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Install a 4-way trailer connector on your vehicle without cutting or splicing into your wiring. Zero-contact interface sensors identify the current flowing through each wire by simply clamping onto it. Circuit-protected module is made using SMT.
Features:
Specs:
This revolutionary wiring method makes it fast, easy, and safe to add a 4-way connector to your vehicle so you can power your trailer's lights. Unlike traditional tail light wiring harnesses, which either splice into your vehicle's wiring or plug into designated ports in your factory harness, this system bypasses your vehicle's wiring entirely. Just clamp the intuitive sensors onto the individual wires of your OEM tail light harness and let the ZCI system do the rest.
Zero-Contact Interface Sensors
Each zero-contact interface (ZCI) sensor included with this harness is able to read the current that travels through the wire it is clamped onto. Upon sensing the specific modulation of that wire, a signal can be sent along the wire that connects the sensor to the included 4-way flat trailer connector. That signal is then transmitted through the connector to activate the appropriate function on your trailer lights.
Universal, Worry-Free Design
No Splicing, Cutting, or Connecting to Factory Wiring
Because the ZCI sensors can read the signals sent through your vehicle's wires just by clamping onto them, no cutting or splicing is necessary. The system completely bypasses all of your vehicle's wiring. As a result, your trailer's lights will be powered without overloading your vehicle's electrical system. And there is no chance of damaging feedback either.
When using this ZCI harness, you don't have to worry about voiding your warranty, nor do you need to be concerned about any potentially damaging errors on your part if you're not an experienced do-it-yourselfer. And if you have a vehicle that doesn't allow certain modifications - like a leased car or truck - you can install this harness and remove it later with no obvious alteration to the vehicle.
Maximum Compatibility
This wiring harness is universal. You can use it on any vehicle that operates on a 12V, negative ground system. Because installation is so simple, you can easily remove the unit and transfer it to another car or truck at any time.
In addition, the ZCI sensors are able to read the signals sent by multiplex wiring systems and systems with pulse width modulation (PWM) and low-side-switched wiring, making the harness compatible with nearly all automotive wiring systems. This unit also works with both standard incandescent tail light bulbs and LED bulbs.
Built-In Tail Light Converter
Most trailers run on a 2-wire system - wherein the brake and turn signals are carried on a single wire. Many vehicles, however, are built with separate brake and turn signals. This type of system is referred to as a 3-wire system. If your vehicle operates on a 3-wire system, it will need to be converted so that it will be compatible with the wiring system of your trailer. This is done by adding a tail light converter to your wiring setup to combine the brake and turn signal functions of your automobile so that they run on a single wire to properly activate your trailer's tail lights.
This ZCI unit has a tail light converter built in to ensure proper functioning with any vehicle that operates on a 3-wire system. If your car has a 2-wire system and therefore does not need a converter, don't worry. The method of installing the sensors will take into account the wiring configuration of your vehicle so that only the necessary sensors are used, making sure the appropriate signals are sent back to the 4-way.
Installation
This universal harness connects to your vehicle's tail light wiring harness. To connect, just follow the included instructions. There are 4 ZCI sensors included. Each sensor has a colored label on it. Depending on your application, you will need to connect all or some of these sensors to the factory wires indicated in the instructions.
To get the power necessary to operate, the harness must be connected to a 12V power source. The included installation kit provides the hot lead required to connect this module to your car battery. When all connections have been made, connect the hot lead to the black wire on the ZCI power module and run the other end of the lead up to your car battery. Connect the hot lead to the included fuse holder, and then connect the fuse holder to the positive terminal on your battery. Then insert the included 15-amp fuse into the fuse holder.
Once installation is complete, the 4-way connector will be stowed in an out-of-the-way location either within your cargo area or beneath your vehicle, near the trailer hitch. If you choose to mount the connector near your hitch, a mounting bracket (sold separately) is recommended to keep the connector secure.
It is also recommended that you use a small amount of grease on all electrical connections on the 4-pole connector to help prevent corrosion.
Surface Mount Technology
Each ZCI wiring harness is built using surface-mount technology (SMT). This method of construction involves soldering electronic components directly to the surface of a printed circuit board. SMT eliminates the need for leads, which are used in older through-hole technology. The result is a circuit board that is smaller yet provides more routing area and that offers superior performance, reliability, and durability.
Circuit boards constructed using SMT have been shown to perform better under rough conditions with excessive vibration than those made using the through-hole method. And where would vibration be more likely to occur than in towing applications? SMT components also produce less heat, leading to increased durability and longer life. In addition, lower levels of resistance ensure better performance, especially for parts that operate at higher frequencies.
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Great kit, comes with everything needed. There was some uncertainty regarding fitiment of this on a 21 Mercedes GLB250. I’d just like to say that it works perfectly. I was able to determine the left, right and parking light wires (grey with white stripe for right turn signal, grey with white stripe for left turn signal and black with purple stripe for tail light. Don’t attach brake light). The hardest part was running the power wire to the battery but this car has underside fairing so a fish tape made it easy.
I installed the ZCI Circuit Protected Harness in my 2020 Bolt EV. It works as advertised. With a little searching YouTube and chevy Bolt EV forums I located the correct wires. I can confirm that your kit works on my vehicle.
Product did not work. Signals were not picked up. I spend countless hours on the phone with technical support and parts replacement just to find out the product simply was not functioning as described. Returned it for credit. Went to hitch shop; they hard wired the wires into my existing harness.
Excellent experience from the moment of purchase. Great communication and fast delivery. Installation was exactly as shown in the video. I had always been apprehensive about installing a harness but the circuit protection design and detailed install video made it simple as it led me through each step in great detail
Victoria H.
3/7/2025
I agree Mark, the concept of the ZCI is intimidating but you did great! Thank you for sharing your experience and possibly alleviating some concerns of future buyers too.
This wiring harness is everything as advertised. Being able to deliver signal without splicing the turn signal and brake wires is awesome. The install process is pretty involved, but the etrailer videos make it pretty straightforward, the toughest part is finding out which colors go to which wires on your vehicle. A $2 test light and a friend operating the turn stalks and brakes solves this problem. The programming portion is also pretty easy, I did it first time no problem. The power wire running to the 12v battery has fairly thick shielding too which is nice if you need to run the wire under the car.
I was worried about finding a wiring harness that would work with the electrical system in my Audi Q5 hybrid (I’ve heard stories) but luckily this one worked. Install was not easy and the function isn’t ideal though.
I had a really hard time finding the correct wiring diagram for my vehicle so I wound up doing a ton of trial and error. I finally did get it working, but now the driving lights simply never turn off. The instructions said to wire directly to the battery, so I figured this might be the issue, but after drawing power from (what I thought was) a switched fuse, the problem persists.
I’ve considered trying another fuse, but don’t pull a trailer often enough any more to bother. I simply unplug the trailer whenever I park now.
My mechanic loved how easy it was to install and appreciated the bluetooth technology. I appreciate safe transport of my Laser sailboat thanks to this system and etrailer’s awesome hitch. Together, a perfect system for me!
I just finished installing the ZCI kit yesterday. Very easy to install, self explanatory really. The hard part was locating a better place to install the kit.I chose to install it behind the left rear inner trim panel, which was a big pain in the a**. The wires took a little longer to find but not difficult. The power was easily installed because the battery on an Audi SQ5 is located in the back.
Take time to make a clean install, it’s worth it! Works Great!
Having to wire trailer lights through the liftgate is never a joy, but eTrailer makes it as easy as possible with their vehicle-specific videos. Everything fit and my lights work perfectly. This company is a well-run ship, and the phone staff are very knowledgeable.
The Stealth hitch is working well. I really like the stealth approach, when I don't need it, you don't know there is a trailer hitch - the Tesla looks better without it...
The product was relatively easy yo install and is working well. The online video instruction from etrailer was very helpful.
Excellent product and easy to install by a diy. Good videos on YouTube makes this a snap to install in less than hour. Delivery was within the stated window.
I installed this on a 2018 Audi SQ5. It was a 10/10 install, required some sleuthing to find the best way to connect it and required some fabrication. I enjoyed the challenge, and it's entirely doable. Once done the system works great!
Brooke M.
4/7/2025
Do you feel like spilling the beans on what you found out when it comes to the connection and fabrication? I think you could be save other folks lots of time :)
I have noy yet used the trailer lights harness, as trailer project was set aside to complete other projects.
But installation was easy, as instructions are good AND YouTube video's are readily viewable.
The quality of the unit is evident, as module does not feel flimsy,and wire is supple.
Well satisfied that I will like the system, as many others have in posted reviews.
Victoria H.
3/4/2025
I'm happy to hear the install videos were helpful to you, and that this satisfied your needs! If you ever need anything for your future projects, we will be here and happy to help!
Always great service, please update the packaging arrived ok but box was damaged and hitch was breaking out.
etrailer lists this item to fit 2013 bmw x5 and also has installation videos with the x5. after my installation was completed, I was having issues with this device turning on the running lights of the trailer intermittently when the lights on the vehicle were off. I called the manufacturer to help troubleshoot or warranty the product and they said this year make and model is not listed in there wiring list so this vehicle is not compatible!! watching etrailer installation video really carefully, I can see the mistake they made. after they programed this product they leave the tail lights on as they demonstrate all the other functions ( left, right , brake). They never shut off the tail lights to check if they shut off the trailer tail lights. It's a big problem, and cost me a lot of money and time. I had to buy the other curt product that needed to be spliced in and it works perfectly! ultimately, the zci product works fantastic but is not compatible with this vehicle.
I found the products and fast shipping to be “A” team service. I installed a 2” eco hitch on my 2020 bolt ev. The hardest part was getting all the plastic parts off. The hitch bolted on with a perfect fit up. Be sure and cut a tapered opening in the plastic rear cover. The wiring took a little longer to install. Watch all the bolt ev videos you can find. Lift the bolster catch from it’s “T” slot but don’t try to remove the left rear trunk panel completely. Just bend it back enough. Etrailer does supply wiring color codes, but you will see them in two different videos on line. One is a ZCI installation and the other a non-ZCI splice installation. I still have a left tail light on the trailer that remains on with the car turned off. I think it has to do with the module needing constant power. I’m happy with my choices and trailer.
Thank you for your prompt order processing and shipping. The items arrived 2 weeks before the “deliver by” date. That is so much appreciated as it gives me time to install the hitch and wiring harness well ahead of needing it for a move. It also allows me to switch tow vehicles for my handyman business and sell one of them a little sooner.
Huge thanks to your crew!
The trailer hitch and wiring assembly have worked flawlessly. After calling several local installation outfits and receiving estimates of $2,000+ I decided to install myself. I have a little mechanical experience but this was the first hitch and wiring harness for me. This is my wife's X5 so I was a little nervous about popping rivets and pulling the rear bumper cover off, but eTrailer has excellent step by step video instructions by model year. The order included replacement rivets and detailed instructions. They could not have made this any easier. I really took my time and completed the job in about 5 hours. The final install looks professional and clean. The no-splice wiring harness is amazing - worth every penny.
Tools: I was able to easily pop off the existing plastics rivets, and installed the new rivets (included from eTrailer) with pliers pretty easily - you may want to borrow a plastic rivet gun from your local hardware or auto parts store. On the X5 your have to cut a small notch out of the underside of the bumper cover. I happen to have a Dremmel which worked well. You may be able to use a razor blade. The plastic is not that thick.
Pictures are attached.
Thanks etrailer!
It has never worked correctly. The item that I wanted to purchase was backordered with no release date. So, this wiring harness was not my first choice.
The lights stay on even when the car is turned off. Unplugging the trailer is the only way to turn off the lights. We have learned to live with the inconvenience. Very disappointed! Save your money and chose a different item.
Jenny N.
3/26/2024
If the trailer has LED lights this can sometimes happen. Since LED lights take less power the residual power in the 4 way connector is enough to dimly illuminate them. I am afraid, as you have done, the only way to shut them off completely is to unplug the trailer.
This kit works perfectly! A reasonably straightforward installation, though not for a DYI'er who is uncomfortable ripping into the trim and lighting wiring harness of their vehicle. A reasonably accurate wiring diagram is very helpful, but not necessary because trial and error works well with Hall sensors used in this kit (i.e. no cutting and splicing wire is required).
Once installed, the trailer lighting load is easily handled by the power module without feedback to the vehicle lighting control circuit, although my setup does not interface with a trailer brake controller so I cannot judge full performance.
One hint - do not loose the heavy stock reference card that reminds one of the programming routine, While performing other electrical work on my car needing battery disconnection, I can never remember the programming sequence for the trailer lighting controller. Not to worry, though, the product support site has the info.
There is a intermittent outage and I can't figure it out. The problem occurs at start-up (when vehicle is turned on) and lasts about 5-10 minutes then lights on trailer come on. It happens about 20% of time. If you are traveling at night, this is a real problem. Also, the vehicle displays that a device that is draining the battery and when I disconnect the power to the module the message stops. I like the ZCI but I wonder with the vehicles multiplexing signals for lights could be the culprit.
Jenny N.
3/8/2024
It is bummer that it is not working correctly. I reached directly out to Tekonsha about the issues that you were having. It was not something that they had heard of happening with it and so they felt like it would need to be replaced under warranty. I will send you the warranty details in a separate email.
2012 VW GTI (autobahn edition) Installation (DSG)
I had some small issues and hiccups along the way, so in order help out since I couldn't seem to find vehicle specific help, here is what I did. I did buy the CURT 4-way flat connector tester (Item #126) first to make my life easier when testing. It helps. Buy it.
First - start by removing the cargo floor carpet and pulling down the drivers side wall carpet. I did find it necessary to take the moulding trim off the top portion of where the hatch cover locks in, along with the rear seat belt guide trim so I could run the wires to the battery cleanly. There is a few star bolts holding the trim alongside the rear seats when folded down, so just do a search if can’t find it (one cover has to be popped off)
Second - Wiring. This was a little bit of a guess, as I have 3 wires, and my meter didn’t seem to be helpful since they were so small and close together. Here’s what works (drivers side):
- “Stop” module clips over the black/red wire
- Middle brown wire isn’t used
- “Left” turn signal module clips over the green/black wire
- Passenger side right turn signal clips over the green/black wire
- I screwed the ground right into a side structure panel
Running the battery cable was the bigger time suck.
- Stated above I had the drivers side rear panel trim and carpet removed, and I continued removing the front/rear drivers floor sill trim. I ran the black wire along the current loom and tucked it under the floor carpet.
- I then ran it behind the hood latch and towards the top of the metal foot rest, keeping it behind the carpet
- This is where you get to the firewall. There is a piece of foam. Remove it. Now you’ll see a rubber grommet where the clutch pedal would go through if you have a standard. I took that out, drilled a small hole to run the wire through that I attached the wire to a metal hanger to fish up and to the right of the battery box. Fish it up, grab it, and pull it through.
- Slide the grommet back into place (your wire would have been already through it) and snap it on.
- Make your connection to the battery and follow initiation instructions.
I purchased this kit for my 2018 Macan S. The battery is located at the back which makes it easy to connect to the power.
1. remove the side panels to get to the rear lights (they are snap on)
2. remove the spare wheels cover.
3. Unclips the back light connectors (left and right) and remove tape to access the wires
4. with the provided probe, check for left, right signal wires and mark them
5. with the provided probe, check for Brake and Tail light wires and mark them
6. connect the provides sensors to the corresponding wires (arrow pointing to the lightbulb).
7. Make sure to connect Ground wire (white) to the good location on the vehicle. (on the Macan it took me a while to find good connection spot due to the exceptional paint job the Porsche does, you may connected it to the battery to test it)
8. Connect the power wire to the battery, fuse should be removed.
9. run the learning mode as per interactions provided
10. I purchased a 4-pin test connector to help me with testing and troubleshot.
11. tuck in all the wires and, cover the sensors and places back to vehicle covers .
This unit works very well, it was easy to install. making sure you have a good ground spot is very important.
The Tekonsha wiring harness was a bit difficult to install, as the clip-on connections are a somewhat bulky to fit in my Tesla Model 3's tight spaces. The good news is: they work as promised like a charm with our tiny camp trailer's lights. In truth, I have only had to use them once, but cannot imagine that any unforeseen problems would occur with them in the future.
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William
2/6/2025
After a year of use its still working fine. One note: I make sure to unplug the trailer connection when parked. It may be a quirk of the Bolt but sometimes the running lights come on when not in use.