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Adding trailer wiring usually means tapping into your vehicle’s circuits, but this harness eliminates that step. The Curt T-Connector plugs in behind the tail lights using factory-style connectors to create a 4-flat trailer plug. There’s no splicing or guessing which wire does what—just plug it in and you’re ready to tow.
Modern vehicles don’t like extra electrical load on their lighting system. This harness includes a powered converter that draws power directly from the battery through its own fuse. That way, the trailer lights get a clean 12-volt feed while your vehicle’s wiring stays protected from overloads or shorts.
Once installed, the 4-flat connector provides running light, turn signal, and brake light functions to any small or mid-size trailer. It’s the standard setup for most utility trailers, boat trailers, and campers, giving you all the signals needed for safe towing on the road.
The included black power wire runs straight to the positive terminal on the battery. It’s a straightforward route that ensures the converter always has reliable power. With solid grounds and a dedicated fuse holder, you get consistent performance without flickering or dim lights.
If you ever step up to a trailer with electric brakes or need a 12-volt charge line, this 4-way harness can be paired with kits like the ETBC7 to add a full 7-way connector. That means you can start simple and expand later without redoing the wiring you’ve already installed.
Customer Satisfaction Score:
97% were satisfied with this product
3% of customers were not satisfied
Ratings & Reviews
Our previously installed harness quit working. Something got fried inside the converter. The part we ordered from etrailer was literally a snap to install and works exactly as it should. So my trailer lights are back in business! The price was right, shipping time was acceptable and it took me about an hour to remove the old harness and install the new.
Regarding installation on a Ford Transit: I've seen several comments about the difficulty of making connection to the battery, which is under the drivers seat. Our van has a remote positive terminal in the engine bay to make jump starting easier. Our original harness was wired to this terminal, so I just kept the wiring in place.
yet to install but quick shipping makes me a satisfied customer
Amy was very helpful and knowledgeable about the products that I purchased.
Very easy install. Worked perfectly
Will not work on a 2026 Transit 350. The website may have been changed to reflect that now.
Perfect for our transit van. super easy to install although the wiring was rather difficult to get right. Just the thing to pull our boat trailer with ten kayaks! and a great deal.
This is easiest wiring harness I have had to install on my Ford Transit. I will definitely be always using etrailer from now on, for all my wiring harness needs.
Briann did a great job with help to get harness hooked up
Sara was a huge help!! Thanks again etr ailer.com!
Installing was simple and easy arrived on time very pleased with purchase and vendor will use again in future
Very easy to install. No need to cut any wires.
Love the how-to install video that you guys provide for so many of the products you sell!
Light kit fit my 2022 Ford Transit like a glove. Plug and play.
Exactly as advertised and easy installation for a reasonable price!
My order was processed and shipped quickly. The packaging was very sturdy and everything arrived intact. I haven't installed it, yet, but they provide multiple installation videos. I wouldn't hesitate to order from them again.
Liked the kit but found a better way to install without cutting grommets. Mounted below drivers side tail light. See pics. Power wire was run all the way to the fuse box under hood instead of battery under drivers seat. This kept all wiring outside keeping all grommet seals intact, and saving time on removal of interior panels which are difficult with 15 passenger seating still installed.
This is an easy to install kit, and the install video made it even simpler. I chose to mount my wiring on the left doorpost, where it can easily be pulled out through the rear door weatherstripping when needed. I was able to keep all wiring inside the van compartment and frame rails. Two hopefully helpful comments:
* In order to mount to the door rail, it is necessary to splice in a couple of feet of wire to the green wire between the two light buckets. By cutting this wire, I was able to snake it through the frame tubing under floor behind the rear door latch. I did not have any wiring outside the vehicle.
* There is a wiring lug available on the side of the driver's seat, adjacent to the battery compartment, which may be a more convenient lug to attach the hot wire to. The video shows running the wire all the way to the engine compartment.
Best of luck.
Above averaage construction, but the main power wire was about three feet too short.
Harness not long enough to go from side to side to hook to tail lighta
Excellent - easy install what I call a plug and play. just enough power wire to run to battery (no excess)
Everything thing was there that the installer needed that E Trailer recommended.
Great service from the start to the finish. Thanks E Trailer
Easy install, watched video to ease installation! Fast shipping!
This was a necessary product for my Ford transit van. Fortunately, I am experienced with electrical wiring and have electric components on hand. The product itself is a good product and didn’t have any issues with it after installing it. What really is disappointing is that it did not have enough electrical wiring to run throughout the van. I had to install additional wiring as as well as supply my own fuse and various wiring terminals to make all the connections. Video instructions were very helpful on getting the wiring kit ran through the van, and the videos were very helpful to follow. Ordering from etrailer was easy. Was able to quickly find and identify the part needed. And the whole ordering process was a breeze. Etrailers communication was fantastic on the digital side.
Kit works as advertised, power wire and RH tail light wire were both about 2 feet short. Fortunately I had wire and splices to finish the job, but would suggest adding about 3 feet more wire to each of the short harnesses. I have done wiring installations professionally for 40 years.
It went in pretty easy. The instructions seemed to indicate that you run the main 12 V power line from the battery through the cabin back to the rear lights. Which I suppose would be fine if you had a work/cargo van. Mine is finished so it took some creativity and problem-solving to figure out a routing that wouldn’t leave exposed wires for people the trip over or get caught on.
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Mark M.
2/3/2020
Still working as advertised. No issues at all.