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5-Flat Vehicle End 72" Wiring Harness

5-Flat Vehicle End 72" Wiring Harness

Item # 20016
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Wesbar Vehicle End Connector Trailer Wiring - 20016
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The 5 way flat trailer connector is most commonly found on boat trailers that have hydraulic brakes. The fifth wire is hooked up to the reverse light circuit on the vehicle which then sends a signal to the hydraulic coupler to disengage the trailer brak es. Lowest Prices for the best trailer wiring from Wesbar. 5-Flat Vehicle End 72" Wiring Harness part number 20016 can be ordered online at or call 1-636-306-4830 for expert service.
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Wesbar Trailer Wiring - 20016

  • Trailer Connectors
  • Vehicle End Connector
  • 5 Flat
  • Plug and Lead
  • 6 - 10 Feet Long
  • Wesbar

The 5 way flat trailer connector is most commonly found on boat trailers that have hydraulic brakes. The fifth wire is hooked up to the reverse light circuit on the vehicle which then sends a signal to the hydraulic coupler to disengage the trailer brak es.

5-Flat electrical wiring connector

Fifth wire added for surge brake lockout circuit which is becoming more common on today's newer boat trailers.

5-Flat wiring Connector will still work with most 4-pole trailer connectors.

118016 5-Flat Vehicle End 72" Wiring Harness

California residents: click here

Video of 5-Flat Vehicle End 72" Wiring Harness

Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.

Video Transcript for Wesbar Wiring - Trailer Connectors - 20016 Review

Today, we're going to review part number 20016. This is the Wesbar 5-Flat Vehicle End 72 inch Wiring Harness. This harness can be used if you have a damaged 5-way on your vehicle or if you need to install a 5-way on the vehicle. Basically, a 5-way is usually on boat trailers that have hydraulic brakes. Basically, this extra blue 5th wire right here is hooked up to the reverse light circuit on the vehicle and then that sends a signal to the hydraulic coupler to disengage the brakes when you go into reverse. This 5-way flat connector will work with 4-ways also. Basically what you'll do is the center one is the ground.

You just start on this end, plug your 4-way in and it just wouldn't plug into the one on the very end here, the blue one right here. You could still use this with a 4-way also. The five wires right here, the white is your ground. This is the blue, which would be connected to your reverse light circuit. The three that are attached together are basically the brown is the tail lights, the yellow is the left turn and brake, and the green is the right turn and brake signal. Again, the length on this is 72 inches. That should do it for the review on part number 20016.

This is the Wesbar 5-Flat Vehicle End 72 inch Wiring Harness. .

Customer Reviews

5-Flat Vehicle End 72" Wiring Harness - 20016

Average Customer Rating:  4.8 out of 5 stars   (28 Customer Reviews)

The 5 way flat trailer connector is most commonly found on boat trailers that have hydraulic brakes. The fifth wire is hooked up to the reverse light circuit on the vehicle which then sends a signal to the hydraulic coupler to disengage the trailer brak es.


I purchased this set to rewire my race car trailer and add reverse lights to the pigtail... wiring went flawlessly and there was plenty of wire and connectors are good quality... even had a dog chew on the trailer end and other than a slight ground issue, works perfectly.


Works Great with my motorcycle trailer.


Don't know WHY this type of plug in IS so hard to find anywhere BUT HERE !!!!!!!!!!!!!! This place ( has WHATEVER ( almost ) one is UNABLE to find anywhere else ! Great selection of parts, great customer service, UNLIKE other places, that don't know the products they sell....VERY affordable prices, most times lower than OTHER places !!!!!!!!!!!!! Videos that take you step by step AND the graphic diagrams ! The people here ALWAYS have time to talk / explain to you on the phone how to solve a problem OR recommend a part you may NEED ! THIS company is UNLIKE any other, they are THE BEST from products to helping you out ! THANK YOU ALLLLLLLLLLLLL

Haven’t installed it yet
Jeff B - 10/23/2017


Very satisfied with this wiring harness. Needed to upgrade the old 4 pin harness on my 2007 Toyota FJ Cruiser. I need a 5 pin harness for my boat trailer, and the original 4 pin was corroded.
I also ordered the bracket for this harness, Item # tr20046, which worked great with this harness. You will also need to order a cover for this harness as it does not come with the protective cover.


I just bought my first boat trailer that had hydraulic brakes, and I didn't know how to 'make' them release when going in reverse. The dealer said I had to remember to flip a lever on the trailer-tongue each time, which would have been a hassle!

Then I found this product. It wires into my truck reverse-lights so that whenever I need to back up, the 5th wire (blue one) will automatically energize a solenoid on the trailer and release the trailer brakes. Yippeee!

A great product, good customer service, and FAST shipping!


Being a new boat owner I was quickly overwhelmed by what I didn't know. Re-wiring, re-lighting my trailer was my first project. etrailer has a wide range of products, but most important to me, was their added product information and instructional information which helped me make the right selections to get this done. Add to that is their very competitive prices. etrailer will be my go to source for my future trailer needs.


Kind of disappointed in this wiring kit,.
wire gauge is very small, I had perchased a second wire kit from the discount hardware store made by Kenway but ordered this one thinking it would be better, it was not. The wire including the insulation on your kit is about the same size as the conductor with no insulation on the Kenway's. I will not be ordering wiring kits from here again.


I re-wired my boat trailer and up-dated my lights with these things.. great products worked better than I thought !


I needed a plug to adapt from a 4 pin wire + a loose wire to a 5 pin connector. worked like a charm.


Well made product and works great and fits as it should. I would tell anyone that they have quality products and excellent customer service . I have found a place for all my trailer needs, James DuBois


Top of the line product as is everything etrailer sells.

by: make this installation easy as 1 2 3.


This was the connector that I needed for my Goldwing to connect to my Cargo trailer.


This 5-way connector works great.


Must have for short bed truck owners


Item delivered very quick. I will purchase again from these guys.

Light bar working great. No issues.....
Mike V - 06/08/2017


Quick shipping, good product


As ordered quick shipping


Great stuff, good prices and one-stop shopping. I tried to source all of these items locally but was unsuccessful. Thanks!



Great Service, Great Communication, Fast Delivery - will purchase again!!!


Parts ordered were as advertised and received timely.


Have not tried yet just got it lastnight


Good product. Does the job.


Just what I was looking for at a good p rice.

Show More Reviews

See what our Experts say about this Wesbar Trailer Wiring

  • Which Circuit Runs to Blue Wire of Trailer Wiring
    Your trailer wire that is blue would be for the trailer brakes so the truck blue wire that is labeled electric brakes would be the correct one to use. Not every trailer has the need for a reverse light circuit.
    view full answer...
  • Troubleshooting Trailer that Applies Brakes When Vehicle is Put In Reverse
    It sounds like there is a short on the trailer side of the wiring. It sounds like the reverse light circuit is touching the brake output circuit which is causing the trailer brakes to apply when you put the vehicle in reverse. Check the connector on the trailer for corrosion and clean as necessary. Next check the wiring of the trailer connector as it leads back to the trailer. Most likely there is cut or exposed wire that is causing the short. I also attached a help article that has trailer...
    view full answer...
  • What Gauge Wire Does The Wesbar # 20016 5-Pole Vehicle End Trailer Connector Use
    The Wesbar # 20016 5-Pole Flat Vehicle End you referred to uses 18 gauge wire. The yellow wire carries the left turn signal/brake lamp, the green carries the right turn/brake lamp, the brown carries the running light signal, the white wire carries the ground and the blue wire is connected to the reverse light circuit on the vehicle which then sends a signal to the hydraulic coupler to disengage the trailer brakes, so the vehicle can back without actuating the surge brakes.
    view full answer...
  • Should Trailer Running Light Circuit Run to Both Taillight Assemblies on a Trailer
    Most likely yes. The brown wire coming from the vehicle should be the running light circuit like you mentioned and the running light circuit of your trailer will most likely be a brown wire that also runs to the taillight housing on the trailer. The brown wire will need to go to both sides of the trailer's taillights to carry this circuit to both lights.
    view full answer...
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  • Does Brown on Trailer Wiring Indicate Running Light Circuit
    Most likely the trailer light wiring you have on your trailer that have brown on them are for the running light circuit and the ones with red are for stop/turn circuits. Your best option is to test the wires with a circuit tester like part # 3808 while a buddy applies the trailer light functions and then wire your trailer accordingly.
    view full answer...
  • Troubleshooting Dim Trailer Lights on Boat Trailer When Head Lights Are On
    The problem is either that you have a bad ground or the charging system or your truck is just at it's capacity from having every light activated on the vehicle. Most likely it is the trailer ground though. Since a lot of trailers will actually ground through the coupler of the trailer to the hitch ball, and then to the vehicle's hitch frame, trailer lights will still typically function with the ground strap removed of the trailer connector. What I would recommend you try next is run a...
    view full answer...
  • Troubleshooting Why Trailer Lights Go Out When You Hit the Brakes
    It sounds to me like you may have a ground problem. There are several places to look for a poor ground connection. I recommend starting with the trailer connector on the trailer. Check to make sure that the ground wire is secured to a clean metal surface on the trailer. In addition, each lamp/signal will also need to be grounded. Typically the lamp/signal is grounded through the mounting bolts having direct contact with the trailer frame. If the area that the lights are mounted to is...
    view full answer...
  • What are the Functions of Trailer Light Green, Yellow, and Brown Wires
    Normally, the green wire on the right side carries right turn signal and brake light functions and the brown wire carries running light functions. On the left side, the yellow wire carries left turn and brake lights and the brown wire again carries the running lights. With only 2 wires, these lights must ground through the mounting studs. Make sure to wire in the new lights by function to the existing trailer wiring and not by color.
    view full answer...
  • Trailer Lights Only Work with Camper Plugged In To Shore Power
    It sounds like the trailer lights are tied into the interior lights and the trailer mounted battery and inverter. What I recommend is to have the trailer exterior lights bypass the rest of the wiring so that the trailer connector is isolated from the other lights. It seems that if everything is connected together through the battery or the inverter, including the trailer connector. Replacing the battery could solve the issue but I would still have the trailer connector separate from the...
    view full answer...
  • Identifying Circuits on Possible Wishbone Trailer Connector
    What you are describing sounds like a wishbone harness. A wishbone harness splits the running light circuit into two wires coming directly out of the 4-pole connector.Instead of a single brown wire carrying the running light circuit, you would have a brown/green wire for running lights on the right side of the trailer and a brown/yellow wire for left side running lights. You would also have a yellow wire carrying the left turn/brake light circuit, a green wire for right turn and brake,...
    view full answer...
  • Trailer Wiring Diagram for 4-Way, 5-way, 6-Way and 7-Way Trialer Connectors
    A link to the trailer wiring you are asking about is provided, just scroll down the page to select the connector you have on your vehicle and trailer. The wires on the 5 pole flat are as follows White/ground, Brown/taillights, Yellow/left turn and stop, Green/right turn and stop and Blue/reverse lockout. The brown will run to both sides of the trailer and the yellow and green will only go to the respective side they are needed on. The Blue wire goes to the electric lockout solenoid for...
    view full answer...
  • Diagram for Utility and RV Style 7-Ways
    I attached a 7-way diagram picture that shows both ways normally seen how a 7-way is wired. The utility style which has the brown for taillights and the RV style that has the green for running lights. An RV would be wired like the center set of pictures.
    view full answer...
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  • What Size Wheel is Needed for Trailer Tire Size 165/65-8
    An 8 inch trailer wheel like the part # AM20016 that you referenced would be what you would need for the tire size 165/65-8 that you referenced.
    view full answer...
  • Adapting 4-Pole Flat on Toyota Sienna to 5-Pole Flat Using Part # 20036
    To provide the converter you already have with a 5-pole connector, you have two choices. You can use and adapter, like part # 20036. The blue wire on the adapter would tap into the circuit that feeds the reverse lights on your Sienna. A more permanent solution is available. You can cut off the 4-pole connector on the vehicle, and wire in a 5-way flat vehicle end, part # 20016. The brown, white, yellow and green wires would match those used by your existing connector. As with the adapter...
    view full answer...
  • How To Convert 4-Way to 5-Way Trailer Connector On 1995 Toyota Tacoma
    Yes, to install the 5-Flat Vehicle End, part # 20016, you will need to cut off your existing 4-way adapter. You will splice the wires from your 4-way to the 5-way which will match up color for color. Then, you will connect the Blue Wire to the reverse light circuit on your 1995 Toyota Tacoma. To connect to the reverse light circuit, you will need to find the wires that feed into the back of the tail lights. Then use a circuit tester, like part # 40376 to find the wire that has signal when...
    view full answer...
  • Troubleshooting Wiring On 2010 Ford Truck And Rewired Camping Trailer
    Wiring can be tricky so you will want to make sure you have all of the lights installed and properly grounded when wiring to prevent unpredictable results. First, you will want to make sure all of the functions on the harness at the back of your 2010 Ford truck are functioning correctly. You can do this by using a circuit tester like part # 40376. Enlist the help of someone who can sit in the cab and run through all of the functions to make sure they are all wired correctly. You can...
    view full answer...
  • How to Determine Wiring Functions on Vehicle and Trailer
    First, you would need to determine the function of each of the wires on the vehicle side of the connector by using a circuit tester like part # 40376. Typically, vehicle manufacturers use specific colored wires for certain functions, but you would have to test to make certain, as the color codes are not always reliable. You would then need to find out what function each of the wires on the trailer are. You could run a separate 12 volt battery to test the trailer lights. You would furnish...
    view full answer...
  • Parking Lights Do Not Work When Using a 7-Way to 4-Way Adapter with a 2008 Chevrolet 1500
    If you are seeing a TM on your trailer connector or on the 7-way to 4-way adapter, then the TM means tail/marker lights, or the parking lights, you are referring to. The first step that I would take is to get a circuit tester like part # 40376 and test each pin or blade on the connector on your 2008 Chevrolet 1500 to make sure it is functioning properly. If you have a signal for the tail lights at the connector on your vehicle, then you know the issue is not with the vehicle wiring. If...
    view full answer...
  • Testing Vehicle and Trailer Wiring to Install a 5-Way Flat Trailer Connector
    In order to determine the wiring functions you will need to test them with a circuit tester like # 40376 if needed. On the harness that you referenced, # 20016, white is ground, brown is running lights, yellow is left turn/brake lights, green is right turn/brake lights, and blue goes to the reverse light circuit. Many vehicles have separate turn signals and brake lights so on those vehicles a converter is needed. Converters can be vehicle specific so I would need to know the year, make,...
    view full answer...
  • Left Turn Signal Blinks on Trailer When Right Turn Signal is Activated on a 1997 Ford E-150
    I have attached a diagram of typical trailer wiring for you to check out as well as an article on trailer wiring that you may find helpful when troubleshooting this issue. Unfortunately, I do not have a wiring diagram for your 1997 Ford E-150 conversion van. It is important that you determine the function of each wire by testing them with a circuit tester like part # 40376 and not relying on the color of the wire. If the wiring on the trailer or vehicle wiring harness was modified at any...
    view full answer...
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  • Wiring 2005 VW to Tow Trailer with Amber Turn Signals Using 5-Way Connectors, Part # 20016 , 20017
    This is an unusual situation. Typically, trailers carry the brake and turn indicators on the same circuit, one for the passenger side, and one for the drivers side. The easiest way to wire this would be to cut off your existing 4- way connector and use a 5-way connector. Then wire the fifth lead on the vehicle side into the brake light circuit. You would need the 5-Flat Vehicle End, part # 20016, and the 5-Flat Trailer End, part # 20017. This would be the simplest way to wire your trailer.
    view full answer...
  • What is Needed to Apply Trailer Brakes with 2007 Toyota FJ Cruiser
    The blue wire for the trailer brakes of the trailer wiring needs to connect to a brake controller. A full 12 volt signal would lock up the trailer brakes so you need a controller which can put varying voltages on the brakes so that they apply is a smooth way consistent with you how you are applying the vehicle brakes. For a brake controller I would recommend the Prodigy P3 Brake Controller part # 90195. This is our best selling brake controller because of how well it works and how easy...
    view full answer...
  • Adapter Needed to Converter Motorcycle Trailer with 5-Way to 4-Way
    Yes, the converter you'd need is the part # 118158. This is designed to take combined circuits like you have on you motorcycle (referring to stop and turn being carried on same circuit) and separates them out so that you have a stoplight circuit on it's own wire. You'd want to install this on your trailer's wiring and you'd be set.
    view full answer...
  • Troubleshooting Trailer Wiring that Locks Up Trailer Brakes When Connected
    It sounds like the 12 volt accessory circuit and the brake output circuit are wired backwards and that is why the trailer brakes lock up whenever you connect the 7-way on your vehicle to your trailer. What I would recommend you do is use a circuit tester like part # PTW2993 to test for voltage on each of the pins as a buddy applies the various turn signal circuits and brakes and then compare that to the 7-way diagram I attached. If it all checks out then the problem is the trailer wiring...
    view full answer...
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