3500

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How to Install the Hopkins Endurance 7-Way Trailer Wiring on a 2015 GMC Sierra 3500

Today our 2015 GMC Sierra 3500, we'll be taking a look at and installing the Hopkins Endurance Quick Install 7-way Trailer Connector, part number HM47210. If your vehicle is equipped with the fifth-wheel towing package, it will probably have a pigtail that looks similar to this. This is a factory pigtail, and we're going to be using our universal pigtail to hook up to it. We aren't going to have a long enough ground to connect that to the frame, so we'll go ahead and connect that to the ground that's provided in the factory hookup. We'll go ahead and trim off the ground to the same length as the other wires and then we'll strip back our wires. The first 2 wires we're going to strip back is going to be that ground and the power. We'll first hook up the ground wire and then we'll hook up the power wire, that way we don't have to worry about disconnecting the battery. We will not go ahead and splice our wires together with the assistance of the DECA heat-shrink butt connectors, part number DW05745-10.

We'll take our DECA heat-shrink butt connector, we'll connect that onto the end of our ground wire, we'll crimp it down, and then we'll go ahead and cut back our factory trailer connector to expose our wires. We'll go ahead and cut this back. We'll use a sharp knife or carpenter's knife to do so. We're going to peel it back just a little bit so we have room to work, and then, we'll go ahead and cut it off. Next, we'll go ahead and cut off the ground wire and we'll strip that back.

Make sure you give it a good twist, press it in, and we'll crimp it. Next, we'll go over and do our power wire making sure that all the other wires stay clear so we don't ground anything out, red to red. Now, we'll go ahead and cut off the rest of these and make our connections. If your factory harness does have a factory fifth-wheel towing package, it's going to have a nice little diagram that's going to tell you all your wires and what they go to as well and that will make it a lot easier for the installation. We'll go ahead and start off with our yellow wire, yellow to yellow. Our yellow is going to be our left side turn signal stop lamp.

We'll go blue to blue. Our blue wire is going to be our trailer brake. Next is going to be white green to our purple. Those are going to be our backup lights for our trailer if you have them. The gray brown is going to be our parking lamps for our running lights, which is going to be that brown wire on our harness.

The last wire is going to be our green violet to green. We'll just do our little check and make sure all of our wires are snug. We're going to work through and pull on them to double-check them, and then, we'll heat shrink them using our heat gun. This will ensure a nice watertight seal, and you can separate them if you wish to do this. You can see it forming around. Once we're confident we have them all sealed up nice, we'll go ahead and let it cool for a second, and I'll go ahead take that wire loom on that was initially on when we first started, place it back over our wires, and then tape it off. We'll tape it all the way up to our factory tape, and then, we'll also tape it off at the bottom by the connection. Now that we got it all taped off, we'll go up into the bed and drill our hole. Now, we'll go ahead and get our tape measure and measure out a good spot center here in this area on the backend of our truck bed. This whole area behind here and here will be clear, it's just going to be up to customer preference and your preference of where you'd like to have it. Now, our gap here on the backside is going to be over 5" at about 5-1/4". We'll go about 2-5/8" here on the center and we'll make a dot. Then, we'll take and we'll drill out a pilot hole using an 1/8" drill bit. Now, we'll take 2-1/8" hole saw and drill our hole for our 7-way connector. We'll vacuum up the excess metal and shavings before we put in our plug. We'll go ahead and take the end of our connector and pass it up through the hole we just drilled. We'll go ahead and place some dielectric grease on there, part number 11755, just to ensure that we have good contact and longevity of our plug. Take your plug and plug it in. Press it back through, and now, we can go ahead and secure our box. We'll use some 3/4" self-tapping screws to secure in our face plate here. Get it as square as possible and you can still rotate it a little bit. With those all the way down in, we'll not go around the backside and tighten up all of our wires with some zip ties and conclude our installation. Now, we'll go ahead and plug in our 7-way tester and check all of our lights. Plug it in and ensure it's all the way in. You can see our clearance lights come on with those day-time running lamps. We'll go ahead and check out our left turn signal. You can see it flashing there. Right turn signal, brake lights. Now, let's let off the brake and put it in reverse, and you can see our reverse comes on. We're good there. Now, let's go ahead and test out our trailer brake. We'll go ahead and watch the voltage up here, let off, on. We're reading out about 7 gain 00:07:23 on our trailer brake. It all checks out, so we're good to unplug it and hit the road. That will do it for our review and installation of the Hopkins Endurance Quick Install 7-Way Trailer Connector with Universal Pigtail, part number HM47210, on our 2015 GMC Sierra 3500.

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Info for this part was:

Test Fit:
Joe V
Test Fit:
Jared G
Test Fit:
David F
Video by:
Andrew K
Installed by:
Cole B
Video Edited:
Sue W
Video Edited:
Chris R

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