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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

Item # A35W42B
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Trailer Wiring A35W42B - 31 Feet and Longer - Optronics
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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 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 800-298-1624 for expert service.
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  • Reviews (605)
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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.


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


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

Alternate part number: A-35W42B




California residents: click here



Customer Reviews

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

Average Customer Rating:  4.9 out of 5 stars   (605 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.

- A35W42B
by:

I ended up doing some metal work installed new leaf pins/bushing on that trailer, sandblasted, new paint/deck. so just installed about a month ago and works great . Quality wire should last. Thanks as always.



- A35W42B
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.



- A35W42B
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!


Comments
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.
Eric - 01/29/2019



- A35W42B
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.



- A35W42B
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!!!!



- A35W42B
by:

I have purchased twice for 2 separate boat trailers from etrailer. If you utilize a flat 4 plug as I do, they are a must. The harness coils nicely with ample extension. The harness is well built as is the majority I purchase from etrailer.



- A35W42B
by:

I purchased this to update my very old and non-functioning pontoon trailer wiring. I needed the extra length and was glad etrailer provided it as an option. Since the new wiring harness was already set up to run each side separately, it made easy work of rewiring the trailer. I really like etrailer products. I think they are of good quality for a good price. Sorry, no photos of the job.


Comments
Working like a charm. Still happy with the product and the outcome.
Lauri - 05/18/2021


- A35W42B
by:

Good quality products, and very fast shipping. I have trusted e-trailer with past purchases as well. This order included led tail lights and wire harness for my pontoon trailer. I needed a 35 foot harness and e-trailer had it. They are very difficult to find. And the lights and wiring was first class. Also e-trailer provides good videos for product instructions. Great company.


Comments
Trailer lights are working great. Being led and submersible is just what I need.
Steve - 10/09/2020


- A35W42B
by: 03/08/2021

Good quality, inexpensive


Comments
Excellent
Scrapper - 03/08/2022


- A35W42B
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.



- A35W42B
by:

I ordered the 4 way trailer end plug/wiring assy (35 Ft 4-Way Trailer Wiring Harness - Wishbone Style - 42" Ground Item # A35W42B), and it was at my house in about 3 days! And at a great price to boot!! I checked around all of the local auto parts stores, and none even had this product on hand! I'm bypassing the local stores now when J can, and ordering strictly from etrailer. Their prices are great, product selection is beyond any others I've seen. And their professional and informed people never fail to follow up with a complimentary email to make sure everything is to my satisfaction. If you're looking for towing-related items, look no farther than etrailer!!



- A35W42B
by:

Package arrived early, exactly what I ordered and in perfect condition.


Comments
Product continues to work as expected.
Dean - 03/01/2022


- A35W42B
by:

The wiring harness worked great.the extra length made it easier to install without splicing the wires



- A35W42B
by:

Just received it in the mail yesterday. Appears to be what I expected. If the wire proves to be good then all is as it should be.



- A35W42B
by:

Excellent product and would buy again!!



- A35W42B
by:

Good price reasonable quality This wiring harness has worked well since I installed it about an year ago



- A35W42B
by:

I have not received my order


Comments
I will have our Customer Service team reach out to you.
-- Etrailer Expert Jenny N - 04/08/2022


- A35W42B
by:

Exact What I needed. It worked great.


Comments
I sold the trailer the other day. Lights were still working fine.
Scott - 02/22/2022


- A35W42B
by:

Wires installed easy and worked for a couple of months. After getting the boat ready this spring I noticed that despite using watertight shrink wrapped and liquid electrical tape sealed connections the wires had completely corroded and now need to rewire the trailer all over again.



- A35W42B
by:

Good product, but was apparently out of stock, with long lead time. Offered an acceptable replacement, but before shipping called to say that they found a supply of the original part and made sure they shipped what was originally ordered. Good communication from the company throughout the process.



- A35W42B
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!



- A35W42B
by:

For a first time user of your products I am very impressed. You will be my 1st stop for my future trailer needs.



- A35W42B
by:

everytime i have bought from etrailer i have gotten good quality parts and a good price everything is wrapped up and boxed well will contact etrailer next time we need trailer parts thanks again mike red ryder ranch



- A35W42B
by:

Exactly what I needed to replace deteriorating wiring for trailer.



- A35W42B
by:

Good products and fast shipping.


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Show More Reviews

Ask the Experts about this Optronics Trailer Wiring



  • 40' Wishbone Trailer Wiring With A Ground Wire Running Down Both Sides
    We do not offer wishbone wiring that has a ground wire going down both sides. You really don't need it because the ground wire is for the plug itself not the lights and you want the ground close to the plug. I recommend using the 4-Way Wishbone Trailer Wiring Harness Item # A40W42B.
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  • Wiring Stop Turn and Tail Light Circuits to a Trailer Light
    Your trailer lights should only have one wire if the light serves only one function (tail light, marker light, stop/turn). The white wire shown in the photo that you attached is a ground wire and will not be connected to the tail light or stop/turn circuits. The bulb attached to your light housing looks like an 1157 bulb, which is a dual filament bulb that has two contacts for two different circuits. You should have two wires on the back of the light housing, one for the stop/turn circuit...
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  • What Wire Gauge is Used on the 35 ft. Wishbone 4-Way Trailer Wiring Harness, # A35W42B
    I went out to the warehouse and pulled a 35 ft. Wishbone 4-Way Trailer Wiring Harness, # A35W42B, and used a wire gauge tool to measure the wires. The copper wire itself is 20 gauge. If you measure the wire with the insulation on it then it is thicker but wire gauge corresponds to the strands not the insulation part.
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  • All Trailer Lights Blink With Turn Signal on 2007 Triton ATV Trailer
    The fact that you have an aluminum trailer could be the problem. Aluminum does not make for a good ground. What I recommend is to located the ground wires at the backs of the lights and attach jumpers from the grounds to the main trailer connector ground. This is a common issue with aluminum frames, tilt trailers, and trailers with folding tongues. Also check the towing vehicle and trailer connectors for dirt and corrosion. Corrosion could cause a short or even a bad ground as well. The...
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  • Wiring Brakes On Tandem Axle Trailer
    Typically trailer wiring is color coded. The brake circuit is usually a blue wire which travels to each brake magnet, where it is attached to one wire from each brake magnet. The other wire from each brake magnet will ground to the trailer frame. I have attached a drawing that shows how the wiring is typically run for brakes on a trailer. I have also attached a link to trailer wiring diagrams that may help.
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  • Wire Gauge Used for Wishbone 4-Way Trailer Wiring Harness # A35W42B
    On the Wishbone 4-Way Trailer Wiring Harness # A35W42B each wire is 20 gauge. It doesn't seem like much but it is more than enough for basic trailer light functions (stop, tail, turn, and running lights). I have linked a video featuring this product for you.
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    Electric trailer brakes have electro-magnets and they will need to be connected to the 7-Way trailer connector in order to receiver power from the brake controller in your Ford F-350. Since your truck is already set up with a brake controller and trailer connector we need to just focus on the trailer side. On your brake magnets one of the wires will be the power wire and the other will be the ground. It does not matter which is which. The ground wires should be attached to clean and corrosion...
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  • Availability of 40 inch + Long Wishbone 4-Way Trailer Wiring Connector
    Sounds like you are in need of a wishbone 4-way harness to replace what you have on your trailer. The two wires that run to the one pin are the running lights. We have a 42 inch long version of what you need, part # A35W42B. This is the longest harness we offer.
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    Many lights will list the wire functions on the back where the wires enter the light housing. If the functions are not listed it is likely that black is the ground wire and will attach to the trailer frame. The yellow wire would then be the power wire. Since it is a marker light the yellow wire would connect to the running light wire on the trailer. On a harness such as # A35W42B it wood be one of the wires with a brown stripe.
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    Sounds like you are wiring the brake output circuit from your brake assemblies to a pin on the junction box that carries the 12 volt circuit and not the brake output circuit. You need to make sure that you have the right circuit for the brakes on the junction box.
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  • Can Electric Trailer Brakes Ground Through Aluminum Trailer Frame
    Typically for aluminum frame trailers we recommend running the ground wire of each assembly all the way back to the main ground harness of the trailer up by the coupler as aluminum does not conduct electricity well and doesn't always work well for brake grounds.
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    Yes, you can jump the front axles brake output circuit to power the rear axle. Check out the picture I attached to see how most people do this.
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  • 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...
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    It sounds like the magnets or their wiring could be bad. Your 2012 Chevy Silverado 2500HD is probably sensing the wrong resistance from the trailer brake magnets and that is why you see that warning message. When magnets have 2 of the same color wire it usually means that you can use either one for either function. The black wire with the 12 volt power should not be attached to the brakes. Only the blue wire should connect to the brakes. The other magnet wire should be attached to the...
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  • Installing a Trailer Wiring Harness on a Trailer with Yellow, Black and White Tail Light Wires
    When it comes to tail light wiring, black is usually the running light circuit and white is usually ground. That would leave the yellow wire for the brake light and turn signal. On trailers, the turn signal and brake lights are combined on the same circuit. When installing a harness like the Optronics Wishbone 4-way Harness, # A35W42B, the green wire would connect to the yellow wire on the passenger side tail light and the brown wire with the green stripe would connect to the black wire...
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  • Converting 7-Way Blade To 4-Way Flat On Trailer
    Yes, it is possible to convert your 7-way on your trailer to a 4-way. To replace the wiring on your Coleman 10 Foot pop up camper we offer wiring adapters that allow connection of different formats of trailer wiring. The best option to change the wiring on your trailer to match the 4-Flat on your Xterra is to cut off the 7-Way blade, and then install (them in) a trailer side 4-Way # A35W42B. The right turn function is the GREEN wire, the left turn function is the YELLOW wire, The trailer's...
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  • Where Does Red Wire of 4-Way # 62990 Wire To on Trailer
    While we do not carry the 4-way kit part number 62990 I can tell you how it wires up. Basically the harness is a wishbone 4-way which has two wires for the running light circuit. One for each side of the trailer. The red wire goes to one side of the trailer's running lights and the brown goes to the other. Doesn't matter which side you pick. We have a similar wishboned 4-way wiring harness as part # A35W42B.
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    Yes, you can tie all of the ground wires for your trailer lights to a single point of connection. We actually recommend this as it can sometimes cut down on the amount of issues and the time it takes to troubleshoot faulty lights. Please be sure that the ground you are using is suitable which means it is a bare metal surface. If you need any lights or wiring connectors for your trailer then take a look at the attached selection I have included for you which has many options for you to...
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    There is not a standard wire color to function chart on a trailer for anyone to abide by so it will be best to test for function with a circuit tester. In order to check this all you need to do is start the vehicle, plug the trailer connector in, and test each of the wires while the corresponding signal is activated. The light should then specify which wire is for which function but you will again need to test the trailer wiring to determine which color wire has which function. Unfortunately,...
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  • How To Convert A Wishbone Trailer Wiring Harness To A Regular 4-Flat Trailer Wiring Harness
    It sounds like you have a wishbone wiring harness install on your trailer. A regular 4-way wiring harness has 4 wires from the back of the connector, 1 for left turn/brake typically (yellow), 1 for the right turn/brake typically (green), 1 for the tail lights typically (brown), and 1 for the ground typically (white). A wishbone 4-way connector has 5 wires, 1 for left turn/brake typically (yellow), 1 for the right turn/brake typically (green), 2 for the tail lights typically (brown w/ yellow...
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  • Tip for Wiring up Trailer 4-Way by Function
    The standard way a 4-way gets wired is the jacketed pin is the ground (normally white) the next one to it is the running light circuit and is normally brown, next to it is the left turn/stop circuit and is normally yellow, and finally the last pin is the right turn/stop circuit which is normally green. You are going to have to wire your setup by function.
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  • Trailer Wiring Replacement Recommendation for Trailer that Has 4-Way and 5 Wires
    Sounds like your trailer has a wishbone 4-way installed on it which means that two of the wires go to the same circuit (running lights) and the rest run to individual pins of the 4-way. For that we have the part # A35W42B which is 35 feet of wishbones 4-way for you to use to replace what you have. The two brown wires run to both of the running light pins of the connector you have. Then the rest wire where they need to go. If you are unsure where each circuit goes on your trailer's wiring...
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    If you need to replace the 4-way of your trailer you wouldn't have to track down where the harness runs. Easiest way would be to cut off the 4-way and wire in the new one. For that we have the part # A35W42B.
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  • Installing a New Trailer Connector that has 2 Brown Wires on a Trailer
    It sounds to me like you have a wishbone wiring harness on your trailer similar to part # A35W42B. Your trailer may not have a 4-way but the concept is the same. The brown wire is traditionally the running light circuit and a wishbone harness has two of them so that one can be run down one side of the trailer and the other down the other side. It keeps you from having to jump the running light circuit across the trailer somewhere. If I'm misunderstanding something and this doesn't help...
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