bing tracking image

Tekonsha ZCI Circuit Protected Vehicle Wiring Harness Installation - 2018 Mercedes-Benz GLS- Class

content loading

Customers compare 119250KIT to these similar products

Products Featured in this Video

How to Install a Tekonsha ZCI Circuit Protected Vehicle Wiring Harness on a 2018 Mercedes-Benz GLS-

Shane: Hi, I'm Shane with Today, you're going to be taking a look at, and I'm going to walk you through the installation on Tekonsha ZCI wiring harness on our 2018 Mercedes Benz GLS 50. It's going to give us all of our proper lighting functions so we can safely tow our trailer. Both turn signals and brake lights and our running lights. We're going to have a nice dust cap. It's going to be attached.

It's going to protect our connection points from dirt and debris, it can also be used as a holder when not in use to help keep it off the ground. If you would like a more permanent mounting location, there are brackets available here at and there are no drill mounting brackets. They're going to mount directly to your hitch and then your four pole plug would actually mount to it.So it'll sit about just like that. A couple of great benefits for having or for using the ZCI wiring; one, it has a converter box. The converter box protects your factory wiring from any backfeed if there's a wiring issue with a trailer.

Another thing, this wiring does not have to be spliced into the factory wiring. So if you're the type of person that may lease a vehicle every few years, this wiring can be put on that vehicle without damaging the factory wiring. When you go to get your new vehicle or trade that one in to get your new lease vehicle, you can take this wiring off and put it on the new one.So it can be transferred over to the new vehicle, and you're not damaging any of the factory wiring. Now that we've gone over some of the features, let's show you how to get it installed. We need to start by getting access into the hatch of the vehicle.

We're going to remove this back panel. So we're going to have to T30 Torx head bolts. One on each side. So we'll take a T30 Torx bit remove our two screws. We'll take this panel.

We're just going to pull up on it and we're going to set it aside. To make it easier, go ahead and remove your spare tire. There just should be just a turn knob right in the center. Turn that, and you can pull your spare tire up and you're going to take a trim panel tool. You're going to have plastic fasteners on each side, pull that just like that and pop those out.We're going to take this foam piece out. We're going to pull out these side panels. We're just going to pull on them. They're just sitting in there. Pull out the foam that's inside. Right up behind each taillight, there's going to be three nuts you're going to need to remove. One here, one up here, another one right there, eight millimeter socket. Pull the nuts off. And there's a couple different ways you can do this. If you don't want to take this step, you can actually take your tester that comes in your kit and test each one of these wires to see which one you're going to be using. Because of the wiring kit that we're using, we don't have to splice into the wire. So once you prong that wire, it's going to be open. So what I'm going to do is I'm actually going to pull the light out. I'll unplug it and I'll take the tester and I'll prong or poke the plug itself, so I don't damage any of the wires. Let's take our light, slide it back just like that. Push the black tab, pull it out.And what you do is you take your tester, have somebody sit in the driver's seat and you're going to run through the light functions. I have already tested them, the gray wire with the black stripe, that is going to be the running light signal. And then this white wire with the green is going to be my brake and turn signal. Now we're going to take our left turn since we have a combined system. We're going to take our left turn, we're going to run our wire through, and we'll close the lid. Once you get the wire in, we're going to wrap that. That way the wire doesn't get pulled out and we don't damage the connector. And then we'll find our black and gray wire. Just make sure you're picking your black and gray and not the blue and black, because they're pretty close. And then we'll just set up our taillight wire the same way.Now you close it and then we'll wrap it up with our chrome strip. You want to make sure when you're putting these on your wires, you make sure that the arrow is facing towards the light. I'm going to go ahead and put my taillight back in place since I have that hooked up. We're going to have a couple more wires we need to deal with. Stop and turn because we're on a combined system, we're not going to be using this. Four pole wire, we're going to be running it outside the vehicle. Power wire. We're going to be connecting our wire to run up to the battery. And we have our passenger wire. Our passenger side wire is not going to be marked. We're going to take it and run it underneath like this.Some inaudible 00:05:18. Max, you're going to go ahead and do my ground wire. There is a ground screw right here. We're not going to have to drill any holes for my ground wire, which is my white one. It's going to have the ring terminal on it already. I'm actually going to round it right here to this factory ground. That way, I don't have to drill any the other holes. I only have to use the self-tapping screw that comes in the kit. 10 millimeter socket inaudible 00:05:37 put the ground wire on, then we're re-installing it. We're going to take our power wire. I'm going to go ahead and strip off just a little bit more of the coating here. Put on your butt connector, it come in the kit. You're going to get a bundle black wire like this. This is going to be run up to your battery, go ahead and unwind it, stripped back down, connected into the other side. Where can I put thatNow these are heat shrink butt connectors. If you want to take a heat source and shrink that up, you can. It is going to be inside the vehicle, so we're not going to have contact with any outside elements. So we're not going to have to worry about corrosion. I'm going to go ahead and tape it up though, with some black electrical tape. Our customer is wanting his four-pole ran outside the vehicle. So there's a grommet right here underneath this foam piece that's insulation. This runs right on top of the heat shield, right above the exhaust pipe. So just be careful when running it over to the hitch. If you're doing it this way, make sure it's up off of it. So we're going to start with our black wire. We'll go ahead and run that down through there. This is just an airline tube that I had fed through. Just push my black wire in like that.I'm going to bundle up my wires here and take a zip tie, tape them up if you want. Just clean it up. It's going to be hidden back behind these panels. So now we need to mount our converter box. Your kit's going to come with some two-sided foam tape. What we're going to do is we're going to peel off one side at a time on the back of the box, press it into place, inaudible 00:07:47 off. We're going to find a place to put it. This will be secured up in another way. Now I need to get my four-pole wire down through the hole. You can see that it's not quite big enough. So what I'm going to do is I'm going to take a grinding bit and I'm going to grind out one of these edges, just in one spot, just enough that I can slide this down in there.I'll take my rubber cap that I removed. So you can see what I did is I slice it right to the center here because I have more than just a flat wire going in. I have my black wire going through there. I cut a little notch out of it so that I can fit both of them in and get this plugged back in place. Get my plug in place. Now I'm going to take some black RTV silicone, and I'll fill in the spots where I trimmed it back just a little bit. If you are not going outside of the vehicle like this, you won't need it. Once you've got your wire hooked up on your passenger side, go ahead and reinstall your taillight. Your black wire, which is your power wire and your four-pole plug. Four-pole plug, we need to right over here to the hitch. Our power wire, we need to route up to our passenger side engine compartment. My four-pole wire, I went over top of my hitch, came down right here.I can bundle the rest of this up, zip tie it around my hitch, helped keep it up out of the way here. Zip tie it like that, my power wire. Since we have to go across and up, we have the exhaust we've got to worry about. So what I did is I went right over top of this canister, over top of my axle, across over top of this front bracing to all my factory wiring and these panels. You have a panel here and you have a panel here, 10 millimeter socket. I took out a couple of bolts, pulled down the side, ran my wire underneath all the way up to the front. I fed it right out in this edge right here, actually right over this right here, ran up behind this panel.And that actually comes out right here because my engine is right on the other side of that, what I did is I ran it right up against my frame rail on the outside here, right up through the panel, right up to where my battery positive hookup is. Then as far as bringing my wire up into the end of the compartment, came right up, right through this area right here underneath my fuse panel here over to this side. You don't necessarily have to run the wire that way. You just want to make sure however you're running it, you're staying away from anything hot or moving. Positive hookup is here.So what I'm going to do is I'm going to run it right through one of these holes with this existing wiring, that way it doesn't get pinched. 13 millimeter socket, going to remove that post, take this fuse holder. And what I'm going to do is I'm going to feed it through here first or the end of it, at least. From here, go ahead and add on your ring terminal. We'll take our black wire, butt connector. Then we'll take our heat source, we'll shrink up that butt connector. We'll go ahead and make this connection. Put a ring terminal on the positive post. Re-install, tighten it down and then we'll add our fuse into our fuse holder. Then we can tuck all this down here and we have access to it when we need it. The next thing we need to do is we need to do a learn mode with the wiring.We need to start our vehicle. We're going to turn all of our light functions off. We're going to start with our tail lights. We're going to turn our tail lights on, we're going to leave them on for five seconds, then we're going to go to our brake lights. We're going to turn our brake lights on for five seconds and then each blinker for five seconds. Once you get that tested, we're going to make sure that everything is working back to the plug. We're going to be using part number I26 to test it out. We have our running lights, brake lights, left turn, right turn. Once you've tested everything, you know everything's working correctly, you're ready to go. Again, I'm Shane with I hope this video has helped you, whether you're still deciding or installing Tekonsha ZCI wiring harness on your 2018 Mercedes-Benz GLS 450..

Info for this part was:

Employee Joe V
Test Fit:
Joe V
Employee Randy B
Test Fit:
Randy B
Employee Andrew S
Test Fit:
Andrew S
Employee Brent H
Test Fit:
Brent H
Employee Shane H
Test Fit:
Shane H
Employee Robert C
Test Fit:
Robert C
Employee Conner L
Test Fit:
Conner L
Employee David F
Test Fit:
David F
Employee Ryan G
Test Fit:
Ryan G
Employee Zack K
Video by:
Zack K
Employee Andrew K
Video by:
Andrew K
Employee Kathleen M
Video by:
Kathleen M
Employee Zach D
Video by:
Zach D
Employee Jonathan Y
Video by:
Jonathan Y
Employee Michael B
Video by:
Michael B
Employee Thomas T
Video by:
Thomas T
Employee Schuyler H
Video by:
Schuyler H
Employee Joshua S
Video Edited:
Joshua S
Employee Jacob T
Video Edited:
Jacob T
Employee Dustin K
Video Edited:
Dustin K
Employee Chris R
Video Edited:
Chris R
Employee Cole B
Installed by:
Cole B

At we provide the best information available about the products we sell. We take the quality of our information seriously so that you can get the right part the first time. Let us know if anything is missing or if you have any questions.