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Hopkins Wiring Harness with 4-Pole Flat Trailer Connector - 48" Wire Lead

Hopkins Wiring Harness with 4-Pole Flat Trailer Connector - 48" Wire Lead

Item # HM48035
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Wire your vehicle to tow a trailer with this universal, splice-in wiring kit. Includes 4-way flat connector and 48" of bonded wire. Designed for use with 2-wire electrical systems. Lowest Prices for the best trailer wiring from Hopkins. Hopkins Wiring Harness with 4-Pole Flat Trailer Connector - 48" Wire Lead part number HM48035 can be ordered online at or call 1-800-940-8924 for expert service.
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Hopkins Trailer Wiring - HM48035

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

Wire your vehicle to tow a trailer with this universal, splice-in wiring kit. Includes 4-way flat connector and 48" of bonded wire. Designed for use with 2-wire electrical systems.


  • 4-Way flat trailer connector at the back of your vehicle powers your trailer's signal lights
    • Compatible with 5-pole, 6-pole and 7-pole adapters (sold separately)
  • Rubber-molded connector and bonded wire provide maximum durability
  • Simple installation
    • Hardwires to existing wiring
  • Corrosion-resistant terminals ensure durability


  • Application: vehicles with 2-wire lighting systems
  • Wire gauges:
    • White: 16
    • Green: 18
    • Yellow: 18
    • Brown: 18
  • Lead length: 48"

48035 Hopkins 4-Wire Flat Car End Connector - 48" Long

Installation Details HM48035 Installation instructions

California residents: click here

Video of Hopkins Wiring Harness with 4-Pole Flat Trailer Connector - 48" Wire Lead

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

Video Transcript for Trailer Wiring Harness Installation - 2006 Ford Van

Today, on our 2006 Ford van, we'll be installing the Hopkins wiring harness, with four pole flat trailer connector. Part number HM48035. Now, our van is equipped with factory wiring, where you could plug in a plug that has a four pole on it, but it's only available through Ford. Instead of doing that, we're going to go ahead, cut the end of that connector off, and hard wire our four pole flat trailer connector. Since we're going into the factory wiring harness, it will be protected by the factory fuses. Not that you're underneath our van, we'll go just in front of our spare tire, up here on the frame rail. You see there will be four wires here and a plug that's just going in to a holder here on the frame. Pull and unplug that, and that'll be our four pole wiring.

You see that round connector, this is the factory plug. We're just going to go ahead and cut that off, and then splice into the wires. It will be color for color. Brown will be the running light circuit. The yellow will be the driver's side turn signal. The green will be the passenger side turn signal.

We're going to go ahead and ground our wire, right here, to our frame. There's already a ground here, so we'll just use that one. Go ahead and snip off the factory connector. Now we have access to our wires. It is always a good idea to go ahead and check these with a tester before hand, to make sure your factory wiring harness is working on your vehicle. Now, we'll go ahead and take our new wiring harness.

We're going to go ahead and peel back the wires from one another. Just peel it back a little bit. That'll just make it a lot easier to go ahead and strip them and add our butt connectors on. Now, these are all stripped back, I'm going to go ahead and crimp on some heat shrink butt connectors. Now that we have our butt connectors here on our new wiring harness, we'll go ahead and strip back the wires that are attached to the vehicle. Now go ahead and wire our new wiring harness into our factory wire.

Start here with the yellow wire, which will be our driver's side turn signal and brake signal, fit into our butt connector. Make sure it's crimped nice and good. Follow that up with the green wire. Next, we'll continue with our brown wire, then the black wire will go to the white wire. That'll be the ground for the circuit. Now that they're all crimped, we can go ahead and take our heat gun, and we'll go ahead and shrink the butt connectors, seal them up, then we'll wrap them up with electrical tape, just to give them another layer of protection. As you can see, we ran our four pole here to our hitch, so we have easy access to it when we go to hook up our trailers. Then we just zip tied it in a couple of spots, just to secure the wire. Trim the excess off the zip ties, and we can go ahead and test our new wiring. Go ahead and take our test light. Ground it here to the open stud on our four pole. Turn the running lights on, test the brown wire. Let's go ahead and cancel the signal light. Then we'll go ahead and turn our driver's side, or left turn signal on. Go ahead and turn the passenger side turn signal on. Then, we'll hit the brakes and we'll have a constant signal from the green and the yellow wire. Just like that, we're ready to hook up and hit the road. That'll do it for the install of the Hopkins wiring harness with four pole flat trailer connector. Part number HM48035, on our 2006 Ford van. .

Customer Reviews

Hopkins Wiring Harness with 4-Pole Flat Trailer Connector - 48" Wire Lead - HM48035

Average Customer Rating:  5.0 out of 5 stars   (39 Customer Reviews)

Wire your vehicle to tow a trailer with this universal, splice-in wiring kit. Includes 4-way flat connector and 48" of bonded wire. Designed for use with 2-wire electrical systems.


Super simple to install and it followed the installation video exactly.


SMI Stay in Play Duo installation in 2015 Jeep Wrangler Unlimited –
Packaging was great with everything needed included plus extra items for various installation methods of you’re choosing. Upon initial investigation and survey, everything except the CD Information pack was accounted for.
No big deal, as I had previously watched 2 different Youtube installations found on the internet. In fact, the internet videos were what I used as my step by step installation process, and the written instructions were only used for concerns where the video may not have been as clear as I had hoped for.
Understanding that everyone has their own style and methods for doing this project, I purposely was not in a hurry to rush through it. All in all, I took @ 8 hours to install the Adapter 4 to 6 pole #30637, the EZMount Tow lights Kit, and the Stay in Play Duo Braking System.
I choose the EZMount because I didn’t want to mess around with the OEM taillights and wiring. Magnetic lights don’t work so well on composite tops and I didn’t want to stick them to the sides of te Jeep, so I modified the EZ mount to wrap around the thickness of the rear glass hatch on both sides. I added a 2”x 4” pc of Velcro on the inside of the glass hatch and the mating surface of the plastic light housing - to hold the lamps in place until the rear gate was closed.
I ran the wire harness on the inside under the trim all the way up to the front and through the grommet in the firewall. The flat 4 wire was routed and secured up to the Adapter 4 pole to 6 pole that I had fastened to the Blue Ox base plate.
The actual installation of the SMI unit and assorted parts went rather smoothly. Most difficult issue was the lack of working space in front of the driver’s seat area. Installing the screw that holds the G force controller on the front (the side towards the front of the car) was difficult as it was almost a blind installation due to lack of room. The nut and fender washer used through the fire wall for attaching the air cylinder cable bracket was a challenge to reach - tight fit with not much room for one's hand and arm.
Other than that, no big surprises – just a lot of tedious steps to do when you want to be sure that it is being installed properly – take your time and don’t be in a hurry.
Once everything was installed – it all worked when I checked the system out. The only thing that may seem a bit odd is that when setting the G force initially, the compressor will shut off while adjusting per instructions. To do this initial adjustment, the wife stepped on the brake in the Motorhome, with the switch “On”. The compressor starts, and the brake is pushed down by the Air Cylinder, at which time I slowly adjusted the G force until the compressor shuts off. I secured the adjusting bolt and I told the wife to take her foot off the brake and then re-apply them. The compressor did not start again and the air cylinder did not apply the brakes in the Jeep. After setting the G force per instructions, the unit didn't turn on when the brakes in the Motorhome were applied - but since we were not moving - all I can assume is that the brake system will function while slowing down once the accelerometer setting (the sensitivity setting on the G force box) has been met. I assume that the sensitivity setting method includes a way to ensure the Jeep brakes are not engaged too frequently and only until needed.
This is the only step that is a tad bit confusing without an explanation as to what to expect once the G force sensitivity is set.
Lastly, I checked the brake away switch and it turned the compressor on and applied the brakes as expected.
Overall - the installation went rather smoothly. Can't wait to see how the product works once we hit the road. I'll check back and provide an update later.


Not much to say but it works


The product will be replacing an existing pigtail that is showing signs of corrosion on the terminal ends and sometimes need a light wire brushing to make electrical contact. The terminals on this piece appear to be a better metal and time will tell if they resist the corrosion any better.


Glad they carry Hopkins products. I prefer Hopkins over others because the wiring plastic insulation is heavier. Excellent quality product.


Ordered this Hitch for a 1998 Ford F-150. It was ordered late Thursday night, and was setting on my front porch Monday morning. This is some of the fastest service I have experienced for a large item. My compliments to your shipping department.
The F-150 has a 17 inch spare so no need to drop it. the hitch went right up. Two men lying under the truck had it mounted, and torqued down in less than 30 minutes. Beautiful hitch, and really well made, and since I have built several Class IV hitches from scratch I know what I'm talking about.


I bought wiring and connectors to rewire a 30+ year old utility trailer. All items purchased were of excellent quality and the trailer lights work well. I was especially pleased with the jacketed 4 conductor wiring.


I am very happy with Rebecca's help over the phone and assisting me with ordering my wiring harness with bracket on my 2015 Chevrolet Colorado. I received exactly what I need. Would recommend Etrailer to anyone. Thanks Rebecca and Etrailer


The customer service at etrailer is, as always, excellent. My product shipped quickly and arrived soon after I ordered. The videos and instructional material were very helpful in ensuring I was purchasing the correct product. For trailer or trailer related products I will not shop anywhere else. I needed this because my old harness had corroded terminals. This will be simple to replace.


Works fine

works just right
Bob D - 07/16/2021


I haven’t installed the wiring yet, but if I have a problem it won’t be because of etrailer since they didn’t make the wiring harness. Will do this tomorrow.


Wire harness seems to be well made. Fits my trailer plug perfectly. Great price from etrailer, and pretty quick shipping as well. This is my second purchase from etrailer and I couldn't be more pleased with both transactions.


wiring harness of good quality, just as shown, thanks


An amazing wealth of products.
And an
even greater knowledge base to draw on for info and direction. is my favorite "bookmark"


worked out great


Product was received promptly and worked great on an older Jayco popup camper. I would use etrailer on future purchases for any of my trailer needs!


Great stuff to work with. Pallet racks and etrailer parts


I've always gotten good quality products and if there was a Problem Prompt an Courteous Responses,,Thx for always being Professional,,,


As expected.


Quick and easy to connect


great prices and prompt shipping


Works great so far.



As expected.


Show More Reviews

Ask the Experts about this Hopkins Trailer Wiring

  • Installing 4-Way Trailer Connector on 2000 Dodge Grand Caravan
    Your 2000 Dodge Grand Caravan uses a separate wiring system, meaning that the brake and turn signals are sent along separate wires. Because of this, a converter is required and you will not be able to use the Hopkins Wiring Harness with 4-Pole Flat Trailer Connector # HM48035 referenced in your question. To install a 4-way connector on your Grand Caravan, I recommend using the Tekonsha T-One Vehicle Wiring Harness # 118334. This includes the needed converter and the T-One connector will...
    view full answer...
  • Towing Trailers with 4-Way Connectors Using a Vehicle With a 5-Way Connector
    Actually, you don't have to change anything. The 4-way connectors on your trailers fits into the 5-way on the vehicle except you'll have an extra pin not being used. Since it's the trailers that are missing a pin that means you don't need that function, which is likely a reverse light circuit. If you want you can replace the connectors on both trailers with a 5-way like part # HM47910 but you still won't use the function of the fifth pin. The other option is to replace the 5-way on...
    view full answer...
  • Recommendation For A Wiring Harness That Is 60 Inches Long
    Yes, I have what you are looking for! The Curt Vehicle Wiring Harness with 4-Pole Flat Connector, Item # C58044, is very similar to the Hopkins Wiring Harness, Item # HM48035, that you referenced. It is a universal wiring harness kit with all the necessary hardware needed for installation that is 60 inches long. I have attached a video for you to check out.
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  • How To Install A Wiring Harness For Towing On A 1972 Volkswagen Bus Campmobile
    I do have a trailer wiring harness option for you to consider however, there are no t-connector wiring harnesses for your 1972 Volkswagen Bus Campmobile. In order to install a wiring harness on your vehicle for towing, you will need to hardwire in a harness such as the Hopkins Wiring Harness with 4-Pole Flat Trailer Connector part # HM48035. The white wire will need to be grounded to the chassis, the brown wire will be spliced into the vehicle's tail lights, the yellow wire will need...
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  • Trailer Wiring Harness for a 2005 Ford Escape
    Your 2005 Ford Escape has what is called a separate or 3-wire system. This means that it has turn signals and brake lights that are on different circuits. Trailers have what is called a combined or 2-wire system which means the brake lights and turn signals are on the same circuit. In order to have the proper functions from a vehicle side 4-Way you will need a wiring harness that has a converter. The converter takes the separate signals from the vehicle and combines them so that the 4-Way...
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  • Will the 7-Way Round Pin to 4-Flat Adapter Work On a Semi
    I do have an option for you but the 7-Way Round Pin to 4-Flat Adapter part # 118709 won't work on semi's as there is no converter integrated into the adapter. The lights on a semi are separate and the lights on a trailer are combined so a converter is required. Therefore, you will have to make your own adapter using the Hopkins Tail Light Converter part # HM48847, 7-Round Connector part # PK11700, and Hopkins Wiring Harness with 4-Pole Flat Trailer Connector part # HM48035.
    view full answer...
  • Availability of a Replacement 4-Way Vehicle Side Plug End
    I have a solution for you. The Hopkins Wiring Harness, # HM48035, will replace the malfunctioning 4-flat plug on your vehicle. You will just need to cut off the current plug and using Deka Heat Shrink Butt Connectors, # DW05744-5, connect the new plug to your wiring harness.
    view full answer...
  • Connecting Motorcycle with 6-Way Flat to Trailer with 4-Way Connector
    Motorcycle trailer wiring typically has separate circuits for the stop lights and turn signals while trailer wiring will have these circuits combined. You can verify this by testing the pins on the 6-Way with a circuit tester like # 40376 while somebody runs through the lighting functions. If this is the case then you will need to use a converter # RM-732 on the motorcycle wiring to convert the lighting functions before the connector. A 6-Way flat is not a standard connector and there...
    view full answer...
  • Converting Wiring On 1998 Ford Ranger From 4-way To 7-Way For Trailer
    We have what you need to convert your wiring from 4-way to 7-way to match your trailer. You can cut the round connector off on the vehicle side and replace it with part # HM48035. Then you need to use part # ETBC7. Your 4-way flat will plug into the # ETBC7 and you will need to run the additional wires. You will need to attach the white wire from the # ETBC7 to a clean bare metal surface for a ground. The blue wire will go to your brake controller. The purple wire is used for reverse...
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    Image 1 for
  • Adapter Needed for External Battery to Trailer Side 4-Way
    We do not have a direct adapter, but you could very make your own. Using alligator clips and the Hopkins Wiring Harness # HM48035 would allow you to do this. I do recommend installing at least a 15 amp fuse # C58450-1 and Fuse Holder # SWC9538 between the 4-Way and the battery to keep your setup safe in case of a short.
    view full answer...
  • Can 2019 Jeep Wrangler Use Hardwired 4-Flat Wiring Harness
    Yes, you can use the Hopkins Wiring Harness with 4-Pole Flat Trailer Connector # HM48035 on your 2019 Jeep Wrangler if you want to hardwire a 4-flat, though I do recommend the T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # 118786 which fits your '19 Jeep and includes a power module connected to your battery. This is important because you won't overload your electrical system with this harness, something that will protect your Jeep in a way the Hopkins harness cannot....
    view full answer...
  • How To Make a Trailer Wiring Harness Adapter with Two Vehicle Side Trailer Connectors
    In order to obtain a trailer wiring harness with two vehicle side trailer connectors you will need to either splice two of the Hopkins Wiring Harness with 4-Pole Flat Trailer Connector part # HM48035 into one another with the Deka Heat Shrink Butt Connector part # DW05744-5 or you could just install the Hopkins Endurance Quick-Fix Replacement 4-Way Flat Trailer Connector part # HM48190 onto the opposite end. Unfortunately, we do not have a complete trailer wiring harness like the Roadmaster...
    view full answer...
  • Troubleshooting Wiring on Boat Trailer With 1998 Ford F-150
    Before getting a new connector I recommend testing to see if the issue is the wiring. You'll need to use a circuit tester such as # 40376 to test the 4-way on your 1998 Ford F-150. Check the wiring going into your harness from your tail lights to see if those are correct, if not then the issue is with the vehicle wiring. If the signals going to your harness are okay, you'll need to test the signals coming out of the harness, and if they are correct then your issue is likely going to be...
    view full answer...
    Image 1 for
  • Replacement 4 Flat Connector for a 2013 Ford Explorer
    We definitely have replacement options for a 4 Flat on your 2013 Ford Explorer. I am including a full replacement for your T harness, as this is what I suggest doing, but also an option to cut off the end of your 4 Flat and splice on a new end. The Tekonsha T-One Vehicle Wiring Harness with 4-Pole Flat # 118540 will be a full replacement for your damaged harness. This is a plug and play harness that will take at most 10 minutes to get installed. Due to all this, I recommend going this...
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  • 4-way Round Trailer Connector to 4-way Flat Connector
    I have a solution for you. However, we do not have an adapter to fit your 4-pin round connector on your trailer. Because of the rarity a 4-way round connector, I recommend either cutting off the 4-way round and attaching a 4-way flat, or splicing a 4-way flat into your wiring in addition to the 4-way round. To attach a 4-way flat, you can use part # HM48035. If you remove your 4-way Round connector, you will want to use butt connectors # DW05744-5. If you want to add the 4-way Flat...
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  • Installing Additional Brake Light to Mount on Kayak that Overhangs Trailer
    First, to replace the 4-way connection on your trailer with a 7-way, you can use the Pollak Black 7-Pole, RV-Style Trailer Connector - Trailer End # PK12706. You will just cut the wires on the existing 4-way and splice them into this connector. Then to add the connections needed on your trailer to use the Optronics Thinline LED Trailer Tail Light # STL59RB as a portable option for use at night, you can use a vehicle end 4-Pole Flat connector like the Hopkins # HM48035 that will come off...
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  • How to Add 7 Way to 1998 Chevy Truck with 5 Way Plug
    I have a solution for you to add a 7 way connector to your 1998 Chevy truck. You would first need to cut the 5 way plug off and wire in a 4 way using the Hopkins Wiring Harness with 4-Pole Flat Trailer Connector - 48" Wire Lead # HM48035 and some butt connectors # DW05745-5; you'll want to leave the reverse light wire loose, since that will connect to the 7 way on its own. To add the 7 way you can use the # ETBC7, which will accept the 4 way plug you've just installed, and make connections...
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  • How to Install Wiring Harness 118496 in 1995 Toyota T100
    The installation of a 4-flat connector such as the T-One Vehicle Wiring Harness # 118496 in your 1995 Toyota T100 is a very simple and straightforward process; it only requires plugging in the T-connectors at the taillight wiring harness. I was unable to locate what harness you ordered from us so I'm not certain what exact harness you used but the process should not be any different (see linked installation video which shows how this harness installs). If you only cut off the connector...
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  • Trailer Wiring Adapters Available for 7-Pin Flat to 4-Pin Round Connectors
    I have some wiring adapter options for you, but if your vehicle has a 4-Pin round connector, like # PK11404, we only offer adapters to connect to 4-Way flat trailer connectors and tow bar wiring extensions like # HM47043 that you referenced. If you're looking for a wiring adapter to allow you to connect a trailer with a 4-Way flat connector, like # 18004, to your vehicle's end 7-Way blade-style socket, like # PK11893 we have an adapter that will work great. For this set-up, you can use...
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  • Recommended License Plate Brackets For Hitch Mounted Cargo Carrier
    We do have license plate brackets that can be mounted on a carrier. If you are looking for a bracket with an LED light I recommend part # LPL55CB. For a lighted bracket with a replaceable incandescent bulb I recommend part # LP55CB. To install either of these lights the black wire would need to tap into the running light circuit of your vehicle and the white wire would need to get grounded. The best way to wire this is to use a harness like part # HM48035. If you don't want to install...
    view full answer...

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