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  2. Tekonsha
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  5. 4 Flat
  6. Powered Converter
T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

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

Item # 118578
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Custom Fit Vehicle Wiring 118578 - 4 Flat - 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. Powered ModuLite reduces strain on wiring system. Call 800-298-8924 to order Tekonsha custom fit vehicle wiring part number 118578 or order online at etrailer.com. 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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Tekonsha Custom Fit Vehicle Wiring - 118578

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

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.


Features:

  • 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
    • Locate connection points in trunk
    • Plug in T-connector
    • Run hot lead to car battery
  • Includes ModuLite to ensure that your vehicle'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


Specs:

  • Maximum amperage:
    • Stop/turn lights: 5 amps per circuit
    • Tail lights: 7.5 amps per circuit
  • 1-Year limited warranty


Installation

This custom-fit T-One connector plugs into your vehicle's wiring harness, which is located inside your trunk, behind the tail lights on both the driver's side and passenger's side. You will need to remove some interior trim or carpeting to access the harness. 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 in an out-of-the-way location within your trunk.


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 vehicle'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 vehicle operate.


With a ModuLite, your trailer's lights will be powered without overloading your vehicle'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.



118578 Tow Ready T-1 T-Connector - 4 Wire - Modu-Lite

Installation Details 118578 Installation instructions

This Product Fits The Following Vehicles



California residents: click here


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 Tow Ready Trailer Wiring Harness Installation - 2018 Toyota RAV4

Speaker 1: Today on this 2018 Toyota RAV4 we'll be having a look at and showing how to install the Tekonsha T-One vehicle wiring harness with a four-pole flat trailer connector, part number 118578. Here's what our wiring looks like installed. As you can see, when it's not in use we can easily store it in our spare tire compartment. When we want to use it, we can just take the wire out. We'll drape it over our rear bumper here, making sure we don't pinch it in our latch, and we can close our hatch.As you'll notice, our wire is long enough to easily reach down next to the receiver on our hitch. This makes it easy for us to hook up to our trailer.

Now the reason you're going to want a wiring harness such as this one is so you can safely and legally tow your trailer. You'll have all the necessary lighting functions that are required by law in order to do so. This green wire here provides your right turn signal and right brake light. The yellow wire provides your left turn signal and left brake light. The brown wire provides your taillight and running light signal.

This white wire here provides the necessary ground connection between your RAV4 and your trailer in order for the lights to work properly.One thing that I really like about this wiring harness is that it does have a separate module box, which isolates your RAV4's expensive lighting components and electrical circuitry from any potential short circuits that may occur in your trailer from damaging the vehicle. We have a nice dust cover that's built in to protect our connector when it's not in use.Now this wiring harness provides five amps of power output per side for our turn signals and brake lights, which is more than sufficient to tow a small trailer with a few incandescent light bulbs or several LED light bulbs because they do draw less power. On our taillight circuit on this brown wire, we have a total power output of seven and a half amps. We could run several incandescent light bulbs for running lights and taillights without an issue and basically as many LED as we want.Now one thing that our customers really like about this wiring is how they can store it inside their vehicle when it's not in use and it's out of the way and protected from the elements. Others have said that they really like how it's plug and play and they don't have to splice any wires on their vehicle at all.

Just goes right inline with their factory taillight connectors, which won't void the warranty on your vehicle when you're installing this.Now that we've gone over some features, we'll show you how to get it installed. To begin our install, we'll start by opening our rear hatch. Now we'll start by removing all of our floor coverings, including our spare tire. Now we can get these side panels out here. The way it's attached on the driver side, we have two plastic push pin fasteners to remove.

Use a trim panel to go underneath it and pry up and it'll come out. Now we can lift up on the entire panel and set it. Now we can remove our threshold. The way this comes out, you just lift up on it and release it from the clips underneath. We'll remove the styrofoam that our spare tire rests in as well.We're looking at our driver side interior panel, the lower panel. We have a Phillips screw right here and we have a 10mm bolt here that holds our cargo tie down point in place. We want to remove both of these fasteners. Now we're going to pull back on our interior panel here to gain access to our wiring behind it. Use my trim panel tool to help pry away on the side of the vehicle.Now that we have our panel loose at the back, we have a couple more fasteners to remove so we can get it further loose closer to the front. We'll have a 10mm fastener here that we'll remove. At this forward cargo point we'll fold it down, fold down the cover. We'll find a 14mm fastener that we have to remove. We also found there's one more fastener behind this plastic plug here. We'll use a small flat head screwdriver, pry the cover open. Inside we'll find a 10mm fastener. With that fastener out, we can now pull our panel apart enough so we can pull this panel loose now. I'll pry behind it.Behind the white panel, near the bottom of it, we find this white connector here. That is for our driver side taillight. We're going to unclip that connector now and bring it out so it's easier to work with. Now on the connector there's this tab. Press in on the tab and then pull to separate the two connectors.Now that we've gained access to our driver side connector, we'll repeat the same process on the passenger side in order to gain access to that connector. We're back on the driver side now. We'll take our t-connector here with the yellow wire. We'll match up the female end on our t-connector to the male end of the vehicle. We'll push until it clicks into place. Now we'll take the other end and go to the other part of the wiring harness.Now we'll take our connector with the green wire and we'll bring this over to the passenger side, where we'll make our connections. I'll put the male end in the female end on the wiring harness and we'll grab the other wire and plug it in as well. Now I'll put our wire connectors back into place. We'll repeat the same process over on the passenger side. Now we'll tuck our wires behind our panel here. Now we'll snap our panels back into place. Now we'll take the black wire that comes off of our module box here. We'll strip off a little insulation from it, take one of the yellow butt connectors that comes with our kit, place it over the wire, and we'll crimp it into place. Now we'll take one end of the roll of black wire that comes with our kit, strip off some insulation, and we'll stick that into the other end of the butt connector and we'll crimp that in place as well.We went ahead and wrapped our butt connector and down our wire a little bit with some electrical tape. This'll help better protect our connector from any corrosion or dirt and debris getting inside. We'll do that on every butt connection features point forward. Now on the backside of our module we'll apply our double-sided tape. We'll peel back the other side and we'll stick this down in this spot here on our driver side panel underneath it. We'll push down firmly and this will hold it in place. Now our white wire with our ring terminal on it, that's our ground. We'll need to attach this to our vehicle's sheet metal with the provided self-tapping screw.Now there's a couple grommets in our floor. The one that's closest to our driver side, we're going to drill a hole right through the middle of it. We'll take the other end of our black wire, go underneath this carpet here, and then pass through the hole that we just drilled in the grommet. We'll just keep doing this until all the wire's pulled through. Once you have enough sticking out, you can pull the wire up through the bottom and it does go through a lot faster.Now we'll take some black silicone, which we have available on our website, and we'll go around the hole that we drilled in the grommet. This will just help keep any moisture, dirt, or debris from entering the vehicle. Also keep out exhaust fumes. Now we'll reinstall all of our fasteners, cargo tie down hooks, and floor coverings.When we reinstall this driver side panel, want to make sure our four-pole flat will go underneath it. Here's the grommet where our power wire comes out underneath the vehicle. We went ahead and routed this power wire towards the front of the vehicle, making sure we avoided any moving parts and sources of heat. We went over our rear subframe. We have it zip tied to a wiring harness there. Comes down. We have it zip tied to our parking brake cable here on this outer sleeve right next to this bracket. This section doesn't move so we're fine. Goes alongside our fuel tank here. We went over our filler neck and it comes down here, zip tied to our evap vent line here. Goes underneath this plastic panel where it comes out. Then we have it zip tied to an empty spot in this bracket for fuel lines. It comes out over our plastic panel here just behind our front subframe. We dropped down a pull wire so we can pull up our wire from down below into our engine compartment.We zip tied our wire to the vacuum hose that goes to our brake booster. This will keep it away from any of our steering components. We wrapped it around our air box and we have it zip tied to our battery cable here. This is perfect because this is where we need to start making our connections. Now we'll cut off our excess wire. We'll strip back some insulation, take our remaining butt connector, stick it on the wire, and we'll crimp it into place. Take our fuse holder here. It's one continuous loop of wire right now so we'll cut it in the middle, thus giving us two ends. Strip back insulation from both ends. On one end we'll crimp on our ring terminal that comes with the kit. On the other end we'll place on our butt connector that we installed on the black wire. We put some electrical tape over that butt connector. Now we'll remove the cover over the positive terminal on our battery, where we'll expose a nut. We'll remove this nut. It's a 12mm. We'll place our ring terminal over that stud and reinstall the nut. We can replace the cover over our battery post. Now we'll install our fuse in the fuse holder and close the dust cover over it.Now we'll test our wiring, make sure it works properly. We're using a four-pole flat tester which we have on our website. It's part number I26. You could also hook up to your trailer and test it that way. Start by turning on our headlights. As you can see, our taillight and running light function's working. Do a left turn signal now. That's working as well. Try our right. That's working. Check our brake lights. Brake lights are working. While our foot's on the brake, we'll double check and make sure both of our turn signals still work properly. Perfect. Everything's working as intended. That completes our look at and showing how to install the Tekonsha T-One vehicle wiring harness with a four-pole flat trailer connector, part number 118578, on this 2018 Toyota RAV4.


Customer Reviews

T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector - 118578

Average Customer Rating:  4.8 out of 5 stars   (290 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.

- 118578
by:

Installation is not near as easy as they make it look in the video. Be prepared to spend some time on this getting the connections released from the factory connecter will really wear your patience 735370



- 118578
by:

The materials and instructions are sound. I installed it myself. My advice is that if you don’t own a torque wrench and don’t have thick hide then hire somebody else to do this for you. Not worth the struggle. 645282



- 118578
by:
2013 Toyota RAV4

If you're comfortable pulling panels and routing wires, install is a snap. It is a plug and play solution that removes the need for custom wiring and works perfectly. 613639



- 118578
by:
2015 Toyota RAV4

This wiring kit was everything they said that it was. Plugged right in (when I finally got to the harness) and it works great. I didn't like leaving the flat 4 connector stored inside, so I ran it down through a rubber plug that was already there so that it is out where I need it all the time. Thanks. 430821


Comments
I have used it a lot and it is working perfect.
Steve - 09/10/2018

43418

- 118578
by:
2015 Toyota RAV4

The best part is that it connects into the existing lighting system with electrical T-connectors. The worst part for me was running the power wire underneath the vehicle up to the battery. Other than that everything went perfectly, and the video on the website was extremely helpful. I'm a novice, and it took me about 2 hours to complete the job from start to finish. 573950



- 118578
by:

I selected this unit because e-trailer has such a good video about installing one. However I found in real life that the video missed several good hints, and became quite vague when it came to the more difficult steps. But that is also true for the printed instructions that come with the kit. First, go spend the ten bucks at your local auto store for a good tool to pop out the panel fasteners. 1. On the " right side the tail light connectors, the "catch" that holds the connectors together is hidden. To see how they work, check the matching connectors on your unit. 2. The wire bundle between the right and left side is too short. There is no flat area on the right side large enough to mount the control module. I just wrapped the control module in some foam, taped it with duct tape, and left it loose (but still behind the left rear panel) . 3. Getting under my vehicle to route the power wire on a creeper is impossible. But the instructions offered the alternate of running it inside the body. So that's what I did. BUT, getting it through the bulkhead turned out to be a major problem. (I, and my son, spent most of an afternoon just on that item alone.) Seriously think about whether you have the the ability to do this job before you purchase. These problems are not unique to this brand, and you will run into these same problems regardless which unit you buy. 131043



- 118578
by:
2016 Toyota RAV4

Product is as advertised and works well. I was able to do this install myself, watching the video on the etrailer website. The video was key for me! Without this video, I would not have tried to take on this job. As it turns out, it wasn't that bad. Taking my time, I was able to do this install in about 60 mins. The only comment I might add is to list the tools needed for the job. Wire cutters, strippers, crimper, sockets etc.. I did not have a crimper and had to improvise with vice grips. 421340



- 118578
by:
2003 Infiniti FX45

Installation of the hitch was fairly easy. I used the box as my assistant to hold up the hitch while I bolted it on. As others have stated the holes don't line up perfectly from side to side but with a bit of maneuvering I was able to get the bolts in. Installing the light wiring kit was a bit harder. Removing and reinstalling the panels was easier than I expected. (Although I got a few cuts and my hands and arms) The hardest part was running the wire up front to the battery. As I don't have a car lift in my garage getting under the vehicle was challenging. I did jack up one side and that helped. I went up the center and followed other wiring. I was able to route the tail through the jack storage box and it makes a good storage place for the cable as well. The best part was saving about $200 over a business install and about $800 over a dealer install. 243262



- 118578
by:
2016 Toyota RAV4

For many years, I've installed my own trailer wiring with a test probe and scotch connectors. I was going to re-use one of my old "passive" harnesses but my mechanic warned me that newer cars are more sensitive to the current load and I should use a "powered" unit made specifically for my 2016 Rav4. That led me to the 118578 T-One wiring harness. I won't say installation was a breeze, but the T connectors certainly simplify the job. The included instructions are not the greatest, but etrailer's video is very helpful in showing which interior panels to remove, and how to do it. It's tight quarters, but by starting on the drivers side, you can see how the factory plugs disconnect. When you get to the passenger side, the plug will be facing away from you and is really hard to disconnect, even when you know how it works. What I eventually did was to detach the plug from the pillar so I could turn it around and get better access. This part of the installation, and attaching the ground went fairly easily, The time consuming part is running the hot lead to the battery. The instructions say to run it under the car. That would be fairly straightforward, but I'm not comfortable with that. It's probably fine, but I live on dirt roads and the underside is prone to bottoming out in mud and snow. I read of folks running the wire inside the car, so that's the route I took. Getting the wire to the front was simple....certainly no more difficult than jacking the vehicle and laying under it. I was able to thread the wire under the side panels in the back. The door sills pull up easily by hand, and then you can push the wire through the door post covers. The hard part was getting through the firewall. The wiring bundle for the entire car runs through one hole under the dash on the drivers side. There is one huge rubber grommet and the bundle runs through the center. There is a hole in the side of the grommet that looks like it was made to accept an extra wire, but it has to be punctured for the wire to pass through. When the wire comes out the other side in the engine compartment, it's in a totally inaccessible (and barely visible) spot. I had to make a lot of attempts before the end of the wire finally protruded somewhere I could grab it. After that, connecting to the battery was simple. Now that it's done, I'm glad I installed the battery wire inside. I have yet to pull my trailer with this kit, so I can't speak to reliability. As for the installation, this kit made installation as easy as it can get. 400826



- 118578
by:
2018 Toyota RAV4

Easy to install. Came with all the parts and instructions. Video on eTrailer website was super helpful! 682884



- 118578
by:
2017 Toyota RAV4

I think that the product overall is good. But, I don't think putting this Assy. together is for novices. The video was helpful but, I improved on the safety and more professional installation. One thing I have a problem with is running the hot wire over the sub frame of the car. This is how the video shows the installation. The first time you go to your tire dealer for tires he probably will place his lift support guess where? On top of the hot wire you ran over the sub frame. Guess what happens then - Electrical short! I drilled an additional hole (in the sub frame) and then ran the wire through a piece of rubber hose for protection. Also, an electrical plug mount is welded on the hitch. Why not use it rather than slamming your trunk on the plug wire? Such an armature set up. 545604


Comments
It is working out fine. I only use my Rav 4 for pulling small light trailer. I think that my pictures show a quality professional job. I was a machinist for many years and can make custom parts that I needed.
John D - 07/24/2019

58164

- 118578
by:
2017 Toyota RAV4

Installed in a 2017 RAV4 by a (as defined by the government) elderly person (over 65). The good: Almost everything necessary comes in the box (extras obtained at another store); all connectors snapped together as they should; and all panels/trim pieces came loose without breaking, then popped back into place so one cannot tell they were ever apart. The bad: Those extra parts needed (probably my fault as I installed inside as suggested by another reviewer rather than underneath) The ugly: My hands (one looks like I've been attacked by a small animal) and arms will take several days to recover from being scraped and stabbed by the rear side panels (there was some blood to be wiped off one) and their retaining pins and it took 3 half days to complete (some of that spent "pondering" and taking that trip to another store). First, I appreciate the video posted by etrailer showing the installation. I do however wish a little more time was spent on making the connections behind the panels in the back. (Reminded me a bit of my high school geometry class where the proof was left to the student.) Second, I spent some time "pondering" whether to do an outside hot wire run from the back up to the battery or inside, under the trim panels on the passenger side and through the firewall. In the old days there would have been plenty of places to zip tie this wire along the outside underneath. However, with all of the plastic panels (I'm told for aerodynamics), without taking them down, I didn't really see a clear path from back to front. Other reviewers have posted about the ease of running the wire down the inside on the passenger side - only removing a couple of trim pieces necessary - with the hardest part getting through the firewall. I elected the inside routing once I figured out how to get through the firewall (see "fourth", below). Third, at this point, I pulled the back cargo area apart, i.e., took out the jack, the across the rear panel, the two rearmost side bottom black panels, and the panel in front of the spare. (not necessary to take out the spare) This gave me some idea of what I'd be dealing with once I got the hot wire routed. Fourth, I took off the quarter round trim at the side of the passenger foot well (just pops off), the trim behind the glove box (a couple of little tabs near the glove box hinge & it drops down - retained by those tabs and a couple of protrusions, one at the firewall and one at the right), and the side "kick" panel at the side of the passenger footwell (pops off after removing a square plastic coated nut, about the middle of the panel). After some pondering and looking around I discovered a large rubber boot in the firewall behind electrical junction boxes on the outside passenger footwell. It is hidden underneath insulation so look for where the large cable bundle and what is, I think, a fluid hose for the rear wiper, penetrate the firewall. On the engine side, this boot is behind the shock tower. You can sorta see it but most of the work was by feel. This boot has a thin rubber nipple protruding on the engine side, on the fender side of the boot. I cut the end off this nipple with a small pair of side-cutters. I then fed the wire through that nipple from the engine side. Takes some pushing but it will come through on the inside. I then routed the wire along the engine side of the firewall, then along the driver side fender to the battery. Once I had sufficient wire in the engine compartment, I pulled the excess into the passenger footwell. (Be sure to leave enough in the engine compartment so you can zip tie it out of the way. Installer's choice as far as routing. There are plenty of cables to zip tie to.) Fifth, the relatively easy part of getting the wire to the back. I did find an old wire shirt hanger in the closet which I cut up to use to fish the wire through the wire race behind the plastic at the door pillar. The quarter round plastic in the back seat popped off easily. I then stuffed the wire in the small gap between the rear forward plastic trim piece and the carpet, did the same in the rear compartment, then routed through the metal "tunnel"/beam in the very rear to get it to the passenger side to hook to the black wire in the harness. This is where I spliced in about 1.5 feet of automotive wire from another store with the butt-splice connectors (the red ones work just fine), also from another store. Sixth, the rear cargo compartment side panels come loose pretty much as shown in the video. As the trim retainers let go with quite a pop/snap it is a bit disconcerting as it sounds like something is breaking. The real downside is, while the wire connector is exactly where it is shown to be in the video, it is very difficult to lay hands/fingers on. Getting those connectors to come apart was the hardest, most difficult part of the job, although after the fact, looking at them, they should have easily come apart. I was finally able to use a long, flat-blade screwdriver to pry them loose from the metal panel. Once I'd done that getting them apart and the appropriate limb of the towing harness "spliced in" was literally a snap. The connectors only go together one way and, if you'd broken one of the retainers when you pried it loose with the screwdriver, there is the same connector with the same retainer on the harness limb. Seventh, mounted the controller box to the outside (sorta facing the spare tire at about a 45 degree to the forward/aft vehicle centerline) of that open box beam which runs across the back. Used the mounting tape and a screw. Also, when mounting the grounding wire, I did use my Dremel with a little grinding wheel to get to bare metal under the end loop. Figured it couldn't hurt to get as good of a ground as I could. I also piloted the screws even though they were self tapping as i thought it would just made things easier. Eighth, made the connection of the hot wire to the battery. This bit was straight forward and went exactly as the instructions/video said it would. Yes, I left the fuse out until ALL connections made. Ninth, I'd seen a tester for a flat trailer connecter at another store. Bought for, as I recall, $3.99. Used it to test the connector before I buttoned everything back up. Tested all good. Final comments: Actually not all that hard, just a lot of "pondering", working blind, and some poking and scraping of the hide. The extras cost me, probably $10 - $12. I'd recommend a crimping tool/wire stripper tool if you don't have one, also available at another store for around $5. (I had two so did not need another.) After watching the video, I thought I could do it, bought the part, then just kept plugging away at it. 473348


Comments
Used the set-up to plug in a Thule Transporter Combi for a trip from SE AZ cross country to the Boston area in April 2017. Worked just fine but have not used it since. Transporter is hung from the garage ceiling waiting for the next adventure.
SteveO - 01/05/2019

48254

- 118578
by:
2017 Toyota RAV4

Really heavy duty, weighs almost 40 pounds. Instaltion a snap (watched the video a bunch of times first). Took less than 45 minutes and that is including time needed to get all tools ready. A online hint of using the box it came in to support it while attaching it to the frame was extremely helpful! Fit perfectly, looks great. Now I'm ready to attempt the wiring harness. Have seen the videos but wish they had one without the battery in the trunk. I foresee the hardest part finding a way to get the hot wire to the battery under the hood. 374607


Comments
Haven’t used for towing yet.
Bobbobs - 04/26/2018

37750

- 118578
by:
2017 Toyota RAV4

Product was delivered as scheduled and the quality exceeded my expectations. I watched the online installation video several times and that made the installation much easier. Also, I purchased a set of auto trim panel removers that made the panel removal easy and safe. It took me about 2 hours to install the wiring harness. When I hooked it up to my trailer, it didn't work at first. I checked all of the connections and discovered that I had crimped the connector that goes to the battery accessory post incorrectly. I made the repair and it now works well. Would buy the product again. 432115


Comments
Works fine!
Jim S - 09/13/2018

43595

- 118578
by:
2015 Toyota RAV4

My car was a little difficult because of where my tail light connectors are, lots of trim panels to remove to access stuff. Plug and play though. I ran my power wire under the vehicle because it was easier... I zip tied it to the brake lines and stuff like that. 655696



- 118578
by:
Toyota RAV4

Kit was installed with little issue. I ran the power lead inside my RAV4, up the driver side of the car under the sill panels, and through the large rubber "penetrator" under the dash into the engine compartment. I used a short tube made from a thin ball-point pen to "puncture" rubber. I then used some stiff wire to snake into the engine compartment - it comes up just behind the struct pillar, so some fiddling is required to get it so it can be pulled forward. I then used the wire to pull the power cable through. I also cut the 4-wire lead about 1' from the converter, and threaded it through the large grommet just to the left of the spare, and thne added conectors to to the leads inside. This got the flat wire outside the vehicle permanently, just inches from the hitch. A little RTV sealed up the grommet nicely. Only complaint is that passenger side wire could be a few inches longer for a cleaner install - the convertor box didn't mountin the best of spots due to the short lead. 124272



- 118578
by:
2015 Toyota RAV4

The 76134 receiver is well made. All weld beads are continuous and consistent and the material is sized right for adequate strength and minimum weight. Mounting bolt hole pattern is right on. Paint is good and consistent with no dings or scratches. Installation was straight forward. It was necessary to procure a M12 X 1.25 tap to run through the mounting weld nuts in the frame in order to get the bolts to thread in; not a fault of the receiver but the effects of four years of over the road use of the 2015 RAV4. Also the small amount of extra money for this hidden crossbar version of a receiver was worth it when looking at the final installation. The 118578 T-One harness kit installation was also straight forward and it works as it should. Installation was made a little less difficult with the use of the ALL648544 trim pad remover that was purchased with this order. 647642



- 118578
by:
2014 Toyota RAV4

My products: 118578 wiring harness for 2014 RAV4 C13149 trailer hitch for 2014 RAV4 The hitch was a breeze to install. I didn't even need to drop the exhaust. I used a bottle jack to support one side just high enough so I could get one bolt started, moved to the other side and inserted the 2 bolts and the rest is history. The wiring harness is another story due to the requirement to disassemble the rear interior trim panels. I assumed the first connector I found was it. It did not match the connector on the harness. I called for help and spoke with Cathy T. and she got me on the right track. The connectors are located about chest high, the ones I mistakenly chose are mounted near the floor. All went well other than getting my forearms a bit bloodied by the sharp edges of the plastic trim panels. etrailet.com saved me approximately $615.00, the dealer wanted $835.00 to install a hitch and wiring harness. 133378



- 118578
by:
2015 Toyota RAV4

I`ll start by saying watch the installation video.If you decide you want to tackle this, follow the advice of another reviewer and get the panel removal tool,I`m glad I did! I found this product to be excellent quality with plenty of wire to reach both sides on my RAV4.The connectors are a pain to uncouple,the factory wiring has no slack so make sure you know where the release tabs are .I routed the black hot wire inside the vehicle and went through the firewall where the factory wiring goes.My advice on this project is watch the installation video carefully and allow yourself plenty of time.My trailer lights work perfectly and my trim panels look like they have never been touched.My thanks goes to other reviewers for their helpful input! 225942


Comments
I`m very pleased with the Tekonsha wiring kit for my 2015 RAV4.Everything works every time I need to use my trailersI have several! I highly recommend etrailer for fast,reliable and courteous service!
Dennis M - 09/21/2016

21131

- 118578
by:

Great products with good quality. Trailer hitch is well hidden under car, so not real noticeable. Safety lock and pin are nice. 743395



- 118578
by:
2015 Toyota RAV4

Works fine, no problems, had local garage install it for me. 737015



- 118578
by:
Toyota

Great product, works just as described. Electrical clips fit perfect on the exsisting wiring of my 2015 toyota rav 4. I have used this product for months now and I am happy with my purchase. Great value. 736732



- 118578
by:

Took 25 minutes to install. Just enter the part number in YouTube and a great how-to video pops up. Great price, quick shipping, and easy to install. Would definitely buy again. 736386



- 118578
by:
Saturn Relay

This electronic relay was great! Couldn't figure out why the factory installed 7 pin socket would not power my RV trailer lights. Then I realized my Mercedes GL 450 SUV had LED lights and the trailer incandescent lights. Installing your kit,118578, converted the low voltage/amperage to the correct power to operate my incandescent trailer lights! This kit solved my problem, was easy to install with the great instructions and economical. I am now a happy camper. I also bought a similar kit from you for my RAV 4 to haul my boat trailer. I addition I bought the blue tooth brake controller from you and it works great. It help to avoid a lot of wiring and the driver side control box. Thank you! 735285



- 118578
by:

I ran the wire inside so the installation took longer since I had to remove several trim panels to run the wire under. I used the hood latch cable to fish the wire thru the firewall - like a found in another post. 734956


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Ask the Experts about this Tekonsha Custom Fit Vehicle Wiring

  • Recommended Wiring Kit for Towing with a 2017 Toyota RAV4
    Out of the Curt # C56350, Tekonsha T-One # 118578, and Hopkins # HM11141820 wiring harness kits for your 2017 Toyota RAV4 Hybrid I highly recommend going with the T-One option. The reason being that we have found the Tekonsha electronic equipment to last longer and work better than many other brands. The installation is fairly simple and only requires you to plug in the T adapters behind the tail lights, grounding a wire, and then run a hot lead up to the battery. I have attached a...
    view full answer...
  • Vehicle Wiring Harness With 4-Pole Flat For RAV4 Hybrid
    I reached out to my contact at Tekonsha and they confirmed that the T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # 118578 will fit the 2018 Toyota RAV4 Hybrid. The complete install video on the 2018 Toyota RAV4 is attached to this page.
    view full answer...
  • Recommended Trailer Wiring Harness For 2017 Toyota RAV4
    For your 2017 Toyota RAV4, I recommend the Tekonsha T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # 118578. This custom-fit T-One connector plugs into your Toyota RAV4's wiring harness, which is located inside your trunk, behind the tail lights on both the driver's side and passenger's side. You will need to remove some interior trim or carpeting to access the harness. Once you've plugged in the T-connector, run the hot lead up to your car battery. Connect the lead...
    view full answer...
  • Trailer Wiring Recommendation for 2018 Toyota RAV4 Hybrid
    Yes, we do have trailer wiring that fits your 2018 Toyota RAV4 hybrid. For that I recommend the Tekonsha kit part # 118578 because it installs without requiring any hardwiring and because it has the most reliable converter box of all of the kits we offer. I attached an install video for this for you to check out as well.
    view full answer...
  • How to Route Power Wire from T-One to Battery on a 2018 Toyota RAV4
    The best route to run wiring from the back to the front of a vehicle, like the T-One # 118578 on your 2018 Toyota RAV4, is to keep it away from moving parts and run it through the frame when possible for best protection. We actually have an installation video of this being done on a 2018 RAV4 for you to check out. You can mount it in the cargo area if you would like or you can try to find a grommet in the cargo area of your RAV4 and route the 4-Way connector through it so that you can...
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  • Recommended Trailer Wiring Harness for 2018 Toyota RAV4
    For your 2018 Toyota RAV4 I recommend the Tekonsha T-One Vehicle Wiring Harness # 118578. This custom harness will plug right into factory ports behind the trim panels in the cargo area of your RAV4 to provide you with a 4-Way connector to power a trailer's basic signal lights. I recommend this particular harness because it features a higher maximum amperage for its circuits than the alternatives. We also get far fewer troubleshooting questions regarding Tekonsha harnesses than we do with...
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  • Installing Power Wire for Tekonsha T-One Harness # 118578 on 2018 Toyota RAV4 Hybrid
    I spoke with my contact at Tekonsha regarding the T-One Vehicle Wiring Harness # 118578 (which is confirmed to fit your Hybrid model RAV4). He said that you will definitely want to connect the power wire to the positive post of the battery at the back of your vehicle. There aren't any specific or alternative instructions with regards to this process but you just want to route the wire back, making sure to avoid any hot areas or spots where the wire might get pinched. You will need to remove...
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  • Does Power Wire of Trailer Wiring for 2018 Toyota RAV4 Drain Battery When Not in Use
    Since the wire to the battery does not draw any amperage when the vehicle is off and a trailer is not connected it would not drain it. It's the same principle as the wiring of your vehicle that already runs to the battery. When those circuits aren't active it does not drain it at all.
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  • 2016 RAV4 Hybrid Trailer Wiring Harness Fit
    Tow Ready has confirmed for us that their trailer wiring harness # 118578 will fit and would work well. I attached a picture that points out which terminal to use on the battery for running the power wier of the harness. I attached an install video for you to check out as well.
    view full answer...
  • Where to Connect Power Wire of Tow Ready 118578 Trailer Wiring Harness on 2016 Toyota RAV4 Hybrid
    The terminal you have the power wire connected to looks like it's a fused terminal. I'd recommend connecting to the bolt that's closest to the positive battery post as shown in the photo I've edited for you. This will provide you with a direct connection to the battery. Tow Ready confirms that the # 118578 is compatible with your 2016 Toyota RAV4 Hybrid.
    view full answer...
  • 4-Way Trailer Wiring Harness Recommendation for 2017 Toyota RAV4
    Since your trailer does not have brakes and only weighs 1,000 lbs the type of trailer wiring kit you'd need would be a 4-way harness. Basically the 4-way is for just providing the taillight circuits to the trailer. For that the best option is the Tekonsha kit part # 118578 which is a confirmed custom-fit. I attached an install video for more info as well. The Tekonsha brand of trailer wiring is the most reliable option we have so it's the one we recommend the highest.
    view full answer...
  • Does T-One Wiring Harness Need Power For Trailer Lights To Function
    Your 2014 RAV4 has what is called separate wiring which means the brake and turn signals are run on different wires. A trailer runs on a 2-wire system where the brake and turn signals are on one wire. The module that is included with the # 118578 wiring harness takes the separate signals from the vehicle and combines them so they will work with the trailer wiring. It does not affect how the light work on the vehicle. The converter has a hot lead wire that needs to be connected to the...
    view full answer...
  • Best Trailer Wiring Harness for 2018 Toyota RAV4
    The wiring harness I recommend for your 2018 Toyota RAV4 is the T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # 118578 because it is easy to install on your RAV4; you will only need to plug it into connection points in your rear cargo area and run a hot lead to your battery. Additionally, you can have faith in how dependable this harness is because its manufacturer, Tekonsha, has a very strong reputation for creating quality wiring products. As such, this harness also...
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  • Does Battery Need to be Disconnected to Install Tow Ready Trailer Wiring on a 2015 Toyota RAV4
    Step 11 of the trailer wiring harness part # 118578 that you referenced indicates that you have to disconnect the negative post of your vehicle's battery temporarily. You would lose some radio presets doing this but nothing permanent would get damaged. On the other hand, if you were to leave the battery connected there is a chance you COULD damage the electric system or get shocked yourself. I attached an install video for you to check out as well.
    view full answer...
  • Recommended Trailer Wiring Harness for 2017 Toyota RAV4
    It sounds like you might be looking for a trailer wiring harness for your 2017 Toyota RAV4. For this, I recommend the Tekonsha T-One Vehicle Wiring Harness # 118578. This harness is custom-fit for your RAV4 and will connect directly to the built-in ports behind the trim panels in the cargo area of your vehicle. Once installed, this will give you a 4-Way connector at the rear of the RAV4 to connect with and power your trailer's signal lights. I have attached the written installation details...
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  • Does the Power Wire of the Tow Ready 4-Way Harness # 118578 Have to Run to Vehicle Battery
    If you were to run the power wire of the Tow Ready Custom Fit Vehicle Wiring # 118578 to anywhere but the positive post of your vehicle battery you would void the warranty of the harness and could potentially damage the wiring of your RAV4 in the event of a short on the trailer wiring. The purpose of the battery wire being run to the battery is so that it bypasses the delicate vehicle wiring and eliminates the potential threat of the trailer wiring damaging the vehicle's wiring. It draws...
    view full answer...
  • Correct 4-Pole Wiring Harness for 2014 Toyota RAV4
    To add a 4-way connector to your 2014 Toyota RAV4 I recommend the T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # 118578. This is a plug-in harness so you can avoid splicing; I've added a link to an install of this harness on a '14 RAV4 as well as a link to a video review of the harness for you to take a look at.
    view full answer...
  • What Size Fuse Goes in Fuse Holder of Trailer Wiring Kit for 2016 Toyota RAV4
    The fuse that installs in the yellow fuse holder of the Tekonsha trailer wiring kit part # 118578 that you referenced for your 2016 Toyota RAV4 is 15 amp. I attached an install video for this kit on a similar RAV4 as yours for you to check out as well.
    view full answer...
  • Does Wiring Harness # 118252 Fit 2017 Toyota Rav4 LE?
    The T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # 118578 is the confirmed fit for the 2017 Toyota RAV4. This custom-fit T-One connector plugs into your Toyota RAV4's wiring harness, which is located inside your trunk, behind the tail lights on both the driver's side and passenger's side. You will need to remove some interior trim or carpeting to access the harness. Once you've plugged in the T-connector, run the hot lead up to your car battery. Connect the lead to...
    view full answer...
  • Trailer Wiring Harness for a 2016 Toyota RAV4 with LED Tail Lights
    All you will need is the proper wiring harness for your 2016 Toyota RAV4 and it will work just fine with the vehicle's LED tail lights. Trailer wiring harness # 118578 is a great option. I have included a link to a video showing an example installation for you.
    view full answer...
  • Parts Needed to Install 7-Way Wiring Harness on 2015 Toyota RAV4
    The Draw Tite hitch part # 75235 that you are interested in for your 2015 Toyota RAV4 is a great choice for a trailer hitch. I attached an install video for it as well. For wiring you would need the part # 118578 to give you a 4-way and then would need the part # 37185 to convert it to a 7-way. From there you would need to run a 10 gauge wire like part # 10-1-1 up to the positive post of the battery through a circuit breaker like part # 9510. Since you wanted to do some towing you...
    view full answer...
  • Can Power Wire of 2018 Toyota RAV4 Hybrid be Ran to Rear Battery
    Yes, when you install the Tekonsha trailer wiring kit part # 118578 on your 2018 Toyota RAV4 Hybrid you can run the power wire to the battery in the rear of the vehicle which would be easier than running to the front of the vehicle.
    view full answer...
  • My 2014 Toyota RAV4 T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector
    To determine if the problem is on the 2014 Toyota RAV4 or on the trailer there are some tests you can do. First, disconnect the trailer for the RAV4. Then use a circuit tester such as # 40376 to test the vehicle side connector while someone sits in the vehicle and operates the light functions. If you do not get power on the connector while testing then the issue is on the vehicle side. Make sure that the harness white ground wire is attached to a clean metal surface. No paint or coating...
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  • Wiring Harness 118578 Installation in 2016 Toyota RAV4
    In most modern trailer and vehicle wiring the ground wire color used is typically white. This is indeed true for installing the Tekonsha 4-pole wiring harness # 118578 in your RAV4. Often this white ground wire will have a ring terminal which can help us sort out its function. The black 12V power wire does indeed connect to the battery + terminal through the included fuse holder. For reference, I linked the written instructions and a video showing this wiring kit installed in a 2018...
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  • Brake Controller and Wiring Recommendation for 2015 Toyota RAV4
    For installing wiring and a brake controller in your 2015 Toyota RAV4 you will need to start with a 4-way (if you do not have one). For that you would want the # 118578. I attachd an install video for this for you to check out as well. From there you would need to convert the 4-way to a 7-way so that you can install the brake controller. For that you will want the Brake Controller Install Kit and 7-Way Adapter part # ETBC7. I attached installation instructions and an install video for...
    view full answer...
  • Hot Lead Wiring, Fuse, and Fuse Holder to Complete Trailer Wiring Harness for 2011 Jeep Liberty
    We have exactly what you need! For the black wiring that goes to the battery on your 2011 Jeep Liberty (12 gauge) and the required 10 amp fuse and fuse holder, all you need is the Modulite Installation Wiring Kit # 118151. This kit includes the those components along with 8 cable ties, a couple of ring terminals and a butt connector for installation.
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  • Why Is Separate 12V Battery Power Connection Required for Wiring Harness 118578
    Thank you for your purchase of Tekonsha 4-pole wiring harness # 118578 for your 2016 Toyota RAV4. You ask a reasonable question about the installation of this item. It is not recommended to use a vehicle's auxiliary 12V power outlet to power a trailer wiring harness like Tekonsha # 118578. The reason is that doing so takes away the main advantage of using a powered converter, which is to isolate and protect the vehicle's wiring from any potential damage from a short or other fault on...
    view full answer...

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Info for this part was:

Expert Research:
Mike L
Expert Research:
Michael H
Expert Research:
Jameson C
Expert Research:
Adam R
Expert Research:
Jeffrey L
Video Edited:
Joshua S
Video Edited:
Jacob T
Video Edited:
Dustin K
Video Edited:
Chris R
Test Fit:
Nicholas E
Test Fit:
Randy B
Test Fit:
Brent H
Video by:
Kathleen M
Updated by:
Laura H
Updated by:
Sarah W
Updated by:
Alexander C
Updated by:
Isabelle B
Installed by:
Cole B

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