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Hopkins Endurance 4-Way Flat Trailer Wiring Harness - 20' Long

Hopkins Endurance 4-Way Flat Trailer Wiring Harness - 20' Long

Item # HM48240
Our Price: $33.70
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Trailer Wiring
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Shipping Weight: 0.87 lbs
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Wishbone-style Y-harness features a 4-pole flat connector with a convenient, simple-to-use, easy-pull grip for effortless disconnect. Rust-resistant terminals are further protected by a molded dust cover, and all wires are color coded. Great Prices for the best trailer wiring from Hopkins. Hopkins Endurance 4-Way Flat Trailer Wiring Harness - 20' Long part number HM48240 can be ordered online at or call 1-833-496-1390 for expert service.
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Hopkins Trailer Wiring - HM48240

  • Trailer Connectors
  • Trailer End Connector
  • 4 Flat
  • Plug and Lead
  • 11 - 20 Feet Long
  • Hopkins

Wishbone-style Y-harness features a 4-pole flat connector with a convenient, simple-to-use, easy-pull grip for effortless disconnect. Rust-resistant terminals are further protected by a molded dust cover, and all wires are color coded.


  • Provides simple, efficient method for rewiring your trailer with a 4-way flat trailer-end connector
  • Wishbone design - Y-harness contains 2 separate, brown tail light wires
    • Left-side tail light wire is bundled with the yellow left turn/brake wire
    • Right-side tail light wire is bundled with the green right turn/brake wire
  • Easy-pull, ergonomic grip on connector makes disconnecting a snap
  • Heavy-duty connector housings have built-in mounting holes
  • Durable, molded dust cover provides superior protection for terminals
    • Tin-plated terminals resist corrosion
  • White grounding wiring included
    • Serrated ground terminal ensures proper grounding
  • Nylon sleeve and heat-shrink tubing protect wires


  • Connector: 4-way flat
  • Harness length: 20'
  • Ground wire length: 36"
  • 3-Year warranty

48240 Hopkins Endurance 4-Wire Flat Y-Harness

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Customer Satisfaction Score:

Customer Reviews

Hopkins Endurance 4-Way Flat Trailer Wiring Harness - 20' Long - HM48240

Average Customer Rating:  4.8 out of 5 stars   (55 Customer Reviews)

Wishbone-style Y-harness features a 4-pole flat connector with a convenient, simple-to-use, easy-pull grip for effortless disconnect. Rust-resistant terminals are further protected by a molded dust cover, and all wires are color coded.


I used this harness to rewire a 10ft vintage RV. There was plenty of length to reach the rear lights. I used Scotch Locks to tap into the wiring for the side running lights. Very good product.


Very happy with every aspect of my order. Received product and quality appears to be outstanding. I’m especially impressed at the instructions made available to install the wiring harness, written with the product and link for video. All bases covered and follow up to make sure all goes well. Am confident of their assistance should I need it.

Excellent quality product, works like a champ , no signs of corrosion in spite of outdoor storage
Barry - 04/14/2021


This is the best plug system I have seen. Quality.


Before I start I want you all to know I am not good at anything with wires or water, period.
I had an old 4x8 trailer that needed to be re-wired. I was not looking forward to screwing it up which was inevitable If I touched it. But, I need the trailer for the July 4th weekend so by chance I ran across your site. I found the video on how-to rewire a trailer. Though you made it look easy *I* would be attempting this! Okay, the project took a bit of time since I questioned everything twice (about an hour) but I have to say, IT WAS NO PROBLEM re-wiring the trailer. The 4-way trailer harness is much better than the harness I had on it and the whole project was actually fun to do (and I hate this type of stuff). I love the quality and really love the connector 'cap', even though the trailer is garage kept.
Thanks for the products and the video assistance, it was easy because of you!


This is an excellent alternative to purchasing the 4 way connector alone. All leads are built into the connector, which means you don't have deal with that part of the installation process. The ground wire has a good length to it, with the screw end circle easily fastened to the trailer. The length of the other wiring allows for you to completely rewire a small trailer like the one that I've replaced. I recommend this product if you're looking for a hassle free replacement or upgrade of your existing trailer wiring system.


Had to replace my electrical wiring for my boat trailer. Mice had chewed the previous wiring. etrailer wiring kit was delivered on time per all expectation, great price. Installed effortlessly, this time I closed off the entry points for rodents. Thank you etrailer


better than it needs to beWiring harness is nicely assembled, with an anti abrasion sleeve on the end, nie weather cap for the connector, grounding lug is already attached. It even includes attachment screw for grounding lug, and terminal grease to help fight corrosion. My dog ate the head off of my old harness and it was cheaper to replace the entire harness than to splice and curse and add assorted parts. This harness is COMPLETE, and will really do the trick. Quick delivery, reliable


I am really impressed with etrailer. i got my wiring harness in the mail to day and had the trailer wired up in about an hour. love the ease of wiring the trailer with the two sets of wires.


Used this wiring harness to replace the existing one on my utility trailer. So nice to have reliable lights now.


Very solid product! It gives me confidence it will last a long time. I would have preferred to be able choose a coiled harness of the same gauge wiring but wasn't able to find one. Instead, I took this one and adding some flexible tubing to allow it to stretch when turning, and it works well enough


the wire harness is exactly as described. the only thing i dont like about it is the thin insulator around the wires. wires on trailers are constantly rubbing on something, and this harness is lacking good insulation. it looks similar to cheap speaker wire. i bought a roll of split loom to put the wire in. plug appears to be nice and sturdy. iv only plugged it in once to make sure might lights work....but it looks like it should be fine. 4 out of 5 stars.


Quality product- exactly what I needed- Excellent customer service- A++++++


Product looks to be top quality and was delivered to me with out issue. I will be installing it on a utility trailer I have that the original wiring on is starting to malfunction due to wear. This product interested me because of the durable wrapping and split leads for each side. Thanks and I will be using for any of my future trailer accessory needs.


Works well.


Great value and the communication and shipping time couldn't have been better.Can't wait to wire up the lights for the hitch mounted rack for my Honda F6B.


Excellent product but found it to be too short for utility trailer I’m rewiring and had to order a different harness that is longer


this company had an excellent price and service was top notch.
items were not only shipped the same day, they were shipped immediatelly following the order, and arrived a few days later.
thank you for the great service i will probably use the website again for other trailer parts.


Got the tires, wheels, lights, and wiring kit to rebuild an old utility trailer. The website has a wealth of info to help find exactly what was needed. Michelle S. was very helpful (and friendly!) in resolving a delivery question.


This harness was a great solution for my trailer project. Has held up very well.


Just what i needed. my dog also likes the taste of trailer plugs.
Its exactly as shown in photo.
Quick delivery.....Thanks again


Great product for rewiring an old trailer. Got it installed in about an hour and I have lights again. Thanks.


this is an excellent product. it has solved all my problems with spliced wires on my trailer.also very easy to install in the existing hangers


Fantastic product. Easy to install. The 4 pronged connector is well made and is not flimsy like other connectors.


Assembled today, perfect. Everything worked as planned. I am SO happy with etrailer. Everything I have purchased from them has been above expectations and customer service has been awesome. Thank You!


I received my order yesterday and I am very pleased with the y harness

Show More Reviews

See what our Experts say about this Hopkins Trailer Wiring

  • Replacement Wiring Recommendation For Small Trailer With No Brakes
    If you are wanting to re-wire your trailer, we have just what you need. For a small trailer with no brakes I recommend the Hopkins Endurance 4-Way Flat Trailer Wiring Harness, part # HM48240. This is a wishbone harness that has 2 separate, brown tail light wires which is nice so you do not have to tee intot the wiring for your running lights. The left-side tail light wire is bundled with the yellow left turn/brake wire and the right-side tail light wire is bundled with the green right...
    view full answer...
  • What Guage Wire Does Hopkins 4-Way Trailer Wiring Harness Use
    The Hopkins 4-Way flat Trailer Wiring Harness uses 18 awg stranded wire for the right turn, left turn and tail light functions. The ground wire is 16 awg. Hopkins does a really nice job with this harness, they have each of the wires marked about every six to eight inches with the function of each of the wires. Each of the wires also has the color coded stripe that correlates to the function. The green striped wire is for your right turn, the brown striped wire is taillights and the yellow...
    view full answer...
  • Trailer Lights Do Not Work when Connected to Truck But Work with AC to DC Converter
    First, when lights work intermittently that is an indication of a ground problem. It could also be a loose connection somewhere or a dirty/corroded trailer connector. Ground problems normally show up when there is more draw on a system such as when you have the running lights on and then use another function like a turn signal or brake light. Make sure that the vehicle side and trailer side connectors are clean and free of corrosion inside and out. The main connector grounds should be...
    view full answer...
  • How to Wire In Side Marker Lights to Hopkins Endurance 4-Way Flat Trailer Wiring Harness # HM48240
    The Hopkins Endurance 4-Way Flat Trailer Wiring Harness, # HM48240, is a wishbone style trailer wiring harness. This means that the running light signal is split at the plug and there are two separate wires, one ran with the right turn/brake green wire and the other ran with the left turn/brake yellow wire. It does not come with additional wiring for side marker lights. If you were to wire in side marker lights, you would tap into the wire with the brown stripe for either side.
    view full answer...
  • What Gauge Wire is Used in the Hopkins Endurance 4-Way Flat Trailer Wiring Harness, # HM48240
    I went out to the warehouse and pulled a Hopkins Endurance 4-Way Flat Trailer Wiring Harness, # HM48240. The copper strands inside the wires are 18 gauge. With the jacket on it is between 10 and 12.
    view full answer...
  • Troubleshooting Trailer Wiring Where All Lights Blink with Left Turn Signal
    With your 2015 Ford F-150 it sounds like there is a bad ground on your trailer or a bad connection. First I recommend using some sand paper on your wiring connection to ensure there is good contract between the pins free of corrosion and debris. The Hopkins Endurance 4-Way Flat Trailer Wiring Harness - 20' Long # HM48240 may be connected correctly and work well with a different vehicle that has a different power output, but often when there is an issue like you are describing it's a...
    view full answer...
  • Hopkins 4-Way Trailer Side Connector Fits Tow Ready Vehicle Side 4-Way Connector on 2008 Ford Escape
    I went out to the warehouse and pulled trailer wiring harness # 118251 and Hopkins harness # HM48240 to see if they are compatible. They do fit together just fine and will work great together. I also made a video which will appear on this page showing the 2 being used together.
    view full answer...
  • 2002 Toyota Tundra Does Not Have Correct Plug to Match Recommended Custom Wiring, What Can I Use?
    It looks like the 2002 Toyota Tundra should have an 8-pin square connector on the rear of the vehicle for the trailer wiring, and from the photo you're showing that is definitely not an 8-pin square connector; it's a 6 pin square. One of two things could have happened here. I would first make sure that you've pulled the correct plug, since there are two very similar plugs placed right next to eachother on the 2002 Toyota Tundra. I've taken a screenshot of our installation video as a reference...
    view full answer...
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  • Left Brake Light on Trailer Does Not Work but All Other Lights are Working
    The brake lights on a trailer are on separate circuits. There is one circuit for left turn and brake lights and another circuit for right turn and brake lights. If the turn signal is working on the left side but not the brake light, then it is most likely a bad ground connection. Ground problems normally show up when there is more load on a circuit like the constant 12 volt draw of the brake light. Check the ground for the left side taillight. Many trailer lights ground through the mounting...
    view full answer...
  • Odd Voltage Readings and Malfunctioning Trailer Lights w/Curt Harness Installed on 2004 Lexus RX330
    It sounds like the converter box may have shorted out, which can cause high and low voltage readings. To verify this, you will want to test the power going into and out of the converter box. If all power readings are fine going into the box but not coming out of the converter, then we'll know it is a problem with the box and not an issue with your Lexus. I've provided a link to our article on troubleshooting 4 & 5-way wiring installations which may be helpful. It is most likely a short...
    view full answer...
  • Lights Only Work On One Side of Trailer When Connected to 2005 Ford F-150
    It sounds like there could be a wiring issue on the truck more so than your Hopkins Endurance # HM48240 4 way connector. Since you've already checked the harness, you likely would have noticed any corrosion or damage to the pins; so I would start by checking to make sure that the wiring harness is connected to everything firmly and that all of the vehicle grounds check out- make sure that the ground is connected to a paint and debris free surface.If the ground checks out, you'll need to...
    view full answer...
  • 2012 Demco Kar-Kaddy 3 KK370SB Wiring Replacement
    For your 2012 Demco Kar-Kaddy 3 KK370SB, we don't have the specific kit but the wiring used is just a simple 4 way wiring harness in the wishbone style. I recommend using # HM48240 as a replacement for your current harness. I've attached an article to help as well as a video.
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  • Troubleshooting Trailer Right Turn/Brake Lamp Circuit
    The first thing you'll want to do is determine if the problem is on the vehicle or in the trailer wiring. With the right turn signal activated, check the pin in the 7-way in the 3:00 position with a circuit tester like # PTW2993. If the tester blinks along with the turn signal, the problem lies in the trailer wiring. If you do not get a signal, check the 7-way for damage and corrosion and repair or replace as needed. If the connector checks out okay, if the vehicle has a factory tow package,...
    view full answer...
  • What Gauge Wire Is Used On the Hopkins Endurance 4-Way Flat Trailer Wiring Harness?
    The Hopkins Endurance 4-Way Flat Trailer Wiring Harness - 20' Long # HM48240 uses 18 gauge wire for the 3 lighting functions and 16 gauge for the ground wire. This is standard size wire for a 4-way flat harness, but the ergonomic grip on the connector for the easy pull disconnection is what sets this harness apart from others. I recommend using the Deka Heat Shrink Butt Connector - 22-18 Gauge - Nylon Insulation - Red - Qty 10 # DW05743-10 for your light connections.
    view full answer...
  • How to Determine the Functions of 4-Way Flat Trailer Connector when All Wires are the Same Color
    Yes, on a 4-Way flat trailer connector there is one covered pin and 3 exposed pins. The one covered pin is the ground. Next to it is the running light pin. Then the left turn signal/brake light pin. And the last pin is right turn signal and brake lights. If any of the lights light up when you applied power to the ground then there is a short somewhere that will need to be fixed. That will be easy though since you can just attach a new wire to the ground wire at the back of the connector...
    view full answer...
  • How to Install Ground Wire To Trailer Connector on Utility Trailer
    Grounding through the ball doesn't work well, as you've found. If the current harness doesn't have a ground circuit, the wiring must be fairly old as it's pretty typical for a trailer connector to have a ground circuit. The fact that you're blowing fuses leads me to believe you might also have a short circuit in one or both your turn signal/brake lamp circuits. You'll want to replace the existing wiring harness on the trailer. This is pretty simple to do, and will only take an hour or...
    view full answer...
  • Installing Trailer Lights on a Non-Metal Frame
    Good news, I can help. You can simply connect an extension wire like part # DW02359-1 from the ground wire on the # STL8RB light to the trailer's main ground connection or to the metal trailer tongue. We do have a trailer wiring installation kit # HM51020 that will make installing the Hopkins # HM48240 harness to the trailer a little easier. I have linked all the above mentioned parts as well as a Help Article for your viewing and purchasing convenience.
    view full answer...
  • Parts Needed to Replace Wiring On Car Tow Dolly
    The replacement needed will depend on which trailer connector your car dolly uses, a 4 pole or a 7-way. For a 4-pole, a standard trailer wiring harness like # HM48240 would work well for you. If the tow dolly has a 7-way connector on it with electric brakes, I'd go with something like # 277-000141 to provide the trailer connector and junction box. The junction box allows you a safe spot to make your connections that will keep moisture away from the wiring connections. You'd use a length...
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  • Replacement Lights and Trailer Harness for SnowBear Trailer
    To replace the wiring harness on your Snowbear trailer you can use the Hopkins Endurance 4-Way Flat Trailer Wiring Harness - 20' Long # HM48240, which is a nice option since it gives you running light circuits running down both sides; this will make wiring everything in easier. If you also want to replace the lights with LED lights, you will need to swap all lights on the trailer to avoid issues with combining LED and incandescent lights. To replace the tail lights I recommend using the...
    view full answer...
  • Replacement Trailer Side 4-Pole Connector for Boat Trailer
    We do offer replacement trailer-side 4-pole wiring kits that you can use to replace the damaged one on your boat trailer. For a trailer-side 4-pole we offer various lengths, such as the 4-foot Wesbar # W787264, 8-foot harness # W787268 and 14-foot # W787274. The Hopkins part # HM48240 that you referenced is a similar 20-foot harness. This features a wishbone construction, which means dual running light wires so that there is one for each side of the trailer. We also have a 35-foot long...
    view full answer...

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