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20 Ft 4-Way Trailer Wiring Harness - Wishbone Style - 30" Ground

20 Ft 4-Way Trailer Wiring Harness - Wishbone Style - 30" Ground

Item # A20WB
Our Price: $18.10
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Trailer Wiring
Shipping Weight: 0.7 lbs
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4-Way trailer harness connects to your tow vehicle to control trailer light functions. Wishbone-style harness comes with 2 tail light wires split for simple wiring. Great Prices for the best trailer wiring from Optronics. 20 Ft 4-Way Trailer Wiring Harness - Wishbone Style - 30" Ground part number A20WB can be ordered online at or call 1-800-940-8924 for expert service.
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Optronics Trailer Wiring - A20WB

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

4-Way trailer harness connects to your tow vehicle to control trailer light functions. Wishbone-style harness comes with 2 tail light wires split for simple wiring.


  • 4-Way trailer harness connects to your tow vehicle to control trailer light functions
  • Wishbone-style harness comes with 2 tail light wires split for simple wiring
    • Allows you to run wires separately down each side of the trailer to tail lights without needing a jumper wire
  • Color coded wires help with installation
    • White - ground
    • Brown - tail lights
    • Yellow - driver side stop/turn
    • Green - passenger side stop/turn


  • Wire harness length: 20'
  • Ground wire length: 30"
  • Wire gauge: 20 AWG

A20WB Optronics 20 ft. Wishbone 4-Way Trailer Wiring Harness with 30" Ground Wire

California residents: click here

Video of 20 Ft 4-Way Trailer Wiring Harness - Wishbone Style - 30" Ground

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

Video Transcript for Review of Optronics Trailer Wiring - Trailer Connectors - A20WB

Hello everybody. This is Jeff at Today we're gonna take a look at this Optronics 20 foot long Wishbone 4-Way Trailer Wiring Harness. Now this 4-way trailer wiring harness will install on your trailer and connects to your tow vehicle to control your trailer light functions. This one we call a wishbone-style harness 'cause it's designed to have two brown taillight wires, one for each side of the trailer, that'll split for simple wiring of your trailer. This will allow you to run wires separately down each side of the trailer to your taillights without needing a jumper wire.

If you notice the ground wire on this with the eyelid on it, is the white wire that has 30 inch length to it. We mentioned the total wire harness length is 20 feet, and the wires are color coded, so that'll help with installation. We mentioned the white is your ground. The brown, there's two of 'em, one for each side, those are your tail lights, and then you'll notice the brown right here. If we do the brown and the yellow side, that's for your driver's-side stop and turn, and this one here is the brown and the green wire, which is your passenger-side stop and turn.

So you just run those down each side, driver's side and passenger side, and you don't have to run a jumper wire in between. But that should do it for the review on the Optronics 20 foot long Wishbone 4-Way Trailer Wiring Harness.

Customer Satisfaction Score:

Customer Reviews

20 Ft 4-Way Trailer Wiring Harness - Wishbone Style - 30" Ground - A20WB

Average Customer Rating:  4.8 out of 5 stars   (299 Customer Reviews)

4-Way trailer harness connects to your tow vehicle to control trailer light functions. Wishbone-style harness comes with 2 tail light wires split for simple wiring.


Wiring worked perfect for my project. I replaced the wiring on my 14 foot utility trailer. If I was to do it again I would buy the next length up. I would have liked to have a little extra wiring if I was to ever need it.


Worked perfectly with the trailer light s.


Quality harness. Not the cheap HF low quality wiring..


Great service and one of the only spots I can find the wishbone style plug!


It's a simple item but try to find it somewhere else as a stand alone product.
I've used etrailer before with great results and this was no exception. Let's be honest, if you've been to the site once, you're coming back!
I have a 5 x 12 utility trailer that has good lights but the wiring was a disaster. The harness connector had been patched and there were at least 5 splices throughout the lines. It was nice to lay out the new harness, make the light connections, tack everything up and out of harms way (there's an idea) and my lights work like new. I like the ground fastens under the jack bolt. Saves drilling a screw in (see the baby hole?) Good to feel safe on the road again. As easy and inexpensive as it was, I don't know why I waited so long.


Worked out very well and no issues a year later.


After trying to spice wires with other kits I found ETRAILER made a order got in just a couple days and had it wired hassle free this is a great product and I even order another one for my boat trailer and a easy plug kit for my jeep!! Will continue to use ETRAILER in the future!!


great products and pricing with a fast delivery time. Thanks


Product exactly as advertised, and excellent variety of inventory.


Some men, when they arrive at sixty five or above, run out and buy a fancy red sports car. I bought an old trailer that looked good and sturdy. It was very inexpensive. It needed some welding and rewiring. Luckily I have a neighbor who is an excellent welder, and the wiring was easy to find on the web and easy to install. I have gotten great pleasure using my trailer. I even thought about painting it red, but then that would look ridiculous.



Very good. Product has held up nicely


Just wanted to let you know that the Optronics Miro-Flex Trailer Lights are working great!! Much brighter and more visible that the basic lights I replaced! Hope your business is doing well through this Covid crisis!! Thanks for the communication.

Michael I.




Just rewired a cargo trailer I bought that the lights were always going out. Found 20 butt connectors the guy used no wonder they worked off & on. Now with two new tail lights & new wiring with a straight connection everything works like it should. Everything I have bought from etrailer has been good quality & fast shipping.



Cheap--wired it in to my Chevy and tried to separate the male connector from the female and the rubber sleeve separated from the terminals on the make connector. Threw the GARBAGE into the garbage and re-installed my old one. Do not buy this cheap junk. Wish I would have taken a photo.


The product was as advertised. And shipping was completed within just two days. My only potential suggestion would be to provide single page schematic to connect the wiring to the tail light unit.


I have been very pleased with the quality of the product and that it is very durable and works great . The wire seems to be holding up well



Great very durable product


Fantastic !!!! Great product, exactly as detailed, exactly as pictured, easy ordering, and on time shipment / arrival. I have never wired a trailer before, but after watching the online video program and following the steps I was able to complete the project in a hour for a 14' boat trailer. Prior to ordering, I did a lot of price comparisons in my area and I could not beat etrailer pricing. Great product.

Martin F.


Thanks for the follow up - One year later the products are working spectacular and I keep plugging away at your company - telling all of my friends about it.


Harness was purchased to rewire my Shoreland'r boat trailer. It came very well
packaged. The internal wire was strong and did not fray when stripping off the sheath. The main thing I liked was that the right and left (gr/br & yel/br) wires were separated all the way to the connector. The shipping fees were very reasonable. I would recommend this product all day. THANKS Now if I could just figure out why I keep blowing my running lite fuse in my truck???

Etrailer Expert

Heather A.


First you want to make sure your ground wires on your vehicle wiring and your trailer wiring are attached to bare corrosion free metal. If your grounds are properly attached, It sounds like you have a short circuit somewhere. You need to determine where the short is. To determine where the short is you need to test the vehicle side wiring and the trailer side wiring with a 12v probe-style circuit tester. I have attached a link below to help you.


Wishbone style is the way to go. Received harness today and installed this afternoon. I have ordered various items over time from etrailer and always satisfied.


Rewired the lights on my old trash trailer. Only took an hour. The cable was perfect. I was impressed with the four way connector.


What do y'all want a follow up to? If i had a nickel for every item I've ordered off of ETrailer, I wouldn't have to work for a few months... I keep coming back because the prices are fair, shipping is free and fast, and ETrailer has everything I need.

I do wish you sold trailer kits though. Being a welder, I have built a few trailers in my free time and sold them for a small side business. Why isn't there an axle, fender, brakes, springs (shackles and all hardware) tires and wheels kit? It would be nice to not have to go and click and add to cart all the multitude of items I need to build a trailer individually. Just saying...


Good quality, easy to install, and no issues after one year.


Exactly what I needed to begin rewiring a trailer. My sons cattle ate the trailer plug and pulled out the wiring in the tongue.

John M.


No problems! I installed in on my brother-in-laws work van and he hasnt complained.


Works great,



Still working good




I bought a homemade raft trailer that had some electrical issues. I decided to start from scratch and rewire the lights instead of troubleshooting and to know that it was done correctly. It took me about an hour to remove existing wire and rewire two side marker lights and rear turn/brake lights with this wiring kit. Everything worked great when finished and the price made my time totally worth it. I'd recommend this to anyone.

Show More Reviews

See what our Experts say about this Optronics Trailer Wiring

  • Wire Gauge and Ground Locations for LED Running Lights on a Trailer
    Since LED lights do not require a lot of amperage you can go with relatively small wire. Using 16 or 18 gauge wire will be fine. Harness # A20WB uses 20 gauge wire which is on the small side but certainly not a problem at all for LED lights even incandescent lights on a trailer. We have various types of 16 and 18 gauge wires, see links, depending on the configuration needed. Also many of the options are sold by the foot so you would change the quantity amount to reflect how many feet you...
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  • Wire Gauge for the Wishbone 4-Way Trailer Wiring Harness, # A20WB
    I spoke with my contact at Optronics about the Wishbone 4-Way Trailer Wiring Harness, # A20WB. They had documentation stating the green wire is 19 gauge and the yellow wire is 20 gauge. She could not state for sure what gauge the white and brown wires are but either 19 or 20.
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  • Replacement Wishbone 4-Way Recommendation for a Trailer
    You are correct. Based on the wire colors that you listed you would want a wishbone 4-way like the part # A20WB. The colors of this 4-way would match up exactly to what you have listed with the only addition being the white wire of the new 4-way running to a clean metal surface on your trailer. The brown wires of the 4-way will be run to the yellow/brown and the green/brown wires. It doesn't matter which one as it's the same circuit (running lights). I attached an install video for...
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  • Recommended 4 Flat Wishbone Harness for Trailer
    The shortest 4-Way wishbone harness we currently have available is the 20 foot Optronics Wishbone 4-Way Trailer Wiring Harness # A20WB. This is a split wishbone 4-way trailer wiring harness that features the two brown tail light wires that you referenced. All the wires are 20-AWG gauge. Since the harness is a bit longer than you are needing, I recommend simply taping up any excess wire once the connector is installed. I have attached a couple short video demonstrations on this harness...
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  • Can 4-Way with 4 Wires be Used with 4-Way with 5 Wires
    Yes, the 4-ways with 4 wires and the ones with 5 wire perform the exact same functions so they both can easily be used together. What you have a picture of is a wishbone 4-way that has the two running light circuits on it. One for either side of the trailer. That's why it has 5 wires. The 4-wire 4-ways use a single wire for this circuit but you then have to split it off to either side of the trailer. The two wires in your picture that have brown on them are that circuit. # A20WB is an...
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  • What Color Are the Brake Lights On A 4-Way Flat Plug Of Wishbone Wiring Harness?
    The brake signal is run along with the blinker on separate wires. The passenger side is normally green and carries the right turn and brake light. The driver's side is normally yellow and carries the left turn signal and brake. The remaining functions are running/tail lights on the brown wire and the ground which is the white wire. I've attached an article to assist. A wishbone harness like # A20WB will give you two brown wires so you don't need to run a jump wire from one side of...
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  • Why Would Trailer Wiring have Two White and Brown Wires
    It's not uncommon for trailer wiring to have more than one wire for the same circuit for the ground and running light circuit. For the running light circuit (brown wire) this is to allow you an easier way to run the circuit to either side of the trailer. For the ground circuit (white wire) it's to allow for making more ground circuit connections easier since all of the circuits have to be grounded. So if your trailer has two ground wires you could run them both together and then to the...
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  • Wire Color for Each Function on 4-Way Trailer Wiring
    You likely saw it on our wiring help article which I linked. The traditional wire coloring of a standard 4-way like # A20WB is both browns to your running lights, one per side of the trailer, green to your right turn and brake light, yellow to the left turn and brake light, and the white is the ground wire.
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  • Should Boat Trailer Lights Short Out When Backed Into Water
    Water and electricity don't mix well. The best recommendation I can make for you would be to unplug your trailer wiring before you back your boat trailer down the ramp and then don't plug the lights back in until the trailer has dried out thoroughly. While the trailer lights themselves can be listed as waterproof or submergible the wiring of the trailer isn't always so that is why unplugging the trailer lights is recommended. If the assemblies were ever replaced water can easily get in...
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  • What is the Wire Material Made of on the
    I went out to our warehouse and pulled the wiring harness. The wire in the Optronics Wishbone 4-way Trailer Harness, # A20WB, is copper.
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  • Recommended 6 Foot Long Wishbone Wiring Harness for Boat Trailer
    The shortest wishbone 4-Way trailer wiring harness we have available is the Optronics Wishbone Harness # A20WB. This wishbone harness, which has the 4-flat connector with 5 wires, features 20 feet of wiring length. Since this is a bit longer than what you are needing, you can simply tie off any excess once you have everything installed. All the wires are 20-AWG gauge. I have also attached a couple video demonstrations on this product that you can check out.
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  • Trailer Lights Function Differently on Two Different Vehicles
    If you have different lighting issues with the trailer depending on which vehicle you are using then that leads me to believe there is an issue on the vehicle. I recommend you check the trailer lighting circuit fuses on each tow vehicle to make sure all is in order. Also, I recommend you run a ground jumper wire for each light up to the main trailer connector ground as well temporarily to see if that fixes your issue. If you want to check the trailer on its own then you can do so with the...
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  • How to Wire Up New 4-Way to Trailer When Wire Color Functions are Unknown
    It's interesting that your trailer connector has two green wires but aside from that standard wire colors. Typically white is ground, brown is running lights (where you would normally see 2 wires of same color), yellow is left turn/stop, and green is right turn/stop. You might try putting 12 volts via a car battery on both of the green wires to see what they illuminate. You may even try this for all of the color wires minus the white to make sure you have the functions determined. For...
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  • How Does Wishbone 4-Way Wire to Trailer's 4-Way Wiring that has 7 Wires
    The two white wires are the ground circuit which would run to the white wire of the # A20WB, the black wire has to be the right turn/stop signal although that color is typically solid green. The brown is a running light circuit that runs to clearance lights on the trailer, the yellow brown runs to the taillight assembly for the running light circuit, and green brown is the left turn/stop circuit. All of these run to either of the brown wires of the 4-way, and then the yellow is the left...
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  • Will 20 ft. Wishbone 4-Way Trailer Wiring Harness # A20WB work with LED Trailer Taillights
    Yes, the 20 ft. 4-Way plus Wiring part # A20WB that you referenced will work great with LED trailer lights. There's no reason that it wouldn't work. This is a wishbone wiring kit for the running light circuit which means that the running light circuit has a wire for each side of the trailer. That's why there are two brown wires. I attached an install video for this kit for you to check out as well.
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  • Troubleshooting Trailer Lights That Stopped Working After Bulb Replacement
    There is no difference between the red and amber colored trailer lights. They are the same lights with a different color lens on them. If all of the lights on your trailer went out I would suspect you blew a fuse somehow in the process of replacing the light. I would check the fuse box of the vehicle you connected this trailer to looking for the trailer wiring fuses and replace as necessary. I attached an FAQ on trailer wiring as well as troubleshooting 4-way installs that should be helpful...
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  • No Brake Lights or Turn Signals on Trailer With a 4-Way Connector With 5 Wires
    You will first want to make sure the 5 wires on the trailer plug is wired properly to the trailer. The white wire is for ground, the green wire for right turn and brake, yellow wire for left turn and brake, green with brown wire is for right side running lights, yellow with brown wire is for left side running lights. If the wiring is all correct then you will need to check the trailer connector on the truck and trailer for a ground connection issue, or a short on the tail light circuit...
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  • Does Optronics A20WB Trailer Wiring Harness Use All-Copper Wire
    The Optronics 20 foot 4-way trailer wiring harness, part # A20WB is constructed of 18 gauge stranded all-copper wire. I've confirmed this with my Optronics representative.
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  • What Gauge Wire is Used in the Wishbone 4-Way Trailer Wiring Harness, # A20WB
    I spoke with my contact at Optronics about the Wishbone 4-Way Trailer Wiring Harness, # A20WB. They had documentation stating the green wire is 19 gauge and the yellow wire is 20 gauge. She could not state for sure what gauge the white and brown wires are but either 19 or 20.
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  • Troubleshooting Trailer Stop/Turn Circuit Not Active for 2011 Jeep Grand Cherokee
    It should be a fuse that is called trailer wiring right stop/turn circuit in the fuse box. It could also be cut wire up stream of the connector as well. I pulled up the owners manual for your 2011 Jeep Grand Cherokee and the only trailer towing fuse listed is in the J14 lamps and it looks like it covers all the circuits. That makes me think that your problem is actually on the wiring of the connector and not on the vehicle.
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  • Replacement Trailer Wiring Harness for 2017 Honda Pilot with Fried Converter Box
    Just the converter box of the trailer wiring for your 2017 Honda Pilot isn't available so you'll need to swap to a new kit altogether. For that the most reliable option we have is going to be the Tekonsha kit part # 118760 as it has the highest amp rating and also the reputation as being most reliable.
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  • Wiring Harness for a 2011 Kia Sedona
    The wiring kit you will need for your 2011 Kia Sedona is the T-One Wiring Harness # 118410. This kit will give you a 4-way connector to to power up the lights on your utility trailer. For your trailer you can use the 20 ft. Wishbone 4-Way Trailer Wiring Harness with 30" Ground Wire # A20WB. I've added links to install videos of each of these products as well as a help article on trailer wiring which you may find useful.
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  • 4-way Wiring Recommendation for a Wishbone Wired Boat Trailer
    What you have is a wishbone 4-way that seems to have a few circuits run to the ground circuit (the jacketed circuit that has the 2 white wires plus the green wire with the white tracer). What you could use would be a 20 ft. Wishbone 4-Way Trailer Wiring Harness # A20WB. This has the wishboned running light circuit. Aside from that you would need to run all the wires to the ground circuit of the # A20WB. Basically you will need to run the wires all together from each circuit of your boat...
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  • Trailer Lights Stop Working When Headlights are Turned On with a 2007 Chevrolet Avalanche
    The most likely cause of your problem is a bad ground connection. It has enough of a connection that it works in the day time because you have less current draw on those circuits with the head lights off. As soon as the headlights are on, you are pulling more current than the weak ground can support. Check the ground connections on the trailer wiring. Make sure you have good metal to metal contact. Paint and corrosion can act as insulators so make sure the grounds are touching clean metal....
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Info for this part was:

Employee Mike L
Expert Research:
Mike L
Employee Robert G
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Robert G
Employee Patrick B
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Patrick B
Employee Michael H
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Michael H
Employee Jeff D
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Jeff D
Employee Jameson C
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Jameson C
Employee John H
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John H
Employee Adam R
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Adam R
Employee Cole B
Installed by:
Cole B
Employee Wilson B
Updated by:
Wilson B
Employee Brian T
Updated by:
Brian T

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