bing tracking image
  1. Trailer Wiring
  2. Optronics
  3. Trailer Connectors
  4. Trailer End Connector
  5. 4 Flat
  6. Plug and Lead
35 Ft 4-Way Trailer Wiring Harness - Wishbone Style - 42" Ground

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

Item # A35W42B
Retail:$25.47
Our Price: $20.92
You Save: 18%
Trailer Wiring
Shipping Weight: 1.18 lbs
Add to cart
In Stock
zoom in icon
slider vertical icon
zoom out icon
Comment field cannot be left empty.
Name field cannot be left empty.

Thank you! Your comment has been submitted successfully. You should be able to view your question/comment here within a few days.

Error submitting comment. Please try again momentarily.

Product Images

In Use/Installed

Customer Photos

Need help with installation?
Locate installers near me
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 etrailer.com or call 1-800-940-8924 for expert service.
  • All Info
  • Reviews (768)
  • Q & A (0)
  • Photos

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.


Features:

  • 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


Specs:

  • 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   (768 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.

by:

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.

Barry

5/7/2024

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



by:

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



by:

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.



by:

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



by:

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



by:

It all worked as advertised good instru ctions.



by:

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.



by:

Great product

Albert

3/1/2024

Still working great with no issues



by:

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!

Eric

1/29/2019

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.



by:

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



by:

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!!!!



by:

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.



by:

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.



by:

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



by:

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.



by:

Great Product!



by:

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!!!



by:

Product as described. Fast shipping



by:

Good wishbone wiring harness, decent ground eyelet, not tiny



by:

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



by:

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!



by:

Came on time long enough for 23' boat



by:

Excellent product and shipping!

Let
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.



by:

The wiring harness arrived quickly and was installed with ease.



by:

I am giving this item an Excellent review based on my former (very positive) experience with your products, but actually I haven't used it yet. My former harness is still working. I will use this as a replacement when the time comes.


25
768
Show More Reviews

See what our Experts say about this Optronics Trailer Wiring

  • How To Wire a 5th Wheel for Triple Towing a Trailer with Brakes
    It is possible to triple tow (1 tow vehicle + 2 trailers) when both trailer's have brakes but this would mean that the brake output wire that runs from the brake controller in the tow vehicle to both trailers would need to be at least a 6 gauge at the minimum so you don't have issues with voltage drop. Also, the number of braked axles cannot exceed what your brake controller is capable of handing which most are usually four. In order to obtain the needed length of 6 gauge or greater wire...
    view full answer...
  • Recommendation for New Wiring Harness on Vintage Trailer with Two Marker Lights
    If your vintage trailer isn't equipped with electric brakes and you only need to power those rear marker lights, then a 4-Way harness like the Optronics # A35W42B will work great. This is a wishbone style harness that features two wires for the running lights - one for the right side of the trailer and one for the left - which just makes wiring it up a lot easier. The harness itself features 35 feet of wire that you can cut if needed. I've attached an install video that you might also...
    view full answer...
  • Why Does My 4-Way Trailer Connector Have 5 Wires
    It sounds like your trailer has a 4-way wishbone connector like part # A35W42B. The connector is only 4 pins but there are 5 wires coming from it. The two brown wires are both for the running lights which makes it easier to install because you have two wires one to run down each side of the trailer. This way when you wire the trailer you don't need a jumper wire to go from one side to the other. If this is what your setup has then yes the two brown wires are connected to one pin on the...
    view full answer...
  • Trailer Tail Lights Flash with Passenger/Right Side Turn Signal
    The best way to troubleshooting your trailer wiring is by starting at the vehicle side with a circuit tester. I recommend running through each of the signals here with the circuit tester to make sure they are sending the correct signal when they are supposed to and not sending the signal when they are not. For example, if you have power on the trailer tail light pin when the right turn signal is active, you know the issue is on the vehicle. If the pin does not have power, work your way...
    view full answer...
  • How Do I Re-Wire My Pop-Up Trailer To A 4-Pole Trailer Connector? They
    In order to wire your pop-up trailer with a 4-pole wiring harness like the 35 Ft 4-Way Trailer Wiring Harness - Wishbone Style # A35W42B, you're going to first have to: 1. Connect the white ground wire to your trailer's frame. You'll want to make sure that the spot you choose for grounding is a clean, bare, surface that is free from rust. You'll use the already attached ring terminal, as well as a self-tapping screw # 101131802. Before you secure your ground wire, be sure to leave the...
    view full answer...
  • Replacement Wishbone Style Wiring Harness For Travel Trailer
    With you splicing the brown wire, on your current wiring harness on your trailer the harness it should work properly. It sounds that you have a bad ground or some damaged wiring somewhere along the trailer. I recommend installing the 35 Ft 4-Way Trailer Wiring Harness # A35W42B which will provide you with the wishbone style harness. This harness will come with two tail light wires split for simple wiring. This will allow you to run wires separately down each side of the trailer to the tail...
    view full answer...
  • How To Rewire Small 4-Way and Large 7-Way Trailers
    It sounds like you are either trying to wire a new trailer or rewire an old trailer. If that is the case then I do have options for you but I do not have any reference to an "elicit axle/trailer". In order to wire/rewire your trailer we will first need to determine how many powered circuits it has. The majority of smaller trailers will only have three powered circuits which are for left side stop/turn lights, right side stop/turn lights, and running lights. If this is all you have then...
    view full answer...
    Image 1 for
  • License Plate Recommendation for a Small Trailer Towed by Motorcycle
    Most likely yes, but you would have to check with your local DOT to confirm that. An easy light to use would be the part # LPL31CB. This would tie into the running light circuit of the trailer's lights and would light up the license plate.
    view full answer...
  • Replacement Trailer Connector on a Boat Trailer with a 4-Way Flat but 5 Wires
    You have what is called a wishbone harness. The running light circuit is split at the connector. This is so you do not have to run a jumper wire from the running light on one side over to the other side. For a replacement you can use # A35W42B. A wishbone harness will work just fine with a standard 4-Way flat harness on your vehicle.
    view full answer...
  • How to Wire a Trailer for Tail Lights
    First, lets make sure you have all of the parts you need to wire a trailer for lights. If you have an old trailer and want to replace everything, I recommend using a kit like our Optronics Tail Light Kit, # TL29BK and our trailer wiring installation kit # HM51020. We also have an LED kit, # TLL9RK. Step 1 - The trailer connector should extend 2 - 3 feet past the tongue. Attach the ground wire directly to the tongue of the trailer using a self tapping screw # 101131802 and a ring terminal...
    view full answer...
    Image 1 for Image 2 for
  • Troubleshooting Right Stop/Turn Circuit on Aluminum Trailer
    It sounds like you have narrowed the problem down to being somewhere on the right stop/turn circuit (green wire) on the trailer. If you can use your circuit tester to test that circuit as close to the light assembly as possible to see if the light is getting voltage or not. The other possible problem is that the ground of the assembly isn't sufficient. Make sure that the vehicle side and trailer side connectors are clean and free of corrosion inside and out. The main connector grounds...
    view full answer...
  • Determining What 4 Wires that Run to Trailer Hub are For
    You'll probably have to pull off the hub/drums to see where the wires go. It's most likely that your assemblies have two magnets and two of the wires are power and two are ground, one for each magnet, but since your configurations is not standard we'll have to look further into what's going on with the assemblies. Can you get me pictures possibly of the magnets? If you see two wires ran to each magnet you'll need to run a power circuit and a ground to each of them since they are not polarity...
    view full answer...
  • Rear Brakes On Trailer Grab More Than Front Brakes
    If the trailer is wired correctly then the front two and rear two breaks should receive about the same amount of voltage. If you test the brake output wires just before the magnets that will allow you to confirm this. If they have different voltage then you have any issue with your wiring. If the front and rear braking assemblies are both receiving the same amount of voltage then most likely the braking assemblies are not adjusted properly. If you have manual adjust assemblies then there...
    view full answer...
  • All Lights On Trailer Flash With Turn Signal Applied
    If you have five wires on your trailer with two browns, one for each side then you have a wishbone trailer wiring harness like the part # A35W42B. This harness will still only use four pins just like the 4-way on your vehicle trailer wiring harness because the two brown get tied together. In regard to the issue you are having with all lights flashing, this is most likely caused by a wire mix up therefore I recommend you check over both the trailer and vehicle side trailer wiring harnesses...
    view full answer...
  • Troubleshooting Trailer Wiring with 4 Pins but 5 Wires With Trailer Lights Not Working
    Thanks for the photo. The harness on your trailer is known as a wishbone harness and simply has the running lights split from side to side so you don't have a jump wire from one side of the trailer to the other. This allows a clean wiring from your trailer tongue to each tail light. Because you are able to get power from the vehicle but the trailer lights don't work, there is some simple troubleshooting you can do. First, I recommend cleaning the terminals on your trailer connector...
    view full answer...
    Image 1 for
  • Can a Trailer be Parked on a Driveway with an Incline
    Since your driveway is on an incline the trailer will have to have the wheels chocked so it can't roll. Or it will have to be coupled to a tow vehicle while it is parked. It is hard to beat a good rubber chock such as # 337WC1467A sold in quantities of 1.
    view full answer...
  • Brake Controller Recommendation For A 2020 Dynamax Isata 3
    For your 2020 Dynamax Isata 3, I recommend the Redarc TowPro Elite # RED44FR. This is a great proportional brake controller, that is low profile, and can be used on trailers up to 3 axles. When installed, only a control knob is exposed, getting rid of unnecessary bulk and creating a slick look. If you don't already have a 7 way # ETBC7, or a 4 pole # A35W42B, you'll need to add one first before installation.
    view full answer...
  • Troubleshooting Trailer Wiring That Stopped Working After a Year
    First thing you should do at this point is test the 4-way of the wiring harness with a circuit tester part # PTW2993 for voltage on all of the right pins when the taillight signals are being applied. Just like in the video I attached. If the voltage checks out there but the trailer lights still don't function right then the problem is on the trailer wiring. That would mean that problem is either due to a ground issue or a short issue. Make sure that the trailer side connector are clean...
    view full answer...
  • Why Does 4-Pin Trailer Wiring Have 5 Wires
    Your 4-pin/5-wire wiring harness is what is called a "wishbone" type which simply means that there are two separate running light wires, one brown and one pink. This allows a separate running light wire for each side of the trailer which saves you having to run a jumper wire from one side of the trailer to the other. We offer lots of wiring items just like this, such as # A35W42B, # A20WB and # A10-4225VP, which happen to use two brown wires instead of one brown and one pink. The functions...
    view full answer...
    Image 1 for
  • Troubleshooting Dim Blinking on Left Turn Signal When Right Turn Signal On
    More than likely this is a short in the trailer wiring or corrosion on your connector. Go ahead and inspect your connector on the trailer and vehicle side. If any corrosion is present, it is possible power is moving over causing both to run at the same time. One way or another it would be a good idea to clean both. After you check the connectors, go ahead and make sure your ground wire is secure. This is an easy thing to check and the source of many problems. Assuming your ground is in...
    view full answer...
  • Heavy Gauge Wiring For Lighting Functions on Trailer
    The 4 pole wiring harnesses we offer for trailers are pretty consistent when it comes to the wire gauge. The right turn/brake, left turn/brake and running lamp circuit wires are typically 18 gauge and the ground wire is typically 16 gauge. This is pretty much industry standard. However, the Hopkins Easy-Pull harness, part # HM38136 has a design that will eliminate the typical failure point of a 4 pole trailer harness, which is the point where the harness meets the plug. The plug features...
    view full answer...
  • How Many Wires are Typically Ran to Trailer that Only Uses Lighting Functions
    Typically you only need to run three/four wires for standard trailer lighting. One for running lights to each assembly and then two for each stop/turn light. Sometimes you have to run the ground wire to each assembly but typically they ground through the hardware and that's not needed. I attached a diagram that shows how trailers usually wire up. The style of connector usually installed on a trailer like yours is a 4-way flat like the part # A35W42B which comes with 42 inches of wire...
    view full answer...
    Image 1 for
  • Troubleshooting Trailer Wiring When Turn Signals Cause Marker Light to Blink and Both Tail Lights
    It sounds like your connection may have some corrosion or your splicing has allowed the jumping of power from one function to another. I recommend first checking your vehicle side connector using a circuit tester like # PTW2993 to determine if the functions are shorting on the vehicle side causing that issue. I've attached a video to assist. If the vehicle side wiring checks out, then it sounds like the color for color connection was not correct with the functions. The two brown wires...
    view full answer...
  • Why Wont a Cam Am Trailer for a Spyder Work with a Honda Goldwing
    Motorcycles typically have separate turn signals and brake light circuits. The Spyder might have combined brake lights and turn signals which could explain why the trailer made by the same company that makes the Spyder works with it and not the Honda. It could also be that there isn't enough load from the LED lights for the wiring harness on the Honda to recognize that something is drawing power. In this case you would need to add load resistors, # DI34ZR, on each affected circuit. They...
    view full answer...


< Previous
123. . .13



Do you have a question about this Trailer Wiring?


Info for this part was:

Employee Mike L
Expert Research:
Mike L
Employee Robert G
Expert Research:
Robert G
Employee Michael H
Expert Research:
Michael H
Employee Jameson C
Expert Research:
Jameson C
Employee John H
Expert Research:
John H
Employee Adam R
Expert Research:
Adam R
Employee Rachael H
Expert Research:
Rachael H
Employee Jeffrey L
Expert Research:
Jeffrey L
Employee Victoria B
Expert Research:
Victoria B
Employee Zack K
Video Edited:
Zack K
Employee Brian T
Updated by:
Brian T
Employee Carrie F
Updated by:
Carrie F
Employee Sabrina W
Updated by:
Sabrina W

At etrailer.com we provide the best information available about the products we sell. We take the quality of our information seriously so that you can get the right part the first time. Let us know if anything is missing or if you have any questions.