Arrives before Christmas To see if this custom-fit item will work for you please tell us what vehicle you'll use it with.
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Tired of complicated trailer wiring setups? The T-One Vehicle Wiring Harness from Tekonsha is your solution. Designed for a perfect custom fit, this harness plugs directly into your vehicle's existing wiring, making it a breeze to install with no hardwiring needed. Simply find the connection points in your rear cargo area, plug in the T-connector, and you're set. It's as simple as plug and play, saving you time and eliminating the hassle.
Prevent electrical overloads with the built-in ModuLite power converter. This smart feature ensures your vehicle's wiring system matches that of your trailer by combining brake and turn signals onto one wire. It pulls power directly from your car’s battery, which means there's virtually no strain on your vehicle’s electrical circuits. This thoughtful design keeps your vehicle's factory wires untouched while powering your trailer's lights safely and efficiently.
Whether you’re towing a small utility trailer or a multi-axle trailer, this wiring harness can handle it. Equipped with a 4-way flat trailer connector, it’s compatible with 5-pole, 6-pole, and 7-pole adapters (sold separately). This versatility means you can easily adapt your wiring to match various trailer types and configurations, making it a must-have for all your towing needs.
Keep your trailer connections clean and secure with the 4-way flat connector’s durable dust cap. It also comes with 16-gauge bonded wire, constructed to withstand harsh weather conditions and resist corrosion over time. This robust design means you can tow with confidence, knowing your connections are protected from the elements.
This wiring harness is tailored specifically to fit a wide range of vehicles, including Mercedes-Benz Sprinter Vans. It’s been engineered to easily integrate with factory wiring setups, ensuring that installation is straightforward. Whether your van’s already fitted out or a standard model, this harness fits seamlessly, giving you complete peace of mind.
Built to last with high-quality materials, this wiring harness ensures reliable functionality for your trailer lights. It supports up to 5 amps per circuit for stop/turn lights and 7.5 amps per circuit for tail lights while including safety measures like an inline fuse holder. This combination of reliability and protection guarantees that you’re always ready to hit the road safely.
This custom-fit T-One connector plugs into your vehicle's wiring harness, which is located inside your rear cargo area, behind the tail lights on both the driver's side and passenger's side. You will need to remove some interior paneling to access this 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 your 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.
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.
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.
This will not affect how the tail lights on your vehicle operate.
California residents: click here
I installed this device per instructions and followed the video step by step. The device tested out as operating. I did not have need to use the device right away. A few months passed and my opportunity came to use the device. When I connected with it it did not work. I tested all the connections and it was clear the device had failed. Thankfully is was still within the 12 month warranty. I contacted etrailer for warranty exchange, no problem except the replacement device was on back order. I was told it would be delivered in 27 days. Almost three months later the replacement device arrived. Over that period of time I needed the use of trailer lights several times, summer camping and boating trips. Now that summer is over and my trailering opportunities have passed. I will once again install the device and wait for a future opportunity or need for its use. I have serious doubts that it will be operational when I need it or that it will have any reasonable lifespan of functional use. If there was any other option I would use it. Good luck
Install was fairly straight forward and simple but it had given me miscellaneous issues with turn signals not working. Some days there are no issues some days there are. When the module is unplugged I have zero issues. Overall nice product though
I installed it tested and it works great
The positive black wire is a couple fit short
But a previously ordered 6 ft of 16-1-1 cable
It's thinner than in the harness but it can be used, so I added
The installer on video had enough cable because it's a shorter Van.
You may not see to much on pictures because
I fished the wire to the passenger side inside around door frame
On both tail lights on pictures is no wires !
they All inside
Would recommend this to a friend
Solid build as I would expect from DrawTite. Installation was easy. Needed to buy additional bolts ($95) because Sprinter Factory bolts were removed by previous owner.
The kit was confirmed for my vehicle by the sales rep. I had the bulk of the kit installed. The final step of installation is the power wire to the battery. The power wire is several feet too short. The customer service rep suggested i go to Home Depot to purchase additional materials needed to complete the installation. What?! I opted to uninstall and wait 3 days for additional wire from etrailer. I'm certain this is not the first time. Please correct your kit or warn customers that it is incomplete prior to purchase. VERY disappointed.
Bought for my 2008 Dodge Sprinter LWB van and was easy to install by following directions to the letter. Works as it should and am perfectly happy as it was a good deal price-wise as well. Bought a hitch here also and would give it the same review. Thanks.
Dudley P.
5/30/2021
Still working great and have had absolutely no problems. Thanks again for a product that was easy to install and does the job it was designed to do well.
The product does not work as stated. It was easy to instal, it did connect to wiring harness and there was enough wire to do the job. But the power pack that came with it doesn't have enough power to run all the lights causing the van to constantly thinks the lights are out. Also the light don't work half of the time because of this. It has been worked on many time and the problem has not be fixed.
Mike L.
7/7/2018
There are a couple of possible causes for the problem youre experiencing. Some vehicles have bulb-out sensors that cause the taillights on the vehicle and trailer to hyperflash when its sensed that a bulb is out. If the trailer has LED lamps that only draw a fraction of the current of incandescents, the sensor reads the low power draw as a bulb out and the trailer lamps wont work properly. Another possibility is that the converter is overloaded as you suggested. If the trailer has more lamps than the normal stop/turn/running lamp and a few marker lamps, and the bulbs are incandescent, the draw could be exceeding the 5 amp/circuit stop and turn and 7.5 amp taillight circuit capacity of the converter. Ive linked to a help article that explains how to troubleshoot a trailer wiring harness.
Helpful Links
Wasn't sure what to get, customer service was excellent helping me choose. The whole kit worked great and had everything I needed. Awesome videos of how to install in my 2012 Sprinter. I always recommend e-trailer as first choice to other colleagues and friends. Thanks guys!
Ruel
11/6/2023
I installed this kit about 2 yrs ago. It has been great, forgot all about it! E-Trailers videos and instructions were very good. I have a 170 base 2013 Sprinter.
This is on a custom kit to add trailer wiring to a Sprinter van.
The kit had everything I needed to do the job. I might have had to supply a few of my own zipties but I don't recall at this point.
Easy to install for an experienced mechanic with some electrical knowledge. Might be borderline difficult for average do-it-yourselfers. The final result was perfect.
One thing I had to cover on my own is this kit requires a power wire leading all the way to the battery. That wire a about 3 feet short. I spliced in an extension and all was good but....... In the manufacturers defense our Sprinter is a long and tall version so it would have the longest run to the battery of all these models. But still the kit is said to fit all and 3-4 feet more wire is only pennies.
Used this trailer wire loom on my 2007 Sprinter van. Very complete kit, had plenty of wire length and all the connectors fit where they were supposed to. Saved me many hours of measuring, splicing, crimping, etc. Be sure to connect the red power wire, on mine I ran a thin-wall plastic tube (drip irrigation tubing works great) as a conduit up to near where the auxiliary frame wiring come through the floor under the drivers seat and connected 12AWG wire to a 12V source.
This product seems to be well made. Being fairly competent I installed it myself in about 6 hours and found the video on your website helpful. Regarding Video: I found that; feeding the trailer connection plug wire down under the bumper cover tricky and required loosening the cover further; The running of power cable underneath worked easiest(I opted to drill a small hole in the upper side of the battery box.) and that it might not be long enough to run up and down the inside.
Also for me removing the taillights with out braking the plastic side pins/clips difficult having not had to do it before. I would recommend watching other installation videos [online] for more tips/ideas on ways to run wires etc..
Plugged right in to my 2011 170 sprinter. You just have to find a power source and the rest is plug to plug. Perfect for those of us without factory trailer wiring. It was tough to fish from drivers side to passenger side and I found it easier to cut the plug off and resplice once down the passenger side pillar.
Wiring harness was malfunctioning right out of the box now I have to buy a different one
Brooke M.
4/29/2025
Oh my - that's not what we want to hear! Let me look into this for you - we will be in touch!
My hitch and wiring harnesses arrived sooner than I expected in generally good shape. the hitch was chipped around the receiver which will happen anyway but you always want new stuff you buy to be perfect. I installed the hitch already and don't expect anything out of the ordinary on the wiring. I purchased wiring and the brake controller earlier on and all went well so I assume it will on my van as well.
Everything fit my sprinter van perfectly. I tend to be skeptical of things I order, but this product exceeded all expectations. Quality appears to be great, and the instructions were very clear, not at all like the instructions you often get with products these days that were obviously written by someone for whom English is clearly not their native language. I found an excellent etrailer youtube video that showed an alternate way to install the wiring which turned out to be a better option for my situation because my sprinter van is already fitted out and it would have been a problem to try to run the wires overhead and interior the way the written instructions suggested.
The harness was fairly easy to work with. I took one additional step to keep the flat 4 pin outside the van. I did this by removing the black rubber rear entry threshold and drilling a hole thru the metal floor underneath. I ran the wiring through the hole and replaced the threshold and bypassed shutting the doors on wires when using a trailer.
The kit had everything needed. I watched the excellent installation video on line several times. This made the process stress-free.
The product arrived quickly and in good condition.
The components are of high quality. They fit exactly right, clicking into position as advertised.
The only minor quibble: the black wire that goes to the battery was about 18 inches too short. I have the longest version of a Sprinter van, so that might have been the problem. No worries. I spliced in some additional wire, problem solved.
easy install , just watch etrailer video and they walk you through it . I installed the 4 way trailer kit on a 2010 m.b. sprinter 2500 and there was everything you needed in the kit . save yourself money and do it yourself .
This trailer wiring harness for my 2007 Dodge Sprinter works perfectly! It was super easy to install, and works completely without any issues. I'm so glad I ordered this one!
The part was broken. Once we got a chance to get it installed and found out it was broken it was to late to return it with free shipping. Now I must pay to return it under the warranty.
Good Product.
Arrived on date promissed/
Very easy to install.
Only thing is the power cable is not long enough for a 170 in wheelbase Sprinter if you want to run the wiring inside. Need to buy extension.
Hitch installation was super easy. Everything fit perfect and if you follow the instructions it is almost effortless. I have not installed the T-one wiring yet as that looks more involved and I haven't had time. But the hitch is great.
This is the place to go to for trailer needs. Everything was done professionally. From updates on order to shipping. Instructions are very clear and easy anyone could do it. Thank you!!!!!!
Easy to install and easy directions to follow. Harness has been in my sprinter van for over a year now and works great still.
First time buyer. Omg how great of a company. Everything u need and then some. Free shipping. And truth be told I had the pleasure of speaking with Terri N when I went to check out. 5 minutes into the phone call,I was thinking to myself what a wonderful person she is. Your company should feel very greatful to have someone like her working for u. I can not began to say it was the best buying experience I have had in a long time. Once again I want to say what a great place and Terri N what a wonderful person. Thank u again
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Brooke M.
4/2/2025
Hey Kevin! This could be as simple as the ground connection has come loose over time. If you want to start there by just making sure you have a secure metal-to-metal connection that's clear of debris paint or rust that might take care of it. I link our troubleshooting guide in the case this doesn't help. You'll want to look at methods 1, 3, 4, and 5, but let me know if the ground takes care of it and we can go from there :)
Helpful Links
faq-4-5-way-troubleshooting.aspx