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Wiring up a trailer doesn’t have to mean chasing down wires or making splices. The Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector plugs straight into the factory connector, giving you a ready-to-use 4-flat output for your trailer lights. It’s a plug-and-lead setup that keeps your factory wiring intact and avoids any guesswork.
Once installed, the 4-pole flat connector provides the essential lighting functions—running lights, brake lights, and turn signals—so small trailers, utility haulers, and boat trailers can be seen clearly on the road. The visible connector design makes hookup easy, and the standard format works with most light-duty trailers.
Some vehicles don’t send enough power through their tail light circuits for trailer lights to work correctly. This harness includes a powered converter that draws power directly from the vehicle battery to run the trailer lighting system safely and reliably. That extra power protection helps prevent overloads on the vehicle’s sensitive electronics.
Even if your vehicle came with a factory tow package, this kit makes adding trailer wiring straightforward. The plug-in design connects to the existing wiring in minutes, and the powered converter handles the rest so you can tow confidently without extra modifications or factory parts.
Customer Satisfaction Score:
96% were satisfied with this product
4% of customers were not satisfied
Ratings & Reviews
Connected easily and worked perfectly.
Great service!!
Looks great. I plan to install it soon.
Shipped quickly. The installation video on the website was perfect. Everything worked like a charm.
As advertised. Easy to install and good quality.
Everything fits and works perfectly. I should have also ordered the holder for the 4-pin connector. It would have saved me a trip to the hardware store.
I liked the quality of the parts and the perfect fit for my 2026 Toyota Hylander
Easy instructions and video online to install yourself
Simple to install. Took about 20 min
did not work out
factory wiring and curt did not seam to work out
A little pricey, but lights work great, bright.
Exactly what you need to add trailer lights to a Lexus TX350 that doesn’t have the factory trailer package. On the TX350 you only have to remove the 3rd row armrest to plug in the control box, the instructions have you removing more panels. Also the cable that comes with this kit that has the 4 pin flat trailer outlet must be used. I already had the other kit for the factory tow package on there and assumed the wiring would be the same. It isn’t!
Very easy, Install plug and play pretty much!
The trailer hitch and other parts came in 2 days after ordering. The install when smoothly and the connecting of the wire hardness was surprising easy.
Compatible with 2025 Lexus TX 500h (Factory Tow Package) – With Caveats
I installed this on my 2025 Lexus TX 500h. While I initially had significant issues during the setup process, the harness ultimately solved my problem and functions properly with the vehicle's factory tow package.
The Good:
Fully compatible with the Lexus factory tow package once installed.
Successfully resolved my trailer lighting issue.
Areas for Improvement: I bought this kit but only need the small pigtail from the factory wiring harness under the rear bumper (driver's side). In a sense the part i used probably should cost $25 max but I end up spending $108 out the door.
Plug and play, super easy to install, no cutting or splicing, looks and feels factory! Highly recommend
Over the last twenty years I have purchased 3 new vehicles. Each time I have then purchased and installed the trailer hitches and wiring harnesses from etrailer. Each time the products have fit the individual auto perfectly. The instructions are very thorough and precise. Their prices are very reasonable. I highly recommend etrailer for their auto accessories.
Easy to install with the factory harness in place. Instructions and video provided by E-Trailer made the process seamless. Customer Service Rep Amy was fantastic to work with on the recommendation and purchase.
Installation on a Grand Highlander is even easier than the instructions which assume a regular Highlander. You only need to pop out the cup holder, and the plug is easily accessible right there. No need to remove the extra fastener or side trim panel at all!
Gwendolyn Y.
5/6/2025
Hey that is easier! I bet that made the install a breeze. Any fun plans of what you will be towing, Tom?
I was pumped about this one. 2025 highlander xle already has a line running to the receiver so just need to pop the rear driver panel plug the harness in and then go plug in the trailer plug in the back at the pre-installed plug.
Correct fitment for 2026 Highlander Hybrid Limited. Nicole checked in to make sure I got the product. The installation guide video for the 2026 Grand Highlander is perfect. Installation was easy except finding the main plug that was stuffed wayup high in the side panel.
Good quality but I needed to swap turn signal wires in harness. Had factory light module but it wouldn’t work. Needed to use Curt module.
Plug Harness plugged in nicely, once correct plug is located.
There is a problem with the video at about 3:30 mark, as mentioned in the review above this one.
The guy talks about the plug, that is attached via car body clip.
It is located , where you pop it open by weather stripping.
This is not the correct plug. I popped it out as suggested, and pulled cover off, and it is a completely different connector.
The correct plug is mentioned in the video before this incorrect plug is mentioned.
Removed tape as mentioned for this plug and plugged in the this unit.
Followed the rest of the directions from there.
All the rest was good.
Please tweak the video to get this correct.
Thank You
The video that shows you how to install this in a Toyota Highlander is not accurate. Your instruction video shows the wrong harness to plug into. Very confusing but ended up figuring it out using a different companies install instructions. I would recommend removing the video that you have on the Highlander install and redoing it showing the proper harness to clip it into.
Kate F.
6/25/2026
Thanks for bringing this to our attention WeisGuy. I am going to have my video team review the video as we like to have out information and videos accurate.
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.
Gwendolyn Y.
3/13/2025
Hitch looks great! Also love your logo :)