1. Custom Fit Vehicle Wiring
  2. Tekonsha
  3. Custom Fit
  4. Trailer Hitch Wiring
  5. 4 Flat
  6. No Converter
T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

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

Item # 118451
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Custom Fit Vehicle Wiring

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118451 - No Converter Tekonsha Trailer Hitch Wiring
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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. Call 800-298-8924 to order Tekonsha custom fit vehicle wiring part number 118451 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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  • Reviews (152)
  • Q & A (36)
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  • Why etrailer?

Tekonsha Custom Fit Vehicle Wiring - 118451

  • Custom Fit
  • Trailer Hitch Wiring
  • Tekonsha
  • 4 Flat
  • No 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 - no cutting, splicing or tapping required.


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 - no cutting or splicing of wires
    • Locate connection points behind tail lights
    • Plug in T-connector
  • Constructed of 16-gauge bonded wire
  • Comes with dust cap for 4-way flat connector


Specs:

  • Maximum amperage: 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 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 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.



118451 Tow Ready T-1 T-Connector - 4 Wire

Installation Details 118451 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 - 118451

Average Customer Rating:  4.9 out of 5 stars   (152 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.

- 118451
by:

Excellent service quick and friendly would definitely recommend this company to others 896410



- 118451
by:
2011 GMC Acadia

Great service again thank you 892127



- 118451
by:

Light kit was very simple to install. 871636



- 118451
by:

Great website. Pricing is more than fair. part arrived earlier than stated. Great place to find all things involving trailers ar wiring. 863747



- 118451
by:
2012 GMC Acadia

I purchased this T harness for our GMC Acadia. Installation was easy, and the instructions were thorough. It was a little challenging getting the connectors fished through behind the body panels, but all in all it was an easy job. I definitely recommend this over the cheaper kits with crimp on wire splices. 847533



- 118451
by:

Got my hitch very quickly even with the shipping delays going on with delivery services due to covid-19. As soon as the wiring kit was hooked up all the lights worked on the trailer without having to mess around with it. So far I am loving my purchase and wish I would have gotten one sooner. According to my husband it was a very easy installation for both the wires and the hitch on my GMC Acadia. 824361



- 118451
by:

We returned it and had [equipment company] install one as we were unable to install this one due to rust on the vehicle. No issues with hitch itself. 803852



- 118451
by:

Installed this product on my wife's Acadia so we could tow a U-Haul down to Texas about a year ago. Installation instructions were very clear, and everything fit perfectly. Definitely a 2-man job, and you may also have to ream out some of the threads in the frame holes. Other than that, great product, shipping, and instructions. 795303



- 118451
by:

The wiring kit was spot on for my car was glad I purchased it, it made wiring easy and fast 746463



- 118451
by:

It was easy to wire up and the price was out of reach. But it was had to have ordeals. 729505



- 118451
by:

Looks like it is exactly what I needed. Also, very fast service. 714561



- 118451
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Excellent customer service! 695407



- 118451
by:

High quality! easy installation and the video was really helpful. 678461



- 118451
by:

Perfect product. Install process was simple and quick. 652088



- 118451
by:

This is a high quality made wiring set. The price cannot be beat. Any local trailer store wants much more for a wire harness and it is not a complet ready to go set like this. It makes it so simple to plug into your existing tail lights and it is the perfect length to go from one side to the other and have a little bit extra for tucking and going around corners. I would highly recommed this. 613502



- 118451
by:
GMC Acadia

Product was appropriate for the make and model year of my Acadia. Video instructions were clear and complete. Listen to Danny T. 602664



- 118451
by:

Arrived quickly and installed very easy. 595372



- 118451
by:

Very easy to install took about 20 minutes Works like a charm 568530



- 118451
by:
GMC Acadia

Just got in the mail today, fast shipping. Hope to install next week. Instructions look clear and I know there’s a video on how to install on my GMC Acadia. 552777



- 118451
by:
2007 GMC Acadia

My Vehicle did not come with a tow package, i need lights to my trailer. My Acadia was wired but dead lights coming out of the connector. The T-1 took care of all my problems my trailer is tow ready! The T1 item #118451 is the best solution. I'm very happy with this product. Thank you e.trailer!!! 538830



- 118451
by:
2012 GMC Acadia

Fairly easy to install. Wish it came with additional black ties. I had several on hand otherwise I would have been short. Read the details on your vehicle use of this equipment though. It can get interesting. 525750



- 118451
by:
2010 GMC Acadia

Great service 525199



- 118451
by:
2011 GMC Acadia

Hitch was great for my 2011 Acadia. Customer rep’s advice on electrical wiring package, etc. was invaluable. Hitch came in 2 days. I will definitely be ordering from them again. 506328



- 118451
by:
2011 GMC Acadia

Hitch was great for my 2011 Acadia. Customer rep’s advice on electrical wiring package, etc. was invaluable. Hitch came in 2 days. I will definitely be ordering from them again. 506330



- 118451
by:
2009 GMC Acadia

Great instructions. The video was a perfect step-by-step. Thanks 501846


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Show More Reviews

Ask the Experts about this Tekonsha Custom Fit Vehicle Wiring

  • Troubleshooting Tekonsha T-One Trailer Harness Not Working on 2012 GMC Acadia
    The Tekonsha T-One Wiring Harness # 118451 that you ended up installing is the correct harness for your 2012 GMC Acadia and it will work whether or not you have the tow package so you made the right choice there. If you happen to have your trailer on hand, the first thing I recommend doing is simply hooking it up to the Acadia and plugging in your connectors. Sometimes those LED testers can be a little finicky so it's possible that the harness works perfectly and the tail lights on...
    view full answer...
  • Does a GMC Acadia Need an Upgraded Fuse Panel to Add Trailer Wiring
    What I believe the dealer is suggesting is that if you wanted to add the tow package wiring, you would need that different fuse panel and some other components. This would then give you a 7-Way trailer connector at the back. If you do not want to add the towing package and just need a 4-Way, you can use the T-One Vehicle Wiring Harness, # 118451, without having to upgrade the fuse panel or anything else. This harness was made for those vehicles that do not have the tow package wiring....
    view full answer...
  • Wiring for a 2009 GMC Acadia
    The correct T-One wiring harness for your vehicle is the 118451. Our site lists this harness as being okay for all models – it will work with all LED lights. Please note the tech tip: "Do not splice into the vehicle's wiring system to wire a trailer connector, use only the t-connector that plugs into existing connections." Despite what your dealer indicates, we sell many of the kits, which are then self-installed. I will attach an installation video for your reference below for this...
    view full answer...
  • Trailer Running Lights Will Not Work with 2009 GMC Acadia XLT with Tow Package
    First you are going to want to make sure that the running light circuit is working on the trailer connector on the 2009 GMC Acadia. Use a circuit tester such as # 40376 to test the running light circuit. If it is not working then check the vehicle owners manual for the fuse location for the tow package running lights to check/change it. Also check the owners manual for any relays that might be needed for the tow package wiring. I do not recommend tapping into the running light wire on...
    view full answer...
  • Troubleshooting Wiring on Trailer Towed by 2009 GMC Acadia With Tow Package
    Since you did not find any blown fuses, my suspicion is that the problem lies somewhere in the wiring of the trailer, so lets begin by isolating the problem to confirm that the problem lies in the trailer wiring. Use a circuit tester like part # 40376 on the trailer connector as each lighting function is activated. Activate the right turn signal, then test the pins on the connector. Do the same for the left turn, brake and running lamp. If the trailer connector checks out okay, then...
    view full answer...
  • Difference Between Curt Wiring Harness # C56056 and the Tow Ready T-One Wiring Harness # 118451
    There really is no difference between the Curt T-Connector Wiring Harness, # C56056, and the Tow Ready T-One Wiring Harness, # 118451. They both provide the same function but are manufactured by two different companies.
    view full answer...
  • Installing a Brake Controller on a 2011 GMC Acadia
    If your 2011 GMC Acadia did not come with a factory 7-Way trailer connector then not all of the wiring and parts needed to just plug in a brake controller are present. But you can still hardwire in a brake controller. It sounds like you had a 4-Way to start with and they converted it to a 7-Way. All you will need now is a brake controller and wiring kit # 5506. Using some of the included wire you will need to route the brake controller black and white wires from the vehicle cab,...
    view full answer...
  • Does T-One Harness Part # 118451 for 2008 GMC Acadia need Other Parts due to LED Tail Lights
    I spoke with one of our installers who has installed T-One harness part # 118451 on a 2008 GMC Acadia, and he said you should have no problems. If a T-One harness needs a converter, it will have one built in, but in this case it does not. We also have a video of this part being installed on a 2008 GMC Acadia and I will add a link to it below.
    view full answer...
  • Tail Lights on 2008 GMC Acadia Stop Working when Trailer is Connected
    Let's start with the easy stuff. Make sure the white ground wire on harness # 118451 is attached to a clean bare metal surface on your 2008 GMC Acadia. There can be no coating or paint and it works best if the wire is grounded by itself. If that doesn't help then what is probably going on is the trailer lights draw more power than the vehicle wiring system can handle. You can test this by removing the connections to some of the lights. Then, if everything else starts working, including...
    view full answer...
  • Trailer Wiring Recommendation for a 2014 GMC Acadia
    For a trailer wiring kit confirmed to fit your 2014 GMC Acadia you would want the Tow Ready harness part # 118270. It will not require you to run a power wire up to the battery as it comes with fuses and relays to complete the circuits.
    view full answer...
  • How to Install a Trailer Wiring Harness on a 2011 GMC Acadia
    The plug you are referring to in the photo will not be used to install a trailer connector on your 2011 GMC Acadia. The correct way to install a trailer connector on your Acadia would depend on if you have the factory tow package or not. This is an important distinction to make and in order to be sure you know exactly what you have, you will need to obtain your VIN and contact the manufacturer directly. If you do not have the factory tow package then the connections you will need to...
    view full answer...
  • Troubleshooting Running Lights Not Working On Two Trailers Towed by a 2006 Jeep Commander
    This could definitely be a ground problem. Without a proper ground, the circuit cannot be completed which can cause light failure and/or malfunction. You will also want to make sure you are using the correct wiring harness. For a 2006 Jeep Commander with no factory package, you will need to use Tow Ready Custom Fit Vehicle Wiring, # 118408, instructions linked below. With a tow package, you would use Tow Ready Custom Fit Vehicle Wiring, # 118381. I have included a link to the installation...
    view full answer...
  • Troubleshooting Trailer Brake and Turn Signals Not Working with Tekonsha T-One Harness on Acadia
    The Tekonsha T-One Vehicle Wiring Harness # 118451 that you referenced plugs in-line with the tail light circuits on your GMC Acadia via factory ports behind the tail lights themselves. The harness and the power it receives from your vehicle should be completely separate from any tow package, as it simply gets power from the factory light circuits. There aren't any fuses related to this harness or its ability to send power back to the trailer lights unless the lights on your Acadia aren't...
    view full answer...
  • Troubleshooting No Power On T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # 118451
    I would start checking fuses and relays on the power block in the engine bay. The cover should have a map or listing of all the fuses. Check all of the fuses that have anything to do with tail lights or tow circuits. I have added a link to a wiring FAQ page that shows which pins should serve which function. Use the circuit tester to make sure everything is on the correct pins.
    view full answer...
  • 2009 GMC Acadia LED Turn Signals Operate Erratically After Installing OEM Trailer Wiring
    I have not heard of this issue before on an OEM part installed on a vehicle. Usually if this happens it is on the trailer and is usually a ground problem. I am not sure how the OEM harness installs but if it has its own ground wire then make sure it is attached to a clean bare metal surface. No paint or undercoating can be present. Also, it really should be grounded to its own location and not share a common ground with other electrical devices. It is possible that the trailer lights...
    view full answer...
  • Adding a 5-Way Flat Trailer Connector to a 2012 GMC Acadia
    In order to install a 5-Way flat trailer connector on your 2012 GMC Acadia you will need 2 items. First, since your model does not have the factory tow package, you will start by installing a 4-Way # 118451. With the 4-Way installed you will just need the second item which is a 4- to 5-Way adapter, # 20036. The adapter has an extra wire that will need to be spliced into a reverse light wire. You may be able to find a reverse light wire behind one of the tail lights by probing the wires...
    view full answer...
  • Recommended Wiring For A Trailer With Brakes For A 2011 GMC Acadia
    For your 2011 GMC Acadia, I recommend you start with the T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # 118451. This will give you a 4-way flat as you mentioned. Then you will need the Universal Installation Kit for Trailer Brake Controller # ETBC7. This kit will give you the wire, connectors, and circuit breakers you need to connect a brake controller to a 7-way for a trailer with brakes. For your brake controller, I recommend the Tekonsha Prodigy P3 Trailer Brake...
    view full answer...
  • Trailer Lights do not Work with the Tow Ready T-One Harness # 118451 on a 2010 GMC Acadia
    The Tow Ready T-One Wiring Harness, # 118451, does not require any additional fuses or relays. As you said, this harness provides power to the trailer lights from the vehicles tail light circuits. The only time you would need to install a fuse is if one of the tail light fuses were blown on the vehicle. This would mean your tail lights, turn signals or brake lights were not working on your Acadia. If you are positive that you have a good ground and the T connectors are installed correctly...
    view full answer...
  • No Running Lights With T-One 4-Pole Harness # 118451 on 2009 Acadia XLT with Tow Package
    The wiring harness you referenced, T-One 4-Pole Harness # 118451 from TowReady, uses plug-and-play connections to your Acadia tail light assemblies to generate lighting signals for your trailer. This harness provides trailer lighting signals on its included 4-pole connector that are completely independent of any factory tow package wiring that may be in place. Please take a look at the linked video which shows installation of this harness in your same year/make/model vehicle. The written...
    view full answer...
  • Trailer Lights Malfunction on a Small Utility Trailer Behind a 2009 GMC Acadia with Factory 7-Way
    Vehicles with LEDs will have problems with standard trailers unless a powered tail light harness is used, or there is a factory tow package. If your 7-Way on your Acadia is indeed a factory connector, you should have no problems with LEDs vs. incandescent lights. Most small utility trailers do not have a 7-Way. 7-Ways are used on larger trailers that have electric brakes, or hydraulic systems powered by a battery, or boat trailers with hydraulic actuators with reverse lockouts. If...
    view full answer...
  • Can Bumper Cover be Put Back On 2010 GMC Acadia After Installing Trailer Hitch e98863
    It is highly likely the bumper cover will be able to be put back on your 2010 GMC Acadia after installing the etrailer.com Trailer Hitch Receiver # e98863, though there are some occasions which it has not been able to. That said, it is rare the cover will not go back on, as I went through all of the customer reviews for this hitch and the Curt Trailer Hitch # 13424, and there was just one instance of a customer relaying they were unable to get the cover back on. All other mentions of...
    view full answer...
  • Troubleshooting No Trailer Turn/Brake Signals with 2007 GMC Acadia
    I do agree that the wiring issue you are experiencing is somewhere on your Acadia. You mentioned that the Acadia didn't come with the tow package but it does have the trailer wiring and hitch. This means you likely have a T-Connector wiring harness installed such as the Tekonsha # 118451 that plugs into factory ports behind the tail lights. What I recommend doing is checking the white ground wire coming from the harness. Make sure this is still securely attached to a clean, bare metal...
    view full answer...
  • Parts Needed to Add a 7-Way Trailer Connector to a 2012 GMC Acadia
    The short answer is that wiring harness # 118384 will not fit a 2012 GMC Acadia if it does not have the factory tow package. The harness is meant to plug in line with a factory 7-Way trailer connector. If your vehicle does not have the factory 7-Way then it will not fit. To add a 7-Way you will first need to add a 4-Way, # 118451. Then you can add a 7-Way by using 4 and 7-Way installation kit # ETBC7. I have included a couple of links that explain the ETBC7 installation. If you also...
    view full answer...
  • Trailer Hitch and Wiring Recommendation for 2012 GMC Acadia
    The trailer hitch I recommend for your 2012 GMC Acadia is the Draw-Tite Class III Max Frame Round Tube Receiver # 75528 because it offers a greater towing capacity at an economical price for you. This hitch will also offer a more streamline look for your Acadia when it is exposed than the square and boxier framed Curt hitch. We have found that the original fascia cover on the 2012 models of the Acadia is not able to be reinstalled after an aftermarket hitch is installed. Other customers...
    view full answer...
  • Brake Controller Insatll-2012 GMC Acadia w/ Factory Tow Package
    If your 2012 GMC Acadia was equipped with the factory installed 7-way trailer connector at the rear of the vehicle, then installing a brake controller will be a plug-and-play process. You'll need the # 3026-P brake controller wiring harness, as you mentioned. Other than attaching the controller in its desired mounting location and plugging in the harness, there's nothing else that needs to be done. Install the # TK90160 Primus brake controller under the dash, to the right of the steering...
    view full answer...
  • 4-Way and 7-Way Trailer Connector for 2010 GMC Acadia
    I have a solution for you, and you will not need to cut into any wires. If you do not have a factory tow package on your 2010 GMC Acadia, you will first need to install a 4-way wiring harness. I recommend the Tow Ready T-One Vehicle Wiring Harness # 118451. This wiring harness will plug directly into the back of your taillights, into your vehicle's current wiring system. I have attached an installation video of this harness on a 2011 GMC Acadia. The wiring harness has a 4-way flat...
    view full answer...
  • Trailer Wiring Harness Options for a 2011 GMC Acadia
    The Replacement Multi-Tow 7-Way and 4 Pole Trailer Connector, # 74682, will fit on your 2011 GMC Acadia if it came with a factory installed 7-way trailer connector at the back of the vehicle. There will be a round plug going into the back of your factory 7-way connector that will mate with the round plug from the Multi-Tow harness. If your vehicle did not come with a factory installed 7-way, then you may have the round connector at the rear of your vehicle tucked in the spare tire or...
    view full answer...
  • Trailer Wiring Harness for a 2010 GMC Acadia with or without Factory Tow Package
    I will be happy to help you select the right trailer wiring harness for your 2010 GMC Acadia. Harness # 118270 will not fit though but we do have options that will fit. If that harness you found has a connector on it then what you can do is use a circuit tester such as # 40376 or a meter if you have one and test the pins in that connector. Someone will have to sit in the vehicle and operate the various lighting functions. If it does have power then your Arcadia must have the factory...
    view full answer...
  • Troubleshooting Left Stop/Turn Signals on Trailer Towed by 2007 GMC Acadia
    You have already started the troubleshooting process to find the cause for your trailer's left-side turn and brake lights not working. Since another vehicle has no issue with this trailer this does tend to suggest that the issue is on the Acadia. Since both 4-pole and 7-way trailer wiring setups combined the left stop and turn signals onto one wire, typically a yellow one, what I suggest is that you start a close inspection of this circuit/wire at the trailer connector itself. You can...
    view full answer...
  • How To Install The Draw-Tite Class III Hitch # 75528 On A 2009 GMC Acadia Without Existing Weldnuts
    When installing the Draw-Tite Class III 2 Inch, part # 75528, on a 2009 GMC Acadia, some of the vehicles will not have the weld nuts on the front two mounting holes of the bumper. What you will need to do if you are missing the weld nuts is to use the included handle nuts that will come with the hitch. The handle nuts are used in many trailer hitch installations because of the limited space that is available for installing mounting bolts. The handle nuts are a nut with a handle attached...
    view full answer...

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Info for this part was:

Expert Research:
Mike L
Expert Research:
Patrick B
Expert Research:
Michael H
Expert Research:
Jameson C
Expert Research:
John H
Expert Research:
Adam R
Video Edited:
Zack K
Video Edited:
Joshua S
Video Edited:
Chris R
Updated by:
Laura H
Updated by:
Alexander C
Updated by:
Isabelle B
Installed by:
Cole B

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