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35 Ft 4-Way Trailer Wiring Harness - Wishbone Style - 42" Ground

35 Ft 4-Way Trailer Wiring Harness - Wishbone Style - 42" Ground

Part Number: A35W42B
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Trailer Wiring
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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. 35 Ft 4-Way Trailer Wiring Harness - Wishbone Style - 42" Ground part number A35W42B can be ordered online at or call 1-800-940-8924 for expert service.
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Optronics Trailer Wiring - A35W42B

  • Trailer Connectors
  • Trailer End Connector
  • 4 Flat
  • Plug and Lead
  • 31 Feet and Longer
  • 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: 35'
  • Ground wire length: 42"
  • 3-Year Warranty

Manufacturer Cross Reference
Harness will work as an exact replacement for:

  • Truck Lite # 108835
Wishbone Wiring Diagram

A35W42B Optronics 35 ft. Wishbone 4-Way Trailer Wiring Harness with 42" Ground Wire

Alternate part number: A-35W42B

California residents: click here

Customer Satisfaction Score:

Customer Reviews

35 Ft 4-Way Trailer Wiring Harness - Wishbone Style - 42" Ground - A35W42B

Average Customer Rating:  4.8 out of 5 stars   (774 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.


2 things. 1st@: I think there should be an option to pick tinned wire. 2nd: The ring terminal for the ground needs to be bigger.



Works as it should.


Replaced the wiring and lights on my 1992 boat trailer. I was able to get everything needed from etrailer. I think Optronics is of the highest quality
and recommend both etrailer and Optronics product.



After a year of use the replacement lights and wiring has had no issues.


Arrived on time. Should be easy to wire my boat trailer with this wish bone split wire harness


Solid product, easy to install. Video was a great help.


Excellent service!! I was contacted by George at etrailer to tell me they had an alternate product in stock that would ship out immediately. Receive product a week earlier than expected!


Works very well after re-wiring trailer lights with waterproof distribution box.


I want to thank you for all your help with my trailer you were more helpful than you realize. So this is my trailer for a 22' Flats Cat shallow draft Catamaran. I totally dismantled my trailer and buffed by hand with a wire buffer and sand blasted in some spots and applied multiple coats of some very expensive galvanize paint (Z.R.C.). I installed all new C. E. Smith Carpet (about 80'), seven new LED waterproof lights, new springs, new equalizers, new tongue jack, new wench, new safety chain, new chain brackets, all new SS hardware and a 35' long wiring harness.
I was able to send only one review with a picture of the safety chain and brackets. I'm having a little trouble with the rest..oh some of these items were bought locally or from your competitors, until I found ETRAILER. Your prices were cheaper for the exact same things. Your helpful how to videos were helpful. And Rose, your personal helpful knowledge made my buying experience very pleasant, I actually enjoyed talking to you! Thanks to ETRAILER and specifically to Rose G.


Made it easy to rewire old 16 foot trailers with extra wire to reroute it better.


The plug looks and feels solid! This is the only place that had a long enough wiring harness to do what I needed. Shipping was also very fast!



After one year, It is still working great! It makes all the difference having long enough wires to where there is no splicing on a saltwater boat trailer.


Item as describe. Work Fantastic!!!!!!! !!!!!!!


Perfect! Just what I needed!!
I could
only find a harness plug with one brown wire (4 wires total) at my local stores. I "googled" the problem I had (my harness plug had 2 brown wires). A rep from etrailer had answered someone's same question on a message board. It was a detailed explanation as to why one would need this part. Then the rep put a link to the etrailer site. And there is was, the harness plug with 2 brown wires (5 wires total) and at an agreeable price to boot!!!!! And now I know about the etrailer website!!!!


It all worked as advertised good instru ctions.


This worked great, had to rewire my trailer after having it painted and reconfigured and this item was long enough and allowed me to tie in my additional lights.


Great product



Still working great with no issues


items are exactly as shown on website. I made a phone call to clarify if my application suited the part. Friendly knowledgeable Shipping price & delivery excellent


Absolutely Fabulous! Exactly what I was looking for but couldn't find at any retail store in my area! The wishbone design splits the brown wire at the plug. Makes wiring both sides of the trailer with no splices or having to find additional brown wire sold by the foot!


Worked out great. Direct replacement for my old 4-way boat trailer harness that had corrosion damage at a quick splice joint causing my trailer marker lights to not work. Easy to follow wiring diagram from etrailer store page.


Reasonably priced and delivered before promised. It's exactly what I need.


Great product very easy to install my order arrived 3 days early I received emails so I was informed when my wiring harness was shipped and one when it was delivered Thanks E Trailer A happy customer!!!


A quality wiring harness, plenty long enough for my boat trailer.


1 year, and so far so good. I have had cheap harnesses before that would oxidise from the inside out and break when connecting flat 4, but this one is doing fine.


Good wishbone wiring harness, decent ground eyelet, not tiny


Great Product!


Excellent product and shipping!

me say all I could find everywhere was 25 ft. The extra 10 feet I get with this item NOW allows me to fix the short in my utility trailer.

Thank you so much.


Product as described. Fast shipping

Show More Reviews

See what our Experts say about this Optronics Trailer Wiring

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