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Wiring a trailer usually means cutting into factory wires, but this harness skips that. The Curt T-Connector plugs right into the existing tail light connectors to give you a 4-flat trailer plug. The powered converter takes its signal from the tail lights but draws power directly from the vehicle battery, so the trailer lights don’t overload the vehicle circuits. It’s a clean install with plug-in connections and a dedicated power wire for reliable output.
Many vehicles can’t handle extra load on their tail light wiring. This harness avoids that problem by pulling power straight from the battery while using the tail light circuits only for signal. That setup prevents shorts or heavy current draw from damaging sensitive electronics and keeps everything protected. The power wire must be run to the battery to maintain full circuit protection and warranty coverage.
Whether your trailer uses LEDs or standard bulbs, this harness has enough output to keep them shining bright. It delivers 3 amps per circuit for stop and turn lights and 6 amps per circuit for tail lights. Because LEDs draw less current, there’s room to add extra fixtures if needed without overloading the system.
With its 4-pole flat connector, this harness provides all the basics—running lights, turn signals, and brake lights—ready for most small to mid-size trailers. It’s also easy to expand later with an adapter if you need a 5-way or 7-way plug for more advanced setups like brake controllers or reverse lockout solenoids.
Good grounding is key for trailer wiring, and this harness includes a white ground wire that must be attached to bare metal free of paint, dirt, or corrosion. A proper ground helps prevent signal loss or flickering lights so everything functions consistently once connected.
Do not connect the power wire to a 12-volt accessory outlet; doing so can overload the circuit and void the harness warranty. Power must be drawn directly from the vehicle’s battery to maintain circuit protection and ensure proper functionality.
Customer Satisfaction Score:
94% were satisfied with this product
6% of customers were not satisfied
Ratings & Reviews
Had everything I needed for wiring my trailer lights. I connected the 12 volt power wire to the 12 volt outlet in the trunk b/c I didn’t feel like running a wire the length of the van to the battery. Works great.
Good product, holding up well. My only suggestion would be better instructions on routing the auxiliary power lead. I ended up tapping into an existing power lead adjacent to the rear access panel which saved running the separate power lead under the undercarriage to the battery per the instructions. Didn’t seem like a good idea to have this wire exposed to the elements.
First ETrailer.com provides exceptional customer service and order processing.
The product was constructed very well but the holes on the trailer hitch did not align well with the vehicle frame and I needed to use a jack to force the hitch into a position where I could struggle to get the bolts started and had to drawer the hitch to the frame it was approximately 1/2" shy of the width needed.
I have not installed the wiring yet .
Exactly as advertised! The installation video made all the difference, even though there were differences between the video vehicle and mine. I wouldn't hesitate to do it again.
Hello. I'm going to write this review as if the reader of this post has never ordered and or installed a hitch and or vehicle wiring harness kit. Oddly enough the kit was slightly more difficult than the install of the hitch. Admittedly I am a first time purchaser and installer of these items, I needed to haul around a golf cart I recently purchased so I needed a hitch so I could accommodate my trailer also a recent purchase. The hitch install went relatively easy ( to make the install a bit easer have a friend assist you) although I did installed the hitch by myself. The install of the harness kit went somewhat straight forward, the directions could have more pictures. One mistake I made was installing the fuse (to the wire that runs from the battery to the wiring harness) before I routed the wire to the rear of the vehicle. Also the only special tool you'll need is a torque wrench. All in all if a person with a small amount of mechanical ability and patients the install of hitch and wiring harness kit is not difficult at all. 2009 Mazda 5 total time of installation about 2 hours. The hitch was made of heavy gauge metal and the wiring harness kit came with all the necessary parts for a complete installation. I did check Walmart and the ball (that I also purchased from e trailer) was a few dollars cheaper. I would refer this this company and their website to a friend. The personnel taking the orders was also very informed about their products they were selling. Good luck.
It's has been working with no problems
This is the second wiring harness I have purchased for my vehicles from eTrailer.com and I have been very pleased. The installation video was most helpful. I watched it completely through before I even started in order to have a clear idea of what I was in for. Then, I referenced parts of it again as I went through the installation process. It took a little longer than I anticipated, but everything looks good and works great!
Very Heavy Duty. No problems.
Installed
- 75531Class III Hitch
- Curt T-connector Wiring Harness
- Draw-tite Ball Mount - 3/4 Rise/2 Drop - 10-1/2 Long - 6k
- Hitch Ball - 2x1x2-1/8 - 7500 Lbs
on 2010 Mazda CX-9.
Most work done by my 16 year old son. All works awesome. With the clear videos, great customer service, many other companies could learn a lot from etrailer!
The transaction was smooth and easy. Installation was a breeze for the most part. The threaded holes in the frame of my SUV has some surface rust which made it difficult to insert the trailer hitch/receiver bolts. I recommend using an appropriate sized tap and use it to run through the bolt holes first before inserting and tightening the mounting bolts. Use a little bit of anti-seize paste on the bolt threads to ease installation of the bolts and protect them from corrosion.
The wiring kit installation was also easy enough. Just take your time and follow the directions and you won't have any issues.
Everything worked just as advertised. The product itself was great but the real star here is the install video etrailer has done. The instructions that come in the package are extremely vague and, I suspect, probably targeted at professional installers who have done this sort of thing before many times over. Even as a relatively experienced/accomplished DIY guy, this project would have been a non-starter for me without the video.
Most of the install is pretty easy stuff as long as you are familiar with the types of clips/screws/etc that are used to hold the plastic bits of the interior of your car together (video does a great job showing you what/how to remove). Where things get dicey is when you have to run the power line *underneath* the vehicle from the rear bumper all the way to the battery! The video does a great job showing a good route to take, but you'll note in the video he did the work with the benefit of a lift. At home, you'll definitely need a good set of safe ramps and some good lighting to get the job done. It can be done for sure (I did it), but it took me a good while.
The item is just what is wanted and at the right price. Fast delivery. Only problem is with UPS is they deliver to businesses first and residents.
This is not the first time I have used "etrailer". Always got the right items and delivery was quick.
Great Job to everyone at etailer.
Bruce
4/20/2019
Great
Ordered a Class 3 Hitch for my 2010 AWD Mazda CX-9 - Super easy transaction all the way through installation. Ordering was easy, delivery was on-time, exactly what I ordered - While having has this hitch professionally installed, with Wire Harness, and 7 pin connector - Total ($80.00) I felt it well worth the price. Here is what I am towing - entrusted to an etrailer hitch
Thanks for a transaction that I can look back at and say "smooth" @ etrailer.com.....
This wiring harness was super-easy to install. The most difficult part, by far, is running the wire up to the battery. If you have an automatic transmission (on a Mazda 5), you can run the wire completely on the interior (google it, there's a very good DIY). However, if you have a standard transmission like I do, the very convenient hole where you can put the wire through to the engine compartment is taken up by the clutch.
My only complaint with the harness is that the plug made a poor connection at first. After the initial install, the left turn signal/brake light didn't work on the trailer. After about an hour of troubleshooting, I gave the 4-flat plug a squeeze with a set of pliers and compressed the metal contact points by a hair. After that -- no problem.
Premade harness made it super simple to hook up. Took me a total of 30 minutes to have it installed and working. Highly recommend
The wiring did not take long at all. For me all the wires were long enough to make all connections. The videos show you have to have the pig tail come threw the hatch and over the bumper. I found on my 2012 cx-9 there was a plug on the back wall a few inches from the jack on the drivers side that was big enough from the plug to go threw.
Andrew
7/18/2013
What video? I need a video link if possible
Everything worked as advertised! Just like everything else I have ever bought from etrailer.com
Yes, you may have to crawl under your vehicle to run the power connection. Took a little longer to install the hitch and wiring harness my wife was watching. :) Really, you can't go wrong with these guys and yes indeed, they stand behind what they offer!
Intake this in a 2013 Mazda5 while installing wiring to power the car taillights with RV lights for towing on a dolly.
If you follow the instructions and run the power wire down the driver's side of the car and install the converter on the driver's side, the install is flawless.
It has only been used to per the lights on the tow dolly, but it works perfectly. The converter, wiring and connectors are all of excellent quality.
The trailer hitch is a great fit. It did a little bit of fanaglyinhg to get it on properly but nothign to serious. I was able to do most of the work by myself but needed a second pair of hands to get it the intial bolts started.
Took about 4 hours to get it on as there was some level of difficulty to get it on as I was just working with jack stands hands, knees, and a rachet.
Unfortanately My car got recked a month later. I did get to use it 3 times before this and she did the job, no issues. Pulled about 1700 lbs the first 2 times over 100 miles and about 1900 lbs for about 50 miles.
For saving about $120 for someone putting it on for me, it was worth it. The price comparision buying it here vs other places etrailer has a good price and the product is good. I will note it did come in a semi weak box and had a few scrapes on it but noting extremely noticeable and nothing that would cause issues to the integraity of the hitch plus it's under the car, astectics shouldn't matter that much when it comes to saving some money vs buying it elsewhere.
I give it 4 stars becuase nothing is perfect and it was really worth the savings as it was solid hitch the did job with no issues.
Quick processing and shipping, perfect fit to our 08 Mazda 5.
Quality seems very good,directions are simple and straight forward .
Found a U Tube video with this product exactly, with hints on simple removal
of interior panels to simplify installation.
Dan
1/19/2018
Easy hook up, very dependable.Thank you for a good product for my Daughters Mazda 3.
Installing the wiring kit was pretty straight forward. Especially if you watch an instillation video. If you have a lower sitting vehicle, you may have a tough time with the power wire. I was able to dive mine up ramps and get under it. I have one big problem with it, with everything hooked up my automatic hatch won’t close. As soon as I pull the fuse for the module, it works fine. I’ve contacted Curt and am awaiting a response. I’ll see how that goes and adjust my review accordingly. It is a 2009 Mazda CX-9.
Bob K.
10/19/2018
After contacting Curt, they sent a new harness. It has worked perfectly ever since. I’m completely happy with the kit.
Product installs just like the instructions say. Routing the black wire to the battery area was the toughest part of the install. I used a wire to poke down from the battery area, taped the black wire to it underneath the vehicle and then pulled the black wire up to the battery.
Circuit tested and everything seems to be working. Next step is to check it out with a trailer.
Dan M.
9/9/2014
No problems using it and I like that it stores inside the vehicle when not in use, which is most of the time.
It came early!!! Everything was included so I didn’t have to spend any money on extra parts
I give high praise to the trailer hitch and wiring harness kit I purchased last year! The installation couldn't have been easier and the hitch fit like a glove on my Mazda CX9. The instructions were clear and easy to read. Thanks for a great selection of products!
John S.
3/24/2018
Still very pleased with hitch and wiring kit a year later.
Working perfectly fine after one year. I did the install myself, took me a little more than an hour. Customer service just wrote me to ask for a review, and I view it as a positive business practice - making sure everything works fine after one year, giving a chance to customer to express anything if something went wrong in the mean time... Thank you!
I ordered my hitch and wiring harness on a Saturday and got them on a Tuesday. Installed the hitch on Tuesday night by myself and it fit like a glove.
Great service and great products!
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Greg
5/9/2022
Excellent