To see if this custom-fit item will work for you please tell us what vehicle you'll use it with.
Thank you! Your comment has been submitted successfully. You should be able to view your question/comment here within a few days.
Error submitting comment. Please try again momentarily.
When you already have a factory tow package, adding a working trailer plug shouldn’t mean rewiring the whole setup. The Curt T-Connector simply plugs into the existing factory connector to give you a 4-flat trailer output. No cutting or splicing—just a direct fit that gets your lights working fast.
If your original 4-way is broken or corroded, this harness is built to replace it cleanly. It snaps into the same factory socket, restoring your running lights, brake lights, and turn signals so you can tow safely again without chasing wiring issues.
Sometimes you need more than basic lighting—like powering trailer brakes or charging a trailer battery. This 4-flat connector makes it easy to step up using common adapters like part #37185 for simple lighting or the #ETBC7 kit if you’re adding a brake controller. It’s a flexible base that grows with your towing setup.
Built by Curt, this harness uses solid connectors and weather-resistant wiring that hold up to road use. Once it’s plugged in, you’ve got a dependable connection every time you hook up your trailer.
Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.
Today we're going to be taking a look at part number C55251, this is the Curt T-connector vehicle wiring harness with a four fold flat trailer connector. You can see here that the four fold flat connector has a dust cap on it, that way you can protect the connection points when the connector's not being use. This product is designed to fit the 2002-2005 Mercury Mountaineer, 2002-2005 Ford Explorer and the 2003-2005 Lincoln Aviator. It's going to provide the four way flat trailer connector at the back of the vehicle to power your trailers signal lights. This is designed for use with a factory tow package. It is compatibility with five pull, six pull and seven pull adapters.
Adapters are sold separately. This system is going to connect quickly and easily, you don't have to worry about cutting or splicing any wires, all you have to do is locate the connection point behind the rear bumper and plug in the harness. It's going to be a perfect match, when it comes to the connectors, push them into one another, they're going to snap off together for a nice tight secure fit. The kit's also going to come with some zip ties that way you can secure any excess wiring up and out of the way. Once your installation is complete the four way connectors going to be stowed beneath the vehicle, under the trailer hitch. You can loop it around the safety chain loops or you can use a mounting bracket. You're mounting bracket is sold separately but we do recommend that to keep the connectors secure.
It's also recommended that you use a small amount of dielectric grease on all your electrical connections to help prevent corrosion. If you need some of that you can find that here at etrailer.com, it is going to be sold separately. That's going to do it for today's review of part number C55251.
Customer Satisfaction Score:
88% were satisfied with this product
12% of customers were not satisfied
Ratings & Reviews
Perfect fit. Puug and play works great!
Fits perfectly
Product arrived just as discribed. Follow up by sales staff was excellent.
snap in clip up done. it doesn't get any easier. Fit was fantastic on my 04 Explorer
Products matched my vehicle perfectly. Instructions were clear. I would definitely buy from them again.
Fit perfectly got my trailer lights working again thanks
I have been using it for a year now and it functions perfectly. I recommend etrailer.com!
This harness was an easy direct-fit replacement for my '03 Ford Explorer. My only hassle, and that's an exaggeration, was that it took a good bit of force to get it to insert all the way into the factory connector; I used large channellocks for the final squeeze. Works perfectly. etrailer staff has always been very helpful.
Product worked great with my 04 Ford Explorer. Only thing is that the trailer plug didn't fit in the original bumper bracket so it is dangling loose until I can get a bracket that fits to secure it in place. Still satisfied though.
Do you have a question about this Custom Fit Vehicle Wiring?
Info for this part was:
At etrailer 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.
Mike L.
3/28/2018
My favorite way of securing a 4-pin trailer connector is the Eclipse, part # 306-X6019 from Ecohitch. The Eclipse features a super-strong magnet that will secure your trailer connector to the trailer hitch or other ferrous metal surface that is nearby.