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25 Ft 4-Way Trailer Wiring Harness - Wishbone Style - 25' Ground

25 Ft 4-Way Trailer Wiring Harness - Wishbone Style - 25' Ground

Item # A25W2GWB
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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. Lowest Prices for the best wiring from Optronics. 25 Ft 4-Way Trailer Wiring Harness - Wishbone Style - 25' Ground part number A25W2GWB can be ordered online at etrailer.com or call 800-298-1624 for expert service.
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  • Reviews (91)
  • Q & A (15)
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Optronics Wiring - A25W2GWB

  • Trailer Connectors
  • Trailer End Connector
  • 4 Flat
  • Plug and Lead
  • 21 - 30 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: 25'
  • Ground wire length: 25'
  • 3-Year Warranty

A25W2GWB Optronics 4-Way Wishbone Trailer Wiring Harness with (2) 25' Ground Wires - 25' Long

California residents: click here

Video of 25 Ft 4-Way Trailer Wiring Harness - Wishbone Style - 25' Ground

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

Video Transcript for Optronics Wiring - Trailer Connectors - A25W2GWB Review

Speaker 1: Today we're taking a look at a Four Way Wishbone Trailer Wiring Harness. This wishbone style harness allows you to easily rewire your trailer with a four pole flat trailer connector being up towards the tongue so you can easily connect to your vehicle. This is a wishbone style harness. It has an extra taillight wire that makes it easier to wire your trailer. We have the four pole flat trailer end connector. Easily plugs into the tow vehicle.This is a 25 foot long wire harness.

So all the wires are 25 foot long, even the ground wire. So the white wire on the unit is the ground wire, runs the full length of the harness. We have one ground wire on each side that extends, again, the full length: front to back.Now when it comes to the wire coloring, you'll see coming out of the plug we have two white wires. Those are the ground wires. We have two brown wires.

Those are our taillights. We have the yellow wire, which is for the driver's side stop and turn signal. And then we have the green wire, which is for the passenger side stop and turn signal. That's gonna do it for today's look at the Four Way Wishbone Trailer Wiring Harness.

Customer Reviews

25 Ft 4-Way Trailer Wiring Harness - Wishbone Style - 25' Ground - A25W2GWB

Average Customer Rating:  4.7 out of 5 stars   (91 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.

- A25W2GWB

Glad somebody makes this type of harness with full-length ground wires on each side of the trailer. Wire guage is about 18 according to my Klein strippers. It appears to be copper. The plug lists Taiwan as country of origin. I'm happy with the product for the price. With a careful, proper installation, this should provide trouble-free service for many years. I gave 4 stars. With a more substantial plug-to-wire attachment, I would give 5.

- A25W2GWB

Nothing like leaving town at dusk only to find out at the first rest stop that your trailer lights are intermittently working. Ive used etrailer wiring harnesses in the past which surpassed the original harness. Buy with confidence.

- A25W2GWB

A year after purchase and installation, the wiring harness and submersible LED taillights are functioning as expected. I am very pleased with the product and service etrailer provided.

- A25W2GWB

I purchased this wiring harness to replace one for my cousin on her trailer. Everything was as it should have been..the install job was much easiernot having to battle the harness as well as the old trailer. One year later and everything is still A Ok.

After a year of use, wiring harness has held up well. No issues to speak of. Money well spent.
Russ S - 06/08/2021

- A25W2GWB

The wiring harness design is fantastic, and I was able to re-wire easily. The only negative is that the wire is this - I believe 18 gauge. If I had a choice, I would have preferred 16 gauge wire - 14 gauge would have been kick-butt, but perhaps overkill. Anyway, I've got new LED lights working great off of new wiring! Yeah!!

- A25W2GWB

So easy to find what you need, and pricing is always reasonable. First stop for all my towing and trailer needs.

- A25W2GWB

Overall quality is very good. Product was just as described. Prompt shipping. The only thing that would have made it better is having tinned copper instead of bare copper wire. But that should not be an issue if waterproof heat shrink tubing (adhesive inside) is used for the connections.

- A25W2GWB

Used this to install lights on a curt folding cargo carrier, was good to have 2 ground wires(white) and 2 parking light wires(brown), to avoid extra connectors that would cause corrosion problems

- A25W2GWB
by: 06/02/2021

This makes wiring tail lights so much easier. I always had to run the white ground wire to each light separately on my trailers. I had a few tilt boat trailers that wouldn't always ground the lights through the rusty tilt bolts. This harness makes the process easier, going to order another one soon.

- A25W2GWB

My trailer light problems finally solved the separate grounds are a great idea.

- A25W2GWB

Very nice Trailer light wire harness! It has 2 separate full length grounds to run all the way to the left and right tail lights. That assures you a perfect ground all the time as you are no longer relying on grounding through a screw into the frame and through the frame to another screw at the tail light. You now have a direct ground wire from your vehicle to the trailer lights! Speedy shipping! You will not find this type of harness anywhere else.

- A25W2GWB

I paid $[XX] (plus shipping) more than what I could have purchased this wiring harness local. The gauge (16) vs (14) on this wire is smaller wire (hope that is not an issue in the future). What caught my attention was the dual ground (that's a plus) ;however, there are no circle connectors or self-tapping screws to secure the ground(s).

- A25W2GWB

All good, I received the parts that I ordered they were of fine quality. No complaints.

- A25W2GWB

Wiring came pretty quickly, but the part Im really happy with is the part came as advertised! Fit my trailer perfect making installation so much easier!

- A25W2GWB

Everything worked perfect. It was an easy installation and lights are very bright.

- A25W2GWB

Working great as they should.

- A25W2GWB

Product is exactly as described, appears to have solid connectors, proper wire gauge and sturdy insulation. This will be exactly what I needed for my fishhouse project. I chose this product as it has the wishbone design with ground wires that i will run directly to the rear lights. Best part is that i longer have to rely on the chassis ground for my lights to work properly!! This was my first order with etrailer and I would recommend them for your projects. Ordering was easy, i was sent email with tracking numbers when the order shipped and was able to track the delivery of my package all the way to my door! Quality parts, excellent experience and i am very happy with this purchase! Nicely Done, etrailer Staff!

- A25W2GWB

This wiring harness looks and works per fect!

- A25W2GWB

Ordering was easy shipped and received as expected on time!! Very easy hook and instructions! would highly recommend this company and product!!

- A25W2GWB

It is a time*saver to have included in the same wiring an extra brown wire to do both tail lights independently; when wiring the trailer . I Love this thing .! I also Christina and e-Trailer, I get most of my staff from them when I need to build a trailer.

- A25W2GWB

This is the same wire harness that the OEM uses, it's a perfect replacement! Couldn't find the harness anywhere else, thanks E-Trailer.

Thanks to etrailer the lights on my boat trailer are worked perfectly all season, thanks again!!
James - 10/21/2019

- A25W2GWB

Outstanding first and second effort to Tiffany from etrailer thank you so much for resending my order at your expense to make sure your customer was satisfied thank you I truly hope the one that was juggled by UPS got back to you so you didn't actually have to cost the company just for my purchase but again in shock in all that I didn't take the hit I hope the company didn't either cheers one happy customer thank you again Tiffany

- A25W2GWB

Accurate fulfilment, timely delivery, good choice of delivery company, knowledgeable help from personnel on the phone.

- A25W2GWB

Excellent to be able to wire each side of the trailer from the very beginning at the tong . Time saver wiring .!

- A25W2GWB

Just as described

Show More Reviews

Ask the Experts about this Optronics Wiring

  • Recommended Trailer Wiring Harness for a Boat Trailer
    The Optronics 25 foot 4 Way Wire Harness # A25W2GWB will be a good option. This will generally have enough length to cover most trailers. I will also recommend adding in a few of the Spectro Self-Stripping Connector with Waterproof Sealant # SWC501746-1. These will make splicing into the # A25W2GWB significantly easier. Especially for your side marker lights.
    view full answer...
  • Should Ground Wire of Trailer Wiring Run to Frame of Trailer or Back to Light Assemblies
    Either option will work fine. If it was my decision to make I would ground the trailer wiring on the frame near the coupler since that's easiest and just as effective, but if you had an aluminum frame trailer or a dump trailer you'd have to run the ground wire back to the light assemblies so that they ground sufficiently. Most trailer lighting grounds through the mounting hardware which allows for an easier install so grounding the trailer connector to the frame at any location gives...
    view full answer...
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  • Troubleshooting Wishbone Wiring
    It sounds like the running lights are the issue as they are not functioning with your wishbone harness. I'm not sure what harness you have but a 4-way wishbone like # A25W2GWB will have two taillight wires, one for driver side stop/turn and the other for passenger side stop/turn. If your lights are not working, in order to determine the specific problem you will need to purchase a circuit tester if you do not have one - the very handy Cordless Circuit Tester # PTW2979 would be my strong...
    view full answer...
  • Availability of 16 Gauge Wire for Trailer Lights
    The Optronics 4-Way Wishbone Trailer Wiring Harness # A25W2GWB that you referenced has 18 gauge wire for the ground and 20 gauge wire for all of the lighting functions. I check with all of the other wishbone harnesses that we have and they all use similar gauge wiring none of which is 16 gauge. For 16 gauge wiring you can use the Deka Bonded 4 Wire # 16-4B-1 which is sold by the foot. I recommend using heat shrink butt connectors like part # DW05744-10 and the Quick-Fix Replacement 4-Way...
    view full answer...
  • Grounding a 4-Way Wishbone Trailer Connector
    The 4-way harness you looked at, part # A25W2GWB, has a ground wire. It's the white wire which is kind of hard to see in the pictures. This is a wishbone 4-way so there are two brown wires for running lights; one for each side of the trailer. Then the green wire is brake lights and the turn signals for the right side and the yellow wire is brake lights and turn signal for the left side.
    view full answer...
  • Tracker Boat Trailer Wires With 7 Wires Connecting Into A 4 Pin Plug
    It could be possible that your 2012 Boat trailer is wired with a wishbone style harness. Similar to Item # A25W2GWB. This type of harness just allows the installer to run each side separate rather than splicing and running extra wires across the bottom of the trailer. Your best bet may be to test each wire function before cutting. You cannot get trailer brakes from a 4 pin connector which is why I am leaning more toward it being a wishbone. Once you determine the proper functions all...
    view full answer...
  • What Type of Trailer Wiring Does Boat Trailer Typically Have
    Boat trailer 4-way trailer wiring is done in the same way as other 4-way trailer wiring. Sometimes boat trailer will use 5-ways instead if the trailer has surge brakes and the actuator has a reverse lockout which allows the trailer to back up without brake application. For that we have the part # HM37908 which comes with a 5 foot harness.
    view full answer...
  • How To Wire 4-Pole Harness with 5 Wires
    I can't comment on specific wire colors but it sounds like you're referring to a wishbone trailer wiring harness like part # A25W2GWB which has five wires and four pins on the connector. There will be two running light wires (one for each side), a left stop/turn wire, right stop/turn wire, and ground wire. The running light wires are usually brown/yellow and brown/green whereas the left stop/turn is yellow, the right stop/turn is green, and the ground wire is white. If your colors don't...
    view full answer...
  • Parts Needed to Add Wiring for Trailer Lights and Brakes
    I recommend using the etrailer Trailer Wiring 7-Way Upgrade Kit w/ Junction Box and RV Style Connector # e99011 to start off. This gives you a 7-Way connector and a clean and organized way to connect all of your wiring. Then for the wiring for your lights I recommend using the Wishbone Style Wiring Harness # A25W2GWB. This is 25' long which will give you enough for the length of your 16' trailer plus some extra wiring to make sure you have enough to connect all of your lights. You will...
    view full answer...
  • Is Wishbone 4-Way Required for Trailer With 4-Way but 5 Wires
    Yes you should! You are on the money with what you need, a wishbone-style 4-way wiring harness for your trailer. With this style, the white is ground, yellow is left turn/brake, green is right turn/brake, and the two brown wires are the running light wires. I'm not sure the length you need though, or if 35 feet might be too long, which is the length of the 4-Way Trailer Wiring Harness - Wishbone Style # A35W42B. We do have different lengths available, which I'll list for you just in...
    view full answer...
  • Replacing Trailer Wiring For Boat Trailer
    The running lights wire will run on both sides of the trailer and connect to any marker lights along the way to the Bargman Trailer Tail Light #30-92-001. I have linked a couple articles below for a 4-way and 7-way trailer wiring help guide. The 25 Ft 4-Way Trailer Wiring Harness # A25W2GWB is a great harness to use for your boat trailer if it uses a 4-way connector. This harness is divided at the plug to run the proper wires down both sides of the trailer for the tail lights and marker...
    view full answer...
  • Can 7-Way and 4-Way Both Install on Trailer for Separate Wiring Circuits
    When you say rear lights do you mean like utility lights so that you could see in the dark? If so you could just use the 12 volt accessory circuit of the 7-way to accomplish that. But aside from that you certainly could have two different connectors on your trailer for two different sets of lights. For a 7-way plug all you'd need is the part # 277-000143 and then for a 4-way part # A25W2GWB for 25 feet.
    view full answer...
  • Troubleshooting Trailer Lights on a Jayco Camper Flashing All Lights When Running Lights Are On
    It sounds like you have a short in your electrical harness. You will need a Test Light # PTW2993 to try and determine where the short is located in your harness. First begin by checking with the connection on your tow vehicle. You want to determine if all your lights blink when your running lights are on. If on a 4-way flat connector the female connector closest to the single male connector is the terminal that powers the running lights of the trailer. The center female connector...
    view full answer...
  • Trailer Wiring Harness Compatible with Peterson 435800 Trailer Stop/Turn/Taillight
    We don't offer a plug and play trailer harness that would plug directly into the Peterson # 435800 trailer taillight. The lamp includes a 3 pin pigtail that would plug into the rear of the lamp which would wire directly into the trailer wiring. If you need a 4 pole harness for your trailer, we offer them in varying lengths. • For a 20 foot harness, use part # A20WB • For a 25 foot harness, use # A25W2GWB • For a 30 foot harness, use # HM48265 • For a 35 foot harness, use #...
    view full answer...
  • Parts Needed To Install A Trailer Tail Light That Has 4 Wires
    I am unable find any lights like these that have the 4 wires for attaching to the light. You should be able to test each of the wires for their function using a 12 volt battery and connecting the wires directly to the terminals. My only concern is that your lights were set up to have separate brake light functions and that is why you have 4 wires. If that is the case and you want the lights to function properly you will have to run additional wiring and components as opposed to just using...
    view full answer...
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Info for this part was:

Employee Jameson C
Expert Research:
Jameson C
Employee Cole B
Installed by:
Cole B
Employee Daron K
Edited by:
Daron K
Employee Brian T
Written by:
Brian T

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