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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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25 Ft 4-Way Trailer Wiring Harness - Wishbone Style - 25' Ground Trailer End Connector 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 800-298-8924 for expert service.
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  • Reviews (39)
  • Q & A (8)
  • Videos (1)
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Optronics Wiring - A25W2GWB

  • Trailer Connectors
  • Trailer End Connector
  • 4 Flat
  • Plug and Lead
  • Optronics
  • 21 - 30 Feet Long

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:  4.8 out of 5 stars   (39 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

Just what I needed 697910

David A - 09/08/2020


- A25W2GWB

i like that its a double gound which will make it a stronger connection for the wiring to the lights 614869

- 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 737787

- A25W2GWB

Great idea having 25 foot ground wires instead of using the corroded trailer as a ground. Thanks. 914734

- A25W2GWB

Nice product. The "full" ground is worth it's weight in gold. Most lights on trailers fail at the grounding point which is usually the metal frame. With the full length ground wire you can make a complete circuit that will last much, much longer. Especially on boat trailers. 913376

- A25W2GWB


- A25W2GWB
by: 11/03/2020

Everything works as advertised, I use the harnesses to save time wiring sled decks. 907422

- A25W2GWB
by: 10/22/2020


- A25W2GWB

Used this to wire a folding, Harbor Freight trailer. They are notorious for being difficult to ground properly. Since this wire set has a separate ground running to each light, this was ideal for my needs. 895669

- A25W2GWB

ordered wiring harness and got the wrong one. called and received msg later that day that correct harness was on its way. i received the correct harness. thx etrailer! 869583

- A25W2GWB

First time customer and guarantee it won't be my last order. Package arrived early; is of excellent quality; and was a fair price. Installation was a breeze as well. Thanks for the good service! 866153

- A25W2GWB

Cured the problem I was having. 857819

- A25W2GWB

Excellent, got here in a timely manner, have not put on trailer yet, but will, when I do I will take pictures & send them, I have used wishbone wiring on a boat trailer before & this is the way to go 847333

- A25W2GWB

We just built a 35' trailer for a local screen company, needed some extra length for the tail light set & found etrailer and bought the harnesses, great delivery & price was very competitive, we will use them in the future, a good find- 844594

- A25W2GWB

Just what was needed. Worked perfectly and didnt require anything to restore my lights to functionality. 838077

- A25W2GWB

perfect 836907

- A25W2GWB

Good quality product connector is well made. Plenty of wire came for my installation (fairly short trailer) and instructions were clear. Still working after a year. 829799

- A25W2GWB

The harness was exactly what I was looking for 826438

- A25W2GWB

Easy to install and with ground did not to run extra wire for ground 823040

- A25W2GWB

Wiring harness was just as described, and shipping was very quick. Thanks 816175

- A25W2GWB

I was pleased that you provide a wiring harness with a full ground. But when I opened the box I was disappointed how small of a gauge the wiring is. I many stick with my home made ground wire and original 20 year old wiring. 815492

- 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. 809098

- A25W2GWB

It’s true these guys are that good 792140

- A25W2GWB

Great transaction! I’ve bought several items from etrailer and I’ve always gotten great quality products for a reasonable price! 783963

- A25W2GWB

My boat trailer lights were intermittently working, and upon investigation there were multiple ghetto splices all over. I decided to replace the entire harness, and found this one online at an awesome price! The product came exactly as advertised, great quality, and installation was a snap! 776648

Show More Reviews

Ask the Experts about this Optronics Wiring

  • 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...
  • 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...
  • 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...
  • 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...
  • 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...
  • 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...
  • 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...

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Info for this part was:

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

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