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Running trailer wiring can be a hassle if you have to splice into the factory harness. This Curt T-Connector makes it easy with a plug-in design that connects directly to existing vehicle plugs. No wire cutting, no guesswork—just a clean, hidden install that’s ready for towing lights right away.
Once installed, the 4-flat connector provides all the basics your trailer needs—running lights, turn signals, and brake lights. The built-in powered converter combines separate vehicle circuits into standard trailer light signals so everything works correctly when you hook up.
The included converter box keeps the vehicle’s sensitive electronics safe while sending steady power to the trailer lights. It uses direct 12-volt battery power through a black lead and grounds through a white wire to maintain consistent brightness and reliable operation over time.
If you decide later to add electric brakes or charge a trailer battery, the 4-flat connector from this harness can plug right into a 7-way adapter like part #37185 or #ETBC7. That means you can expand your setup without having to redo the wiring you already installed.
Customer Satisfaction Score:
91% were satisfied with this product
9% of customers were not satisfied
Ratings & Reviews
Curious why you need to connect to the battery directly.
Very seldom do I receive this level of professionalism. I paid a fair price, and received an outstanding buying experience.
have not installed item yet TKS
As always, great price, great product. I didn't have wait very long for delivery. Thank you !!
I like the 2 inch hitch and the video i nstructions!
Quality part for my wife’s Mazda CX-5-30. Service from e-trailer is excellent. They are very attentive in every aspect of the purchase and shipping.
I’ve been lucky this year to find 2 companies that have beyond excellent customer service. e-trailer is one of them. I can’t say enough for the way they helped me when I ordered the wrong product. Way above and beyond! This is pretty much the only company that I use for this kind of products. Price and service is what sells me so being a past RV owner, I’ve bought plenty! I highly recommend this company!
This Did Not work on my 2021 Mazda CX30, it made all the trailer lights blink. Very disappointing after a 3hr install job. Curt needs to do better with their RandD. I am glad I didn’t pay a mechanic to do this. The T one kit worked correctly on my car, I suggest you go with that one.
I'm from Canada and looked many places for this item. Sources in Canada did not have inventory, and it is hard to find a US based vendor willing to ship to Canada. The representative at etrailer was great. The process to find and purchase this item was easy, it was offered at a fantastic price and even with exchange, duty, and shipping, it cost less than the same item offered anywhere else - Canada/US. Shipping was quick with detailed tracking. Was a real pleasure doing business with this vendor. Highly recommend.
This does not work on a 24 Mazda CX-30 even though it comes up in the results. Both left and right lights will blink when you use either the left or right signal. You need to buy the Tekonsha adapter, which works fine.
Victoria H.
10/28/2024
Will, This is a very common issue for the t connectors if it is not grounded properly. You will want to make sure that you have the ground attached securely to the clean, bare metal surface of the frame.
Very easy to install.
Curt wiring splices into existing wires with no problem.
Electrical components work well and are durable.
Wiring, and hitch on my wife’s 2014 Scion XB, installed 2014, are still in good shape. No problems.etrailer seems to have very responsive support, except I haven’t had to use their support services but once.
This is why I continue to purchase from etrailer.
Turn signals ground out through the marker lights. To correct you have to drive with Headlights on when using trailer. Curt sent replacement, new one works same way.
e trailer had exactly what I was looking for both in the hitch and wiring harness for my vehicle. Easy to find on the site with comparisons and advice both in product and installation. Fast shipping was also a plus.
The wiring harness was very simple and straightforward to install. The power wire took much longer than expected only because of the well laid out undercarriage panels Mazda installed. The power wire is totally protected by taking the time to loosen the panels and run the wire inside the panels.
Thank you everything worked pretty much perfect except when you have the trailer connected, you have to have the headlights on on your car. Otherwise the blinkers will act stupid not not a big big deal. If you don’t have your headlights on, that’s OK too you just don’t use your blinker I guess the brake light still work fine with or without.
Super Easy to put in. The 12V from the battery was easier to run/hide than I thought. Can't even tell. Took less than 30 min to install. No cutting no modifications. I wish there was a body plug in the car to run it under, but not a big deal. Both hitch and harness install was about 1.5hrs for both. Super easy.
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Kate F.
11/12/2025
I’m really sorry you’re having trouble with your trailer lights Walter. That’s definitely frustrating, especially after installing a new harness. Most of the time when the lights only work correctly with the headlights on, it turns out to be a ground issue rather than a bad harness. On your 2021 Mazda CX-30 with the Curt 56450, make sure the white ground wire from the module is attached to bare metal inside the left rear cargo area, since that spot is often painted or sealed and can block a good connection. It can help to remove the screw, sand down to clean metal, and reinstall with a star washer. Also check the black power wire running to the battery to be sure the fuse and terminals are clean and tight. Finally, take a look at the trailer’s ground; if it’s weak or corroded, the lights can try to ground through the running lights, which makes them work only when your headlights are on. Please let me know if this fixes the issue.