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Hopkins Wiring Harness with 5-Pole Flat Trailer Connector - Vehicle End - 5' Long

Hopkins Wiring Harness with 5-Pole Flat Trailer Connector - Vehicle End - 5' Long

Item # HM37908
Our Price: $15.13
Trailer Wiring
Shipping Weight: 0.31 lbs
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Wire your vehicle to tow a trailer with this universal, splice-in wiring harness. Provides reverse function to release surge brakes. Corrosion-resistant terminals are long-lasting. Great Prices for the best trailer wiring from Hopkins. Hopkins Wiring Harness with 5-Pole Flat Trailer Connector - Vehicle End - 5' Long part number HM37908 can be ordered online at or call 1-800-940-8924 for expert service.
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  • Reviews (12)
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  • Videos (2)
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Hopkins Trailer Wiring - HM37908

  • Trailer Connectors
  • Vehicle End Connector
  • 5 Flat
  • Plug and Lead
  • 0 - 5 Feet Long
  • Hopkins

Wire your vehicle to tow a trailer with this universal, splice-in wiring harness. Provides reverse function to release surge brakes. Corrosion-resistant terminals are long-lasting.


  • 5-Way flat trailer connector at the back of your vehicle plugs into the connector from your trailer to power your trailer's signal lights
    • Includes reverse function to release brakes when backing up
    • Ideal for use with marine-type trailers equipped with surge brakes
  • Simple installation
    • Hardwire to existing trailer wiring
  • Corrosion-resistant terminals are long-lasting


  • Harness length: 5'
  • Wiring configuration:
    • White: ground wire
    • Yellow: left turn/brake light
    • Green: right turn/brake light
    • Brown: tail lights
    • Blue: reverse lights
  • 90-Day limited warranty

37908 Hopkins 5-Way Flat Connector - Vehicle End - 60"

Video of Hopkins Wiring Harness with 5-Pole Flat Trailer Connector - Vehicle End - 5' Long

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

Video Transcript for Hopkins Wiring Harness Review

Hey, everybody. Ryan here at etrailer. Today, we're gonna be checking out the Hopkins 5-way flat trailer connector for your vehicle side. For those of you that are unfamiliar with a five-way flat, this is essentially identical to kind of your classic four-way flat type connector. I'm sure a lot of people have seen them. They're just on about a ton of different medium size, smaller size trailers.

But this being the five-way though, you get one extra signal and that will be your reverse light signal. So, we have our ground wire, our taillight signal, our left turn as well as stop, right turn and stop, and this blue one is our reverse light. Now, there's a couple of different reasons you would wanna use this. I'd say probably the most common is for when you're towing a boat that has surge brakes on it. That way, when you're going to launch the boat or just even back it up into the garage or whatever, it'll have this reverse light signal and it won't lock the brakes up.

That way, you can actually back it up and not, you know, drag it across the ground. But you can kind of get creative too. I know there's some people that use this signal. They might have some small LED lights like as back up lights on their utility trailer and you can get a signal from this. That way, when you put it in reverse, it sends power out to whatever you have it wired up to.

So, you can kind of get creative on what you can do with this. Now, keep in mind this isn't gonna have a ton of amperage. So, you can't run a hundred lights off of it. But you got one or two lights on it, especially if they're LEDs, chances are good it's gonna power them right up and everything else. So, you know it's one of those deals that, in a sense, it's almost an upgrade over kind of your factory four-way or your regular four-way type connector.

And that kind of brings me to my next point. You are still able to use a four-way connector with this. So, let's say, if you have a boat trailer with the five-way and you also have the utility trailer with the standard four-way, you're still gonna be able to use the same connector. You won't need an adapter or anything. So, just for example, this is a trailer side, kind of your standard four-way and it'll still plug in. It'll still get its regular signals and everything else. So, like I said, you're not gonna need an adapter or anything like that. But I do want to mention, for this to work, you are going to need existing four-way wiring because this is essentially just a pigtail, right So, it's the connector and those five wires that come off of it. So, you are gonna have to kind of splice this into your existing wiring. And then, of course, you're gonna need to be able to find a way to pick up your reverse light circuit too. Whether it be your reverse light bulb, maybe your reverse light fuse in the dash or whatever, you're gonna need that power source, right So, that's just something to keep in mind whenever you're thinking about hooking this up to your vehicle. This particular harness is going to be five foot in length. So, changes are pretty good you're not gonna need all that wiring but it is good to have, right That way, if you do have to stretch it a little bit further, you got it, which kind of brings me to my next point. When installing this, it's probably a good idea, I would suggest picking up five heat shrink-type butt connectors, especially if you're gonna be keeping this outside since you have to splice in your existing four-way wiring. And it's gonna be pretty much the same for all vehicles. You splice in that four-way and then obviously, pick up your reverse light circuit, which like I mentioned earlier, you usually get it from your reverse lights, or one of your fuses, things like that. So, every vehicle is gonna be a little bit different but the idea is the same. I do wanna mention too, this isn't gonna come with a dust cover. You know how sometimes there's a little cap that'll plug over this So, that is something that you can grab separate and excuse me, you can also get, there's all different types of brackets and things of that nature where you can mount this up on your hitch. And this is even a good example. So today, I just put some of this black wire loom over our wires just to help kind of, kind of help it blend in a little bit better. So, you can use something like this as well if that's the style you're going for or the look you're going for. But other than that, at the end of the day, it's gonna be a good way to be able to use different types of accessories or pull those different types of trailers around that you otherwise wouldn't be able to. So hopefully, this kind of cleared up a few things and answered some of your questions on what this is, and what it actually does, and gets you going in the right direction. And that'll finish up our look at of the Hopkins five-way flat trailer connector for the vehicle side..

Customer Satisfaction Score:

Customer Reviews

Hopkins Wiring Harness with 5-Pole Flat Trailer Connector - Vehicle End - 5' Long - HM37908

Average Customer Rating:  4.8 out of 5 stars   (12 Customer Reviews)

Wire your vehicle to tow a trailer with this universal, splice-in wiring harness. Provides reverse function to release surge brakes. Corrosion-resistant terminals are long-lasting.


The Glolight LED trailer set is the perfect replacement for my tow dolly. It is light weight and much more visible than the standard bulb lamp set the trailer was equipped with. Installation was quick and very easy, I will recommend this to all needing to change theirs out...


Great Prices and Fast Shipping


Thank you for shipping it out fast. Plan to use it for my motorcycle.


Good product. Would be even better if wire was tinned copper


The product was good, but it took 45 days to get it.


Just what I wanted. No frills straightforward ready to install. Good value and quality.


Great product. Just what I needed.


Haven't used it yet but pretty straight forward.






See what our Experts say about this Hopkins Trailer Wiring

  • Subaru with 5-Way Flat Trailer Connector to Trailer with 4-way
    If your Subaru already has a 5-pole flat trailer connector like the Hopkins # HM37908, you will not need any additional parts to be able to connect with the 4-way flat on your trailer. You will just simply connect the two harnesses, and the additional pin on the Subaru's 5-way will just not be used.
    view full answer...
  • Towing a Trailer with a 4-Way Trailer Connector with a Vehicle that has a 5-Way Connector
    It sounds like you're trying to tow a trailer that has a 4-way connector, like part # HM38168, with a vehicle that has a 5-way connector, like part # HM37908. If this is the case you don't need any additional parts or a converter. A 4-way and 5-way will plug into each other you just won't have the 5th pin connected. Nor will you have the function that's carried on that pin. If this isn't what you're trying to do then let me know your exact set up so I can be more help.
    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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  • Solution to Activate Reverse Lockout Solenoid of Surge Brake Trailer Being Towed with Front Hitch
    This is a really good question. Probably the best solution would be to wire a 5-way to the front of your truck like with the part # HM37908. Run the blue wire to your positive battery post and then the white to the ground and whenever it's plugged into your trailer the reverse lock out solenoid will activate and allow the trailer to move.
    view full answer...
  • Wiring 2005 VW to Tow Trailer with Amber Turn Signals Using 5-Way Connectors, Part # HM37908, 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 # HM37908, and the 5-Flat Trailer End, part # 20017. This would be the simplest way to wire your trailer.
    view full answer...
  • 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...
  • 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...
  • 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...
  • 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...
  • 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...
  • 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 # HM37908. The brown, white, yellow and green wires would match those used by your existing connector. As with the adapter...
    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...
  • 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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  • 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...
  • Connecting 4-Way on Motorcycle to 5-Way on Trailer
    I think what might be going on here is that your trailer uses separate wiring (which is what a motorcycle would typically use as well) but your motorcycle has combined wiring, or at least is equipped with a converter to combine it before the connector, which is why it's equipped with a 4-Way instead of a 5-Way. With a combined wiring setup the turn and brake signals on each side of the motorcycle are sent along the same circuit. This is why the lights aren't working correctly on the trailer...
    view full answer...
  • Parts Needed to Convert a Separate Tail Light Signal of a Honda Goldwing to Combined for Towing
    It sounds like the adapter you used dropped the brake light circuit when it went from a 5-way to a 4-way. Normally on a 4-way the brake light circuit is on the turn signal circuit. Motorcycles usually have a separate wire/circuit for just the brake lights separate from the turn signals so I believe that is where your problem is from. I believe I have a solution for you, but not with using the adapter you have. I would recommend you cut off the 5-way on your motorcycle. Wire in a tail...
    view full answer...
  • Replacing 4-Way Female to 5-Way Male Wiring Loop
    I do have a solution for you, however the female 4-Way to male 5-Way loop that you have is no longer available. Instead of using another adapter like this one your best option will be to actually cut off the 4-Way connector from the trailer and splice in a 5-Way like the Hopkins # HM47913 in its place. The blue wire from the 5-Way will go to the blue wire that you mentioned coming from the actuator. With this in place on the trailer you will be able to connect directly to the 5-Way on the...
    view full answer...
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  • 2012 Honda Goldwing Motorcycle 5-Way Trailer Wiring Recommendation
    The 5-way harness on your 2012 Honda Goldwing is a wiring setup that has separate turn signals from the stop lights. What that means is there is a separate brake light bulb from the turn signal bulb on either side of the trailer. The fifth wire on your bike's trailer connector is not a reverse light circuit so it will be needed. Typical trailer wiring has the stop and turn signals combined so only 4 circuits are needed. You can wire up your trailer the same way and everything would be...
    view full answer...
  • Wiring Trailer Lights for 2009 Pontiac Vibe Without Using Converter
    Probably the easiest way to handle this situation would be to use a 5-way connector, part # 20017 for the trailer and part # HM37908 for the vehicle end. Use the extra wire for the brake light lead. If the trailer needs to be towed by another vehicle, simply use the 4 to 5 Way Adapter, part # 47515.
    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...
  • Converting a 4-Pole Wiring Harness to 5-Pole on a 2004 VW Touareg for Towing a Boat Trailer
    Since you have the # 118509, custom wiring installed on your Touareg, you have two options. You can use the 4 Pole to 5 Pole Trailer Wiring Adapter, item # 47515, or you can cut the 4-Pole connector off of the harness and splice in a 5-Way connector, item # HM37908. In either case the blue wire will be routed to the vehicle reverse light circuit, behind one of the vehicle tail lights, and spliced in there. Then, when the vehicle is in reverse, the electric lockout on your surge coupler...
    view full answer...
  • Will a Trailer 4-Way Plug Into a Vehicle 5-Way Without Adapter
    Yes, you can plug a trailer side 4-way trailer connector part # 002402 into a vehicle side 5-way connector part # HM37908 without any adapters needed.
    view full answer...

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Info for this part was:

Employee Lindsey S
Edited by:
Lindsey S
Employee Michael H
Expert Research:
Michael H
Employee Jameson C
Expert Research:
Jameson C
Employee Joshua S
Video by:
Joshua S
Employee Jacob T
Video Edited:
Jacob T
Employee Cole B
Installed by:
Cole B
Employee Ryan G
Installed by:
Ryan G
Employee Alexander C
Written by:
Alexander C

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