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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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Optronics Wiring - A35W42B
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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. 35 Ft 4-Way Trailer Wiring Harness - Wishbone Style - 42" Ground part number A35W42B can be ordered online at etrailer.com or call 800-298-8924 for expert service.
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Optronics Wiring - A35W42B

  • Trailer Connectors
  • Trailer End Connector
  • 4 Flat
  • Plug and Lead
  • Optronics
  • 31 Feet and Longer

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   (484 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:

What was needed to rewire boat trailer. 640879



- A35W42B
by:

Worth it's weight in gold when it came to wiring my trailer. I bought this for a homebuilt camper project and this made wiring my lighting simple. Although, my only complaint would be the short 42" ground wire. I'm a firm believer in not using the trailer frame for grounding - I consider it a sloppy installation practice. I'd rather run the extra wires and have dedicated ground wires run to all lighting 359697



- A35W42B
by:

Great product. Nice to have two running light wires (brown pin 2)so I could feed running lights and license light without splicing wires... 158701


Comments
Perfectly
Tom F - 10/31/2015

15741

- A35W42B
by:

Fast service and the product was just what I needed. Highly recommend this company and will buy from then again. 738470



- A35W42B
by:

Awesome products and superb service thank you 734208



- A35W42B
by:

Website was very helpful as to finding the correct part numbers. My order processed and was shipped in great time! This is my first time dealing with this company, but not my last. I’m recommending to all of my family and friends! 609437



- 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! 471215


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

49013

- A35W42B
by:

I recently bought a 2004 Trailstar boat trailer for a boat with a seized engine that a friend is giving me. The trailer was a great deal, but they told me the lights worked and they didn't. The connections were all corroded, none of the side lights were hooked up, and there wasn't enough slack in the existing harness to connect anything to it. Your harness was plenty long and only $15! I just wish that the ground wire was as long as the other wires. The ground wire only reached to the front part of the trailer and there's a hinge with rubber bushings halfway along the tongue. I had to ground the front part of the tongue to the part after the hinge. And then I used the ground wire in the old harness to ground the taillights. 619248



- A35W42B
by:

Harness was exactly what I needed and wanted. Most try to use a 4 wire system (which will do) and then split the running lite wire. 8 times out of 10 they can't get it right and end up taking it somewhere for fitting. etrailer.com had the exact item. Life is good again. quick shipping too. 615822



- 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. 497941



- 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. 146168



- A35W42B
by:

I am very satisfied with my experience with etrailer. The parts I received appear to be very good quality. I have not installed them yet though as I am waiting on Hurricane Michael to pass through. However the lights do seem to be very solidly built. I needed this style and etrailer was the one that had it. 572964



- 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!!!! 210017



- A35W42B
by:

I am a fleet manager and have used etrailer.com exclusively for all of my trailer parts needs for repair and maintenance for many years now. They literally have everything I have ever needed and the price is right. 898740



- A35W42B
by:

Great product, fast shipping!!! 897022



- A35W42B
by:

excellent product. this loom split so you can run 2 wires on rt side of trailer and 2 wires on lt side of trailer works out well. good quality loom and pigtail would definitely recommend this 894793



- A35W42B
by:

Still perfect after a year of use on my car hauler! 892336



- A35W42B
by:

Nice, really like the wishbone effect having a taillight wire on both sides of the trailer for the marker lights. 892263



- A35W42B
by:

Product arrived quickly. Have not installed yet. 881854



- A35W42B
by:

top shelf 876970



- A35W42B
by:

Product as described. Arrived a day ear ly. 873964



- A35W42B
by:

Delivered as scheduled; No issues with quality of product; Installed with no issues. 873598



- A35W42B
by:

870405



- A35W42B
by:

Plenty of sturdy wiring for my hauling trailer. 865932



- A35W42B
by:

Works fine 862752


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484
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Ask the Experts about this Optronics Wiring

  • What is the Wire Gauge on 10 Inch Electric Trailer Brake Magnets
    The magnet wires on Electric Trailer Brake Assembly # A35W42B are 18 gauge. The wiring going to the brakes from a trailer connector is usually larger such as 10 gauge # 10-2-1.
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  • How to Extend Short Ground Wire on 4-Pole Wishbone Harness
    Wishbone 4-pole harnesses like # A35W42B, # A20WB, # W002230 and # A10-4225VP usually do have a short ground wire because most trailer frames are steel and they conduct well enough that a ground wire attached near the tongue will provide sufficient ground even for lights mounted all the way at the back of the trailer. On the other hand if you have an aluminum frame trailer that does NOT conduct electricity nearly as well as a steel frame then you might need to extend that 2- or 3-foot...
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  • Recommended Wishbone Wiring Harness to Rewire Trailer with Surge Brakes
    Rewiring your trailer is something that you can absolutely do easily and there are harnesses called wishbone harnesses that don't require any wiring across the trailer frame. I recommend the 35 ft. Wishbone 4-Way Trailer Wiring Harness with 42" Ground Wire # A35W42B. I've attached a review video as well as an installation video to assist. I've also attached an article on wiring to assist with diagrams. If you have the electric reverse lockout on your trailer coupler, you may want the...
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  • 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...
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  • Trailer Wiring Connector for Triton 8x10 Aluminum Snowmobile Trailer
    For your wiring, you will need to test your wire functions to know which one connects where. I recommend using a 12v battery and simply connecting the negative terminal to the trailer frame and then connecting the power to each wire at the connector individually to determine function. It is not uncommon to have two wires running to one function location for each side of the trailer so there aren't any jumper wires across the frame needed from side to side. I've attached an article...
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  • Do the Ground and Power Wires From First Brake Need to Go to the Same Wires on Second Brake
    Great question! For the second brake it does not matter which one is connected to your 12V power and which is connected to ground. Just like on the first brake that gets spliced into the main 7-way wiring, the wires on the second brake are interchangeable. One should be connected to power and the other to ground.
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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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  • Recommended Trailer WIring for 4-Way Flat, 5-Way Flat, 6-Way Round, and 7-Way
    For a Trailer Wire Harness I recommend the following options: For a 4-way Trailer Harness use # A35W42B. This is a wishbone harness so it has wiring to each side of the trailer separately. Likewise for a 5-way wiring harness use # A40W5B. For a 6-way, I recommend using a junction box like # 38656 with Connector and Lead Wire # H20036 For a 7-way, I recommend # e99011. The remaining wires will use # 12-2-1 or # 12-1-1 sold by the foot. I've attached an article to assist.
    view full answer...
  • Troubleshooting Trailer Brakes Where Only One Assembly Locks Up
    The brake assemblies all will receive the same amount of power from your brake controller so the issue is the brake assembly that is locking up. Most likely it's adjusted tighter than the others which is causing it to lock up sooner. That would be the first thing I'd check. The trailer wheels should be able to turn by hand if they are off the ground but you should be able to hear the brakes drag on the drum slightly. Check to see if the one that locks up is harder to turn and that would...
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  • 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...
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  • Gauge of Wiring in 35 Ft 4-Way Trailer Wiring Harness # A35W42B
    The gauge of the wiring in the 4-way kit part # A35W42B is 18 gauge.
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  • 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...
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  • Troubleshooting a 4-Way Wishbone Trailer Connector Without Running Lights
    Traditionally, the brown wire is the running lights. On your trailer you have a 4-way wishbone connector, similar to our part # A35W42B. With a wishbone the running light circuit is ran on two wires one going to each side of the trailer. This usually makes wiring the trailer easier. Do you have running lights at the vehicle's connector? Use a circuit tester, like part # 40376, to test each function on the back of your tow vehicle. This will isolate whether the problem is with the...
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  • Replacement Trailer Side 4-Way Flat Wishbone Trailer Connector
    It sounds like you need a replacement 4-Way wishbone trailer side connector like # A35W42B. It is a 4-Way harness but has 5 wires, 2 of which are for running lights. I have included a link to a video showing a typical wiring and light replacement for you. If you need to plug a 4-Way flat trailer side connector into a 5-Way flat on a vehicle, normally you will not need an adapter because a 4-Way can plug into a 5-Way most of the time. If you are actually looking for something else let...
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  • What is Wire Gauge of Optronics 4-Way part # A35W42B
    All of the wires in the Optronics 4-way wiring harness part # A35W42B are 20 gauge.
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  • Tracking Down Possible Poor Ground Connection on Travel Trailer
    What you're describing is the classic symptom of a poor ground connection somewhere in your trailer lighting system. When all the functions are being used, you're drawing maximum amperage through the system, which is when a ground problem will manifest itself. Trace the white ground wire back from the trailer connector. The wire will usually ground to the trailer frame somewhere on the trailer tongue. Make sure this connection is secure and not corroded. Each trailer lamp will also have...
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  • 4-Way and Harness Recommendation for Rewiring a 4-Way on a Trailer
    Sounds like you are trying to replace the 4-way and wiring of your pop up trailer. The Wishbone 4-Way Trailer Wiring Harness, part # A35W42B would work perfectly for you. The wire for the running light circuit is actually split into two wires, one to run down each side of the trailer. This harness comes with 35 feet of harness to run to each assembly. You would just need to remove the excess wire before connecting to the assembly. I attached an install video for you to check out...
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  • Replacement 4 Way Wiring Harness for Yacht Club Snowmobile Trailer
    You're on the right track! If you're wanting to install a new 4 way connector on your snowmobile trailer you can use the 35-ft 4 way Trailer Wiring Harness # A35W42B. This is a wishbone style harness that comes with the tail light wiring already split up to allow you to more easily run the wires down the sides of the trailer to the lights. This wiring harness has 35-ft of wiring to accommodate even the longest trailers and can be trimmed down as needed to accommodate for shorter trailers....
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  • Can 12 Volt Brake Controller Operate 6 Volt Brakes
    You must have a vintage Airstream or something with old Warner electric brakes. Technically you could adjust the output voltage on any brake controller down to 6 or fewer volts (by adjusting the gain or power output knob) and it will work with the 6 volt brakes that you have without having to add any additional parts or a separate voltage regulator. There isn't a brake controller that is set up to work directly with 6 volt brakes and using a 12 volt controller will not harm the...
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  • How Does the 35 Foot Wishbone 4-Way Trailer Wiring Harness # A35W42B Function
    The way that the 35 foot Wishbone 4-Way Trailer Wiring Harness, # A35W42B, works is instead of having 1 taillight wire (brown) that you would need to splice into in order to run to both taillights, this harness has two wires (one attached to each stop/turn signal wire). The wires are attached to each other (except at the 4-Way connector) so you cannot mix them up. This would be good for your application since you will not have to splice wires that could end up being exposed to the water....
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    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...
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    The longest 4-way harness we offer that has all 16 gauge wire is the Wesbar Harness part # W787274 which is 14 feet long. For one that is 30 feet long that has a 16 gauge ground wire and 18 gauge signal wires you would want the part # W002230.
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    It sounds like you are using a wishbone harness to re-wire your trailer. A wishbone connector has a brown/green wire for the running lights on the right side and a yellow/brown wire for the left side running lights. You will also have a yellow wire that is for the turn signal and brake lights on the left side, and a green wire that is for the right side turn signal and brake lights. The white wire, as you mentioned, is for ground. On your trailer lights, most likely the red wire is...
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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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    A 4-way trailer wiring harness wouldn't carry a brake signal so it wouldn't matter how many axles you would have on a trailer that has a 4-way. A better option would be a 7-way as that style of harness does carry the brake signal. Starting with a trailer side 7-Way connector you can use # H20042 which is 3 feet long. It doesn't have to be long though because it is going to the junction box. Speaking of junction boxes you can use # 38656. I have included a picture showing how it...
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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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  • How To Wire A 7-Way Trailer Connector With A Wishbone Trailer Wiring Harness
    The best way to wire a 7-way plug on your trailer that has a 4-way wishbone harness is to use a junction box like part # 38656 from Spectro. The wishbone harness has two separate running light brown that connect both sides of the trailer running lights without the need to run a jumper wire between the two sides of the trailer. The # 38656 junction box will give you a nice way to wire together the trailer's leads and the 7-way plug like Hopkins part # H20044. You would use the junction...
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    You're on the right track, but the easiest and probably most secure way to run your ground circuit is to simply use the trailer frame for the ground. Ground your white wire to the trailer tongue as it comes off the trailer connector. Just use a ring terminal attached to the trailer tongue with a self tapping screw. Make sure the metal surface where you drive the screw in is clean bare metal. Each lamp will ground to the trailer frame either by a dedicated ground wire (it'll depend on...
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