The best technical support and full Custom Fit Vehicle Wiring installation instructions. Lowest price Focus Custom Fit Vehicle Wiring guarantee and expert service. Ford Focus, 2012 Custom Fit Vehicle Wiring by Tow Ready are available from For expert service call 800-298-8924 to order your T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector part number 118549, or order online at
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Trailer Wiring > 2012 > Ford > Focus

Tow Ready Custom Fit Vehicle Wiring for the 2012 Focus by Ford

Tow Ready Custom Fit Vehicle Wiring

(17 reviews)

Code:   118549



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T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector - 2012 Focus by Ford

Quickly and easily install a 4-way trailer connector on your Ford Focus with this custom wiring harness. T-One connector plugs directly into existing wiring. Powered ModuLite reduces strain on wiring system.


  • Provides a 4-way flat trailer connector at the back of your Ford Focus to power your trailer's signal lights
    • Compatible with 5-pole, 6-pole and 7-pole adapters (sold separately)
  • Connects quickly and easily
    • Locate connection points behind tail lights
    • Plug in T-connector
    • Run hot lead to car battery
  • Includes ModuLite to ensure that your Ford Focus's wiring matches that of your trailer
    • Powered module connects directly to battery to avoid overloading vehicle's electrical system
  • 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: 5.6 amps per circuit
  • 1-Year limited warranty


This custom-fit T-One connector plugs into your Ford Focus's wiring harness, which is located behind the driver's-side and passenger's-side tail lights. You will have to remove the tail light assemblies to access this harness.

T-One Connection Location Points Behind Tail Lights

Once you've plugged in the T-connector, run the hot lead up to your car battery. Connect the lead to the included fuse holder, and then connect the fuse holder to the positive terminal on your battery and insert the provided fuse.

Once installation is complete, the 4-way flat connector will be stowed within your trunk or rear cargo area.

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.

ModuLite Powered Tail Light Converter

A ModuLite power module 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 Ford Focus's three-wire system need to be combined so they are compatible with the wiring system of your trailer. This power module functions as a tail light converter to combine 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 Ford Focus operate.

With a ModuLite, your trailer's lights will be powered without overloading your Ford Focus's electrical system. Because the module draws power directly from your car's battery and bypasses the electrical routes that are used by a basic wiring harness, there is virtually no draw on your tail light circuits.

118549 Tow Ready T-1 T-Connector - 4 Wire - Modu-Lite

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

Videos are provided as a guide only. Refer to manufacturer
installation instructions and specs for complete information.

Video Transcript for Trailer Wiring Harness Installation - 2012 Ford Focus

Today on our 2012 Ford Focus well be installing Tow Ready T1 connector, part number 118549. Now well begin by opening the tailgate and remove the vehicles taillight housing assemblies. To do this here on the drivers side well remove the black plastic cover and pull back the insulation liner to access the plastic wing nut holding the taillight in place. Theres another wing nut in here that well also need to undo. With both wing nuts undone we can remove the drivers side taillight. Well repeat this process to remove the passenger side assembly.

Were also going to go ahead and remove the rear threshold as well put our wiring harness behind it. Now that we have our interior undone here on the drivers side well need to pass the T1 connector through the vehicle. To do this well cut a slit in our rubber grommet here where the factory wiring harness passes through. We can then feed our T1 connector in and reinstall the rubber grommet. Well now plug our T1 connector into the factory wiring harness.

Youll notice here on the drivers side youll have a white wire with a ring terminal this is the module light ground. Well use the supplied self-tapping screw to run into a body ground connecting our white wire to it. Now with all that done here on the drivers side we can go ahead and reinstall our taillight remembering to plug the other side of our T1 connector into the taillight assembly. Well now route our red and green wire to the passenger side where we can again cut the rubber grommet, pass our T1 connectors through, and reinstall the grommet. After making our connections here on the passenger side we can go ahead and reinstall our taillight.

With that done well need to connect our black wire included with the harness to the module light. Well need to find a suitable location where we can pass the black wire through the body to run it up under the hood. Youll see there are some body plugs here well cut a small slit into the body plug and pass our black wire through it. Well strip the insulation off the black wire as well as the red wire on the module light box. Now using the yellow butt connector, connect the two together.

We can now go ahead and reinstall our interior pieces. Make sure to keep the wiring out of the way of any of the connectors as youre reinstalling. Well now move underneath the vehicle where we can now route our wire up to the battery. Now youll want to make sure you stay away from any moving components such as your suspension or hot components such as your exhaust while routing this wiring. Here at the battery well cut off the access black wire and attach the second of the two yellow butt connectors. Well now take our fuse link, clip it in half and strip back the insulation. Well attach the large yellow ring terminal to one side and the other side well attach the yellow butt connector thats already been attached to the wire. With that done were now ready to connect the yellow ring terminal to the battery. Now there are several ways to do this, were going to go ahead and clip our ring terminal to make it slightly smaller where we can go around the positive terminal post and tighten it down. We can then install our 10 amp fuse included with the harness which will complete the installation of our Tow Ready T1 connector, part number 118549, on our 2012 Ford Focus.

Customer Reviews

T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector - 118549

Average Customer Rating:  4.4 out of 5 stars   (17 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. Powered ModuLite reduces strain on wiring system.

- 118549

by: Michael L.04/22/2015

I installed a trailer hitch on my 2013 Ford Focus so that I could pull my two kayaks on a small trailer. There are two ways to install trailer lighting, either buy a basic harness and splice in the factory harness or you can buy this product and plug and play. I am not excited about tearing in the factory harness as there is no way to go back to the original if you have to or choose to. The way this harness is designed if at some point you decide to remove the wire harness it can be done easily. The installation is pretty easy, the video is very helpful as the instructions are not very clear. The only problem that I experienced is that during the installation you have to cut through the grommets behind each tail light and the connectors are pretty large so it is a little tough pushing the connectors through the grommets. I would recommend that when you add the ground that you remove the paint for the body panel. It might work at first if you don't but over time the ground will stop working and you will be frustrated as to why your trailer lights don't work. One other alteration I made is I wired my power inside the car, I am not saying that the video is wrong, there are more than one way to get the power from the battery to the harness; however, I was not wildly crazy about running power under my car so instead I ran it inside, just my preference. There is a grommet right behind the glove box that you can get through pretty easy, there are video's on youtube to pull power for an amp to the battery . 187279

- 118549

by: larryw07/28/2015

Great products that fit properly. The instructional videos are great. We installed a Draw Tite tow hitch and trailer light hookup on our 2014 Ford Focus. Everything fit properly, and went together just like the video showed. No surprises. 215117

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by: Ashleigh Heinichen05/23/2013

great wireing harness 81713

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by: Spence J.03/31/2015

This must be the fifth or sixth time I have ordered from etrailer and have not been disappointed. One of the best things about etrailer has to be the installation videos. Before my son and I started we watched the hitch and wiring installation videos and even took my tablet to the garage as a reference. Pricing and delivery are more than competitive and because of the support I prefer to give them my business. 182068

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by: Tom H.05/27/2014

Only complaint is that the instructions for a slit in the taillight grommets didn't work that well. The plugs were to big to squeeze through without ripping tho holes even bigger. It would have been easier and keep a better seal if you cut the grommet from the edge to the wires. I did this to run the trailer plug to the mount on the hitch. It isn't ripped and the grommet seals pretty well. 132729

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by: Jimmy Mac11/01/2012

It's a new 2013 Ford Focus and I was not in any rush. The wiring took me about 3½ hours, start to finish. I ran the wire inside the car and had trouble finding a place to exit the firewall so I exited the floor under the clutch, through a grommet and up the firewall to the battery. You need the 12 volts to run the 4 prong trailer plug. Works great 58619

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by: Mark03/17/2015

Easy install overall. I had to grind the heads of the carriage bolts down to make them pass thru the opening of the frame. Also had to grind (or you can cut with a bandsaw) the piece the carriage bolt passes thru to get it to pass into the frame. Would be nice if these pieces came pre-ground/pre-cut to the right size. 179231

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by: Glenn L.08/20/2014

Good product, ran the battery power suppy wiring through the (inside) of the car though, so the wiring isn't exposed to the harsh Minnesota and Wisconsin winters. Wiring install diagram (included with wiring) is a bit vague, and install video makes it look somewhat easier than it really is. 147802

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by: Danny T07/30/2014

I am not a mechanic, but the video makes this installation very easy. This saved me so much time. I couldn't be happier with All of my purchases and installs have gone BETTER than expected. I highly recommend buying this. Traler lights are working great. 143453

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by: David07/11/2013

This product works well and installs very easily. The only difficulty in installing this kit is running the 12V power wire to the battery. I wish the interior design of the car would have been more forgiving, but it wasn't too bad. 88992

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by: Mario09/26/2014

After a few months one of the lights died. Measured voltage with a meter and found to be all over the place. Now a bit over a year later the entire module is dead. Avoid this product! 153293

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by: Dave G.03/28/2014

Great service, Great product, easy to install. Overall I am extremely pleased with and the products I purchased. thank you etrailer 122623

- 118549

by: Martin R08/01/2013

Harder than ever to install the wiring. Running power to battery and removing the lenses took most of the time. Hitch was easy. 92684

- 118549

by: jay r05/29/2015

Videos were very helpful, took a while for a first intstall but mostly because it is a car and all i have is jacks. lol 198573

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by: Sam b06/10/2015

Service was excellent I would definitely recommend this seller for your towing needs. 202183

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by: Kevin P`02/08/2013

Easy quick install 65429

- 118549

by: Mark03/17/2015

Easy enough. 179233


Ask the Experts about this Tow Ready Custom Fit Vehicle Wiring
Do you have a question about this Custom Fit Vehicle Wiring?

  • Trailer Hitch for a 2013 Ford Focus ST Hatchback with Center Exhaust
  • Yes, Curt trailer hitch # C11350 will fit a 2013 Ford Focus ST hatchback with the center exhaust. I have included a picture from the instructions that shows the hitch installed. I have also linked the instructions for you to view. To add a ball mount use # C45521 and pin and clip # PC2. For a 1-7/8 inch ball use # 19256 and for a 2 inch use # 19258. For trailer wiring use # 118549. I have included links to the instructions for the wiring as well. Because the exhaust is in the middle,...
    view full answer...

  • Removing the Tail Lights on a 2012 Ford Focus Hatch Back for Trailer Wiring Installation
  • You will need to remove some trim panels in the rear cargo area of your 2012 Ford Focus in order to gain access to the tail light wiring. If you look at the instructions I have linked for the Curt wiring harness, # C56140, there are some helpful pictures. The tail lights may need to be persuaded slightly because the seals around them can stick. If there are additional fasteners holding on the lights, they may be revealed when you remove the trim panels in the cargo area.
    view full answer...

  • Hitch Recommendation for a 2013 Focus ST Towing a Motorcycle Trailer
  • The Curt Hitch part # C11350 can tow a trailer that weighs up to 2,000 lbs total and exerts a downward force on the hitch of up to 200 lbs. That's what tongue weight is, the vertical force the weight of the trailer puts on the hitch. If the trailer you plan to tow is under those capacities when completely loaded this hitch would work well for you. You also will want to check the owners manual of your 2013 Ford Focus ST to determine how much capacity your vehicle is rated to tow and be...
    view full answer...

  • Recommendations for Running 12V Power Wire on 2012 Ford Focus Trailer Wiring Harness 118549
  • In order to protect your vehicle wiring, it is really best to run the 12V power wire up to the positive battery terminal in the engine compartment of your 2012 Ford Focus. This ensures that you have a direct connection to a 12V source, and that there nothing else pulling power off the same wire. When you tap in at the rear of the vehicle, you run the risk that other functions or accessories have been connected to the same 12V line, which could cause an overload or back feed of power...
    view full answer...

  • Trailer Wiring Harness Options for a 2012 Ford Focus Hatchback
  • There are 2 possible wiring harness options for the 2012 Ford Focus Hatchback. You could use Curt wiring harness, # C56140, that you have referenced. The other option is Tow Ready wiring harness # 118549. I have included links to the instructions for both harnesses. Both harnesses install the same way and require a direct connection to the battery to power the trailer lights. This protects the vehicle electronics. The more popular harness is the Tow ready, # 118549, harness.
    view full answer...

  • Coiled Tow Bar Wiring Extension to Go from a 7-Way to a 4-Way Flat
  • Yes, the tow bar wiring harness # HM56008 will work as a combined system, with the brake lights and turn signals on the same circuits. You could use ta 7-Way to 4-Way adapter either directly in the 7-Way on the RV or at the end of a coiled extension. But I was able to find a nice long coiled cable to go from a 7-Way to a 4-Way, # 787196.
    view full answer...

  • Trailer Wiring Harness for a 2014 Ford Focus ST Hatchback
  • Yes, trailer wiring harness # 118549 will fit your 2014 Ford Focus ST hatchback. I have included a link to the installation instructions and a link to a video showing a typical installation for you.
    view full answer...

  • Towing a Motorcycle Trailer with Separate Brake Lights and Turn Signals with a 2013 Ford Focus
  • The issue is that motorcycles and the trailers made for them usually have separate turn signal and brake light circuits. But on trailers towed by passenger vehicles, the turn signal and brake lights are combined. Basically, you will have to make an adapter. You will need 3 important parts. First you will need a vehicle to vehicle converter # 118158. Next, a trailer side 4-Way, # 18004. And finally a vehicle side 5-Way, # 20016. It will be assembled like in the picture I have provided...
    view full answer...

  • Hitch, Ball Mount, Trailer Ball, and Trailer Wiring Harness for 2014 Ford Focus Hatchback
  • The hitch needed will depend on if your Focus is an ST model. If it is, you'd need the Curt Class I hitch, part # C113503. If it's NOT an ST model, you can use the Curt Class I # C111583, as long as your vehicle isn't an electric model. The hitch includes the drawbar and the pin and clip. Part # 19256 is the recommended 1-7/8 inch trailer ball and part # 118549 is the trailer wiring harness.
    view full answer...

  • Installing a Trailer Wiring Harness on a 2012 Ford Focus
  • It depends on what wiring harness you are using on your 2012 Ford Focus. If you are using a hardwire harness where you have to find and splice in the wires from the harness to the tail light wiring on the vehicle, you will need to use a circuit tester to find the correct wires on the vehicle. If you do not have a circuit tester you can use # 3808. Have someone sit in the vehicle and go through the lighting functions; turn signals, running lights, and brake lights, while you test the...
    view full answer...

  • Using Ford LED Hitch Cover on a 2014 Ford Focus when Flat Towing and When Driving
  • Since you are towing the Focus behind the RV, you would not use wiring harness # 118549 for that purpose. This harness would be used for the Focus to tow a trailer and not to tow the Focus with the motor home. I do understand what you are trying to accomplish though and why you selected that harness; the Ford LED hitch cover # CR-017F has to plug into something! But if you want to use the cover all of the time and not just when flat towing the Focus you will need to have the wiring harness...
    view full answer...

  • Installing LED Tailgate Light Bar on 2014 Ford F250 Using # 118158 Vehicle to Vehicle Converter
  • What you are wanting to use is separate signals from the brake lamp and the turn signals. Using the 118459 would actually get you the opposite of what you're looking for. Use the # 118158 converter, and wire the inputs into the wiring feeding your trailer connector. The converter will separate out the brake signal for you. The orange wire from your light bar would connect to the red output wire from the converter. The green and yellow wires from the light bar would connect to the green...
    view full answer...

  • Hitch and Motorcycle Carrying Options for 2012 Ford Focus Hatchback
  • The hitches that are available for your 2012 Focus Hatchback are all Class I hitches, that have a 200 lb tongue weight capacity. This would mean that 200 lbs is the maximum amount of weight that would be suspended from the hitch, which would include the weight of the carrier. I'm sorry to say that you wouldn't be able to carry your bike on a hitch mounted carrier. This being said, you could still install a hitch like the Hidden Hitch # 60290 and carry your bike on a small utility trailer....
    view full answer...

  • Trailer Wiring Recommendation for a 2013 Ford Focus Hatchback
  • Yes, we do carry trailer wiring for your 2013 Ford Focus Hatchback. You will want the Tow Ready wiring harness part # 118549. I attached an install video for you to check out as well.
    view full answer...

  • Plug and Play Tow Bar Wiring Harness for a 2012 Ford Focus SE Hatchback
  • Trailer wiring harness # 118549 gets the signals it needs through the tail light wiring on your 2012 Ford Focus hatchback. The power for the trailer lights comes from the connection to the vehicle battery. This wiring harness is if the Focus is towing a trailer and will not work in reverse (towing the Focus behind a motor home). For a similar harness that is set up to work as tow bar wiring and that plugs inline with the tail light wiring use # HM56008. The harness gets its power from...
    view full answer...

  • Recommendation for Way to Transport Mobility Scooter with 2012 Ford Focus Hatchback
  • You are correct that a Class I hitch receiver is the only hitch available for your 2012 Ford Focus. When it comes to transporting a mobility scooter with your Focus, I recommend using the Draw-Tite Trailer Hitch, # 24872, to tow a small trailer like the Magneta with Spring Axle for Wheelchairs and Electric Scooters, # UWT1. To complete the towing set-up you will need a drawbar with pin and clip like the Sportframe Kit, # 3593, 2" Hitch Ball, # 19258, and T-One Vehicle Wiring Harness,...
    view full answer...

  • Would Performing a Battery Test Fry a Trailer Wiring Harness on a 2012 Ford Focus
  • If the yellow fuse holder wire from wiring harness # 118549 was pulled out at the battery then it would not have done anything to the converter box. What might have happened is some part of the system when attached to the battery touched something else and melted or burned something but that is speculation. The trailer lights get the power from that connection to the battery so if it is not connected or the fuse is blown then it will not work. If it is all connected and the lights are...
    view full answer...

Do you have a question about this Custom Fit Vehicle Wiring?

Info for this part was:

Photos by:
Theodore B

Expert Research:
Michael L

Video Edited:
Zack K

Expert Research:
Sarah L

Video by:
Andrew K

Expert Research:
Michael H

Test Fit:
Nicholas E

Video Edited:
Andrew L

Updated by:
Laura H

Test Fit:
Shane T

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