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T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

Item # 118325
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Custom Fit Vehicle Wiring 118325 - Custom Fit - Tekonsha
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Quickly and easily install a 4-way trailer connector on your vehicle with this custom wiring harness. T-One connector plugs directly into existing wiring - no cutting, splicing or tapping required. Includes tail light converter. 1-636-306-4830 to order Tekonsha custom fit vehicle wiring part number 118325 or order online at Free expert support on all Tekonsha products. Guaranteed Lowest Price and Fastest Shipping for T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector. Custom Fit Vehicle Wiring reviews from real customers.
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  • Reviews (215)
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  • Why etrailer?

Tekonsha Custom Fit Vehicle Wiring - 118325

  • Custom Fit
  • Trailer Hitch Wiring
  • 4 Flat
  • Converter
  • Tekonsha

Quickly and easily install a 4-way trailer connector on your vehicle with this custom wiring harness. T-One connector plugs directly into existing wiring - no cutting, splicing or tapping required. Includes tail light converter.


  • Provides a 4-way flat trailer connector at the back of your vehicle to power your trailer's signal lights
    • Compatible with 5-pole, 6-pole and 7-pole adapters (sold separately)
  • Connects quickly and easily - no cutting or splicing of wires
    • Locate connection points along frame rail
    • Plug in T-connector
  • Includes a tail light converter to ensure that your vehicle's wiring matches that of your trailer
  • Constructed of 16-gauge bonded wire
  • Comes with dust cap for 4-way flat connector


  • Maximum amperage:
    • Stop/turn lights: 2.1 amps per circuit
    • Tail lights: 4 amps per circuit
  • 1-Year limited warranty


This custom-fit T-One connector plugs into your vehicle's wiring harness, which is located beneath your vehicle, along the driver's-side frame rail.

Once installation is complete, the 4-way flat connector will be stowed beneath your vehicle, near the trailer hitch. A mounting bracket (sold separately) is recommended to keep the connector secure.

It is recommended that you use a small amount of grease on all electrical connections - the plugs on your automobile and the 4-pole connector itself - to help prevent corrosion.

Tail Light Converter

A tail light converter is built into this T-One connector. Because most trailers run on a two-wire system - wherein the brake and turn signals are carried on one wire - the separate brake and turn signals from your vehicle's three-wire system need to be combined so they are compatible with the wiring system of your trailer. The tail light converter combines the brake and turn signal functions of your automobile so that they run on one wire to properly activate your trailer's tail lights. Note: This will not affect how the tail lights on your vehicle operate.

118325 Tow Ready T-1 T-Connector - 4 Wire

Installation Details 118325 Installation instructions

This Product Fits The Following Vehicles

California residents: click here

Customer Reviews

T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector - 118325

Average Customer Rating:  4.9 out of 5 stars   (215 Customer Reviews)

Quickly and easily install a 4-way trailer connector on your vehicle with this custom wiring harness. T-One connector plugs directly into existing wiring - no cutting, splicing or tapping required. Includes tail light converter.


Small, well-built wiring harness is just what I need for my vehicle, and customized to fit it, so no guesswork or trying different combinations needed.

Its been holding up, but I have not connected it in nearly a year. I will try to do so later this week, because I am finally moving the trailer after upgrading it.
Colin - 05/31/2022


The wiring harness was easily installed and has functioned perfectly for a year now.

Moved the harness to a second Ranger and it still works as well as the first day I used it!
Brent W - 12/18/2021


One year ago I bought this wiring harness for my 1999 Ford Ranger XLT after trying to repair and fix the pigtails that the previous owner of my vehicle installed. After installing this system, I noticed an immediate benefit of having it plug into the existing factory wiring harness for the lights everything works phenomenal and perfectly every single day that I hook up my trailer. In the year that I've had it I have not had to troubleshoot lighting issues especially with your running lights on no issues whatsoever everything runs perfect! don't be like me and buy a bunch of other stuff like additional pigtails trying to fix what someone else has done just buy this system it's worth the money and go for it! I was so confident in this system that I just installed wiring and a hitch on a 2018 Ford Transit t250 and that system is phenomenal too!

1999 Ford Ranger

So to start, I bought this 3 years ago & installed it on my 99 ford ranger after giving up on the pigtails that were previously used as trailer lights. So, the system is designed to either run normal or just stop in the case that something goes haywire in the module. This is what happened in the old system module. Therefore I bought a new one & my trailer lights are running like new again! I figure since I'm pulling a trailer 8 months a year, spending ~$40 every 3 years is not a bad deal. It's easy enough to install, lowet your spare tire. Locate the factory wire harness (usually up behind hitch & behind the bumper) disconnect lights, insert the module with addition of silicone paste, snap together, put it back in general area, route your wire & raise your spare tire. 15 mins max. & done! Super easy!

1996 Ford Ranger

Plug and play. Can't beat it. I bought one of these for my 92 Ford Ranger and one for my 96 Ford Ranger. 2 different part numbers. Simple as unplugging the harness where the bed attaches to the frame at the rear and plug this in between the two plug halves. EZ-PZ. I have used etrailer before and i will use them again if i need to.

1994 Ford Ranger

Very easy to install tried all the lights everything worked perfect very pleased with this product IF I add a trailer hitch to another vehicle I will use this type of connection no more splicing wires and taping them up GREAT PRODUCT

1994 Ford Ranger

Worked great, and just a couple minutes to install!

Ford Ranger

Quick easy install on Ranger pickup. Everything fit.

by: 06/10/2022

Great product. This is easier to install before the hitch.


Perfect fit

Still working great
Roy - 02/16/2022


easy to fit in electrical harness on my truck and seems plenty long enough for my use.


Perfect fit

1996 Ford Ranger

I installed this on a 1996 Ranger. I removed the rearmost bumper mounting bolt on each side and then loosened the other two. This allowed the bumper to drop down far enough to easily access the wiring. At that point you unplug the factor harness and plug in the trailer wiring. I drilled one hole behind the license plate to hold the wiring harness in place and the installation was complete.

No problems. Easy installation.
Tom N - 05/28/2015

Mazda B2300-Series-Pickup

Product arrived on-time and thanks to the helpful instructions, I was able to install this wiring harness in a matter of minutes. My son is out using the truck w/trailer to mow lawns or I would take a picture of the installed harness. I am very satisfied with the product.

After one year, and many trailer tows, the harness is still working perfectly.
Ray F - 09/02/2017


We bought aTekonsha custom fit vehicle wiring for wiring up the trailer and it was perfect. Wiring a trailer has never been so easy, we made a great choice. etrailer is very good to work with and they deliver fast. I wouldn't hesitate to use them again.

Good as when we first put it on. Never a problem with it, very happy
L K - 07/07/2020


Plugged right into my 1994 Ford Ranger wiring harness and worked great. I use my trailer all the time and it is still working great!

1994 Ford Ranger

Product was as described. It plugged right into the original harness everything thing is great. I went cheap on shipping and still had the harness in 4 days. I will not go anywhere else for trailer parts. Awesome job

It still works just like it did when I installed it.
Scott - 11/29/2016

1997 Ford Ranger

I was able to install the part that I bought on my truck, but I didn't realize that the 4-pole flat output doesn't have a wire for a brake light, and I need a wire for a brake light. Do you have any suggestions for a supplementary/replacement part that I could buy from you guys that would include a wire for a brake light? I have a 1997 Ford Ranger, and the T portion of the product that I bought works just fine - the only issue is that the brake light wire is lost somehow in the conversion.

This wiring harness includes a taillight converter, which takes the brake lamp and turn signal signals and combines them onto one circuit. Many vehicles use whats called a separate taillight system, with separate bulbs for turn signals and brake lamps. Most trailers, however use the more simple combined system that carries both signals on the same circuit.
-- Etrailer Expert Mike L - 02/27/2019

1994 Ford Ranger

Awesome hitch wiring for my ford ranger. I only had to unplug current wiring and plug in this adaptor and that was all. I would like to let everyone know that if your ford ranger (mine is 1994) needs wiring harness for a hitch this is the exact fit and is still working 1 year later.

1999 Ford Ranger

Couldn't be happier with the wiring harness. It plugged directly into the wiring harness on the truck and had enough length to route it along the frame and secure it with wire ties in several places. The converter came with self-stick adhesive which made mounting a breeze, although I also secured it with a small bolt through the mounting hole on the converter. During the installation, I used 1/2 inch plastic ribbed wire conduit to protect the wiring harness from chaffing, although it is not necessary. I installed it on a 1999 Ford Ranger, which has separate turn signal lamps from the tail/brake lamps. If you have a similar vehicle, I highly recommend this product. Also shipping was extremely fast.

2010 Ford Ranger

I ordered a trailer wiring harness for my Ford Ranger. It arrived several days earlier than scheduled, which is always appreciated! Installation was very easy, took only about 10 minutes. It plugged right into the factory wiring harness. A quick check with the voltmeter to verify everything works, which it does, and I'm ready to tow! Thanks e-trailer!

1994 Ford Ranger

Great product thus far. The installation was simple (the connector is right above the back of the bumper), and between the supplied zip tie and the adhesive backing on the plastic box, it was easy to mount securely to the back of the bumper mount structure. Now I just need to figure out how to securely and cleanly hide away the wiring while it's not in use.

The whole experience with etrailer has been great so far, btw. Everything I ordered shipped in sturdy boxes, was well packaged, and shipped quickly.

1993 Ford Ranger

This product fit the factory wiring harness as advertised. Made adding the trailer wiring connection very simple without creating new problems in the vehicles wiring harness. I would buy this product again if I needed to add trailer wiring to another vehicle.

1993 Ford Ranger

the product was as described, fit well no problems, needs a better way to attach connector to bumper. still plug and play.

still satisfied with the product, no problems.
phillip - 09/14/2016


I'll tell ya what, this made wiring for my trailer a no-brainer. I found the connection on the rear underside of my truck, separated, and inserted the wiring harness, and i was off and running! (just had to make sure everything was secure).

thanks guys, custom harness makes this easy for someone who is not so truck or wire savvy.

Show More Reviews

See what our Experts say about this Tekonsha Custom Fit Vehicle Wiring

  • Trailer Right Turn Signal Does Not Work When Connected to 3 Different Vehicles
    It certainly does sound like a short on the trailer that caused some problems, but I would not rule out the possibility that it is just coincidence and that there is an issue with all the vehicles in some way, shape, or form. If the trailer draws more that 2.1 amps per side for turn/brake lights then that would cause the converter to blow. On the trailer, make sure its connector is free of corrosion. Then you will want to trace the wiring leading back from the 4-Way to determine if there...
    view full answer...
  • Trailer Wiring Harness Recommendation and Functions for a 1993 Ford Ranger
    On a vehicle that has turn signals that are separate from the brake lights, a converter, # 118325 in this case, is required. The converter takes the separate signals on the vehicle and combines them to turn/brake lights on the same circuit which is what trailers use. Your trailer has what is called a wishbone harness. Normally, yellow is the driver side and green is the passenger side. When there is 2 brown wires this means that the running light signal is split at the connector so you...
    view full answer...
  • Installing 4-Way Trailer Connector on 1994 Ford Ranger
    It is extremely easy to install a 4-way on your 1994 Ford Ranger, and I have added a cut out as well as a link to the instructions of the one that fits your truck, the T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # 118325. All you have to do is find the harness inside your Ranger's left frame rail and plug the connector in and you're done.
    view full answer...
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  • Ford Ranger Trailer Wiring Recommendation
    The recommended trailer wiring harness for your 1997 Ford Ranger is the Tow Ready # 118325. As long as you don't exceed the amperage ratings of the wiring (Stop/turn lights: 2.1 amps per circuit and Tail lights: 4 amps per circuit), you would be just fine.
    view full answer...
  • Trailer Wiring Harness Recommendation for a 1996 Ford Ranger
    For your 1996 Ford Ranger you would need a trailer wiring harness like the part # 118325 that has a turn signal converter wired into it. It sounds like you tried wiring a 4-way directly to your vehicle wiring and it isn't functioning correctly. The # 118325 would be what you need.
    view full answer...
  • Are Trailer Turn Signals Working Opposite of 1997 Ford Ranger Turn Signals with Brake Pressed Normal
    There is nothing wrong with the installation of the T-One Vehicle Wiring Harness # 118325 on your 1997 Ford Ranger. Your trailer lights working opposite of your Ranger turn signals when you press the brake pedal is actually pretty common.
    view full answer...
  • Diagnosing Faulty Trailer Wiring Harness on a 1993 Ford Ranger
    The issue you described sounds like a bad ground but could also be attributed to a faulty converter box or corrosion. I would first check the grounds. The best way to do this would be to remove each of them on both the trailer connectors and the lighting assemblies. I recommend sanding down the surface with some sandpaper and then attaching with new hardware. If the issue still persists once the grounds have been checked then it would also be worthwhile to look inside the trailer connectors...
    view full answer...
  • Blown Trailer Light Relay on a 1993 Ford Ranger
    I am a little confused by what you mean. If the factory relay located in the fuse box on your 1993 Ford Ranger has burnt up when the trailer wiring was connected then you have a short in one of the circuits. In order to fix this you would need to trace each wire back as far as possible while checking for breaks in the wire and repairing as needed. If you are referring to the converter box that attaches in between the trailer connector and port on the vehicle then the solution is the same...
    view full answer...
  • Trailer Wiring Harness for a 1993 Ford Ranger
    The separate brake lights and turn signals on your 1993 Ford Ranger is called a 3-wire or separate system. These systems require a converter, which is not uncommon, to make them compatible with the 2-wire or combined system used by trailers. The wiring harnesses for your Ranger have converters built in. You can use # 118325 which will tee in line with the truck's tail light wiring. I have included a link to the instructions for you.
    view full answer...
  • 4-Way Trailer Wiring Recommendation for 1993 Ford Ranger
    Sounds like you are thinking about hardwiring a 4-way to your 1993 Ford Ranger. Before you do so you should know that you won't be able to successfully pull that off due to the vehicle wiring design of your Ranger. It has separate turn signals from stop lights so you have to use a harness with a converter built into it like the part # 118325 that you referenced which is a confirmed fit. 4-Way Trailer wiring combines the blinkers and stoplights and that's why taillight wiring like what...
    view full answer...
  • Troubleshooting Wire Harness Short Circuit on a T-One Trailer Wiring Harness with Converter
    It sounds like the converter on the T-One Wiring Harness, item # 118325, is shorted. There are many reasons which could cause the converter to go bad. Most often connecting to a trailer that has a short in the wiring is the cause. The only solution in this case is to replace the wiring harness and then making sure the wiring on any trailer you may be towing is correct.
    view full answer...
  • Tail Lights and/or Brake Lights On and Use Turn Signal One side Brightens-Other Side Light Goes Dim
    It sounds like you have one of two problems. Either the wiring on the 1995 Ford Ranger is not converted as it should be to allow the brake and turn signals to work on the same circuit correctly, or there is a ground issue on the trailer that is showing up when the brakes and turn signals are applied at the same time. If your trailer wiring does not have an inline converter, like the black box on the # 118325 T-One Harness, then you will need to purchase one and install it. The #118325...
    view full answer...
  • Troubleshooting a Shorted Out T-One Vehicle Wiring Harness # 118325 on a 1996 Ford Ranger
    It sounds like the # 118325 might be bad since you checked the voltage before the unit and there was power but after there is not. However, since this is the second one of these you have gone through it sounds like you might have a short somewhere on the trailer that is causing the # 118325 to short out and quit working. I would recommend you go over your trailer wiring and check for any bad grounds, loose wires or corrosion and fix as necessary. I attached installation instructions...
    view full answer...
  • Why Would a Trailer Wiring Harness Not Have Power at the Connector
    If you have a # 118325 installed on your Ford Ranger and it does not have power ran to it then your truck's taillights would also not be working. That would typically indicate a blown fuse under the hood of the truck. If you have a different style of trailer wiring harness most likely you have a blown trailer wiring fuse. I attached a help article on troubleshooting trailer wiring harnesses for you to check out as well.
    view full answer...
  • Troubleshooting Trailer Turn Signal and Brake Lights Not Working On 2004 Ford Ranger Factory 4-Way
    The fuses for the trailer turn signals on your 2004 Ford Ranger are in the engine compartment fuse panel. They are 7.5amp fuses at locations 38 and 42. It is strange that they separated the fuse for the trailer running lights as it is in the passenger compartment fuse box at location 2. It has a 10 amp rating.
    view full answer...
  • Repairing T-One Vehicle Wiring Harness # 118325 for 1999 Ford Ranger
    I would first start by testing the wires on the T-connector with a circuit tester like the Quickee, # 3808, to make sure that each is functioning as it should. If there is an issue with any of the wires, you will need to replace the T-One Vehicle Wiring Harness, # 118325. If all functions are working, you can use the Upgraded Taillight Converter, # 119130, to complete your wiring harness. The wires on this converter will just need to be connect to the wires on the T-connector, color for color.
    view full answer...
  • Using Trailer Lights on a 1997 Ford Ranger with Separate Turn Signals and Brake Lights
    The 1997 Ford Ranger has separate turn signals and brake lights. Trailer lights have combined brake lights and turn signals. What you will need to do is use trailer wiring harness # 118325 which plugs into the factory tail light connectors on the truck (or if those are gone you can cut off the end that plugs into the vehicle and hard wire it in). If you have to cut off the end that plugs into the vehicle tail light connectors then hardwire it as follows: brown connects to vehicle running...
    view full answer...
  • How to Install a 4-Way Trailer Connector on a 1994 Ford Ranger Truck
    If your 1994 Ford Ranger does not currently have any trailer connector, the simplest way to install a 4-Way plug would be to use custom plug-in wiring harness # 118325. This harness would be installed at the factory connector that is located underneath the rear of the vehicle, along the inside of the left rear frame rail. I have included a link to the instructions below, if needed. The # 37185 adapter would convert an existing 4-Way plug to a 7-Way. If you need to adapt to a 7-Way plug,...
    view full answer...
  • Troubleshooting Broken Ground Pin on Trailer Wiring Harness for a 1994 Ford Ranger
    The only wiring harness we carry for the 1994 Ford Ranger is the T-One Vehicle Wiring Harness, # 118325, that you have referenced. The black converter box does contain some electrical components that could potentially go bad. But if you are consistently having a trouble with the same wiring harness, it may be a symptom of another problem. You did mention the ground post breaking off. This could occur if there is corrosion build up in either connector, making it difficult to connect and...
    view full answer...
  • Does the Curt Hitch Interfere with my Spare tire on my 1999 Ford Ranger?
    No the curt is a great fit. Your spare tire will fit right back in its original position after installing the Curt Trailer Hitch Receiver Class III part # 13138 . I have included a photo of it installed for you to reference hoe it fit with the spare. If you plan on pulling a trailer and don't have wiring yet the Tekonsha T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector part # 118325 is designed to work with your Ranger and doesn't require you to cut or splice any of your...
    view full answer...
  • Troubleshooting Trailer Brakes that Lock Up After Installing 4-Way to 7-Way
    Did the trailer ever have a 6-way installed on it? There are two common ways that 6-ways get wired and the only difference is that the 12 volt and the brake output circuits are swapped and this causes what you described. But the good news is that all you need to do currently is swap the two circuits and the brakes will stop locking up.
    view full answer...
  • Trailer Hitch Recommendation for 1996 Ford Ranger Splash
    For your 1996 Ford Ranger Splash the Draw Tite hitch part # 75082 is the best option as it has more than needed towing capacity, is mostly hidden, and installs easily. I attached an install video for this for you to check out as well. If you need trailer wiring too the Tekonsha kit part # 118325 is very easy to install and very reliable.
    view full answer...
  • Recommended Class III Trailer Hitch for 1993 Ford Ranger with Full Size Spare
    For your 1993 Ford Ranger XLT, I recommend the Curt Trailer Hitch Receiver # 13138. This Class III hitch is confirmed to fit your truck and will fit along with the full size spare tire under the vehicle. The hitch has a towing weight capacity of 4,000 pounds and a tongue weight capacity of 400 pounds. Just note that some drilling will be required during installation. I have attached the written installation instructions and a video on the 1999 Ford Ranger that you can use for reference. If...
    view full answer...
    Image 1 for
  • Where Does an LED Tailgate Light Bar Wire Up on a 1997 Chevy C/K Series Truck
    Those wires that you have found might be correct to use for a tailgate light bar but to be sure you would have to test them with a circuit tester such as # 40376. The easiest option would be to install a 4-Way trailer connector, # 118325, that will just plug in line with the main tail light wiring harness in the truck and provide a 4-Way flat trailer connector. I have included a link to a video showing how it installs.
    view full answer...
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