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Universal Wiring Harness for Hopkins Multi-Tow Vehicle-End Trailer Connectors - 4' Long

Universal Wiring Harness for Hopkins Multi-Tow Vehicle-End Trailer Connectors - 4' Long

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This 4' long universal harness can be hardwired into your tow vehicle's wiring system so that you can install Hopkins Multi-Tow connector 40965 or HM40975 (sold separately). Harness plugs directly into the Multi-Tow connector. 1-800-496-5010 to order Hopkins accessories and parts part number HM40985 or order online at Free expert support on all Hopkins products. Guaranteed Lowest Price and Fastest Shipping for Universal Wiring Harness for Hopkins Multi-Tow Vehicle-End Trailer Connectors - 4' Long. Accessories and Parts reviews from real customers.
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  • Reviews (28)
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Hopkins Accessories and Parts

  • Trailer Wiring
  • Vehicle Wiring Harness
  • 7 Blade
  • Hopkins
  • Universal

This 4' long universal harness can be hardwired into your tow vehicle's wiring system so that you can install Hopkins Multi-Tow connector 40965 or HM40975 (sold separately). Harness plugs directly into the Multi-Tow connector.


  • Lets you install a Hopkins Multi-Tow connector (sold separately) on any vehicle
  • Works with HM40940 (7-way), 40965 (6-way and 4-way) or HM40975 (7-way and 4-way)
  • Hardwires into your tow vehicle's wiring system
  • Plugs directly into your Multi-Tow connector


  • Wiring configuration:
    • Green: right turn signal
    • Yellow: left turn signal
    • White: ground
    • Brown: tail lights and side marker lights
    • Blue: electric brake
    • Red: auxiliary power
    • Purple: backup/reverse lights
  • Length: 4'
  • 90-Day limited warranty

40985 Universal Wiring Harness for Hopkins Multi-Tow Vehicle-End Trailer Connectors 40965 and HM40975 - 48" Long

Item # HM40985

Installation Details HM40985 Installation instructions

California residents: click here

Video of Universal Wiring Harness for Hopkins Multi-Tow Vehicle-End Trailer Connectors - 4' Long

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

Video Transcript for Trailer Wiring Harness Installation - 2002 Chevrolet Silverado

Speaker 1: Today the 2002 Chevrolet Silverado. We're going to review and install the universal wire harness, the Hopkins Multi-Tow vehicle and trailer connectors, part number HM40985.This is the connection point right here that goes behind your seven-fold connector. This is what's called the US car connector style. The cord has got a four-foot length to it and has provisions for all seven circuits. You've got ground, 12-volt power, brake controller output, left turn, right turn, run light circuit, and reverse lights. It also comes with a variety of butt connectors to suit different gauge of wires.

Up here larger wires. You're going to use the yellow ones. And for smaller wires, you're going to use the blue ones.These will work fine and do the function, but however for longevity, when I install this I'm actually going to replace these with some featuring butt connectors that are more suited for outdoor use. For larger diameter wires, I'm going to use part number DW05745-5. For my smaller wires, I'll use part number DW05744-5.

It also comes with a small vial of dielectric grease. I kind of like to put that around the connection right here to help protect the connection points from corrosion over the long term.A good reason to install this on your truck is a lot of times in older vehicles and trucks, if you run into situation where your wires are damaged . yeah, they had some minor repairs with some butt connectors and what not; however you can fix that just fine. But if something more worse happens such as the wire that goes into your connector, the US car connector, sometimes they just break right on the inside and you can't do nothing about it so you have to replace the whole assembly.Now, to remove this from our seven-fold connector, simply push down this tab right here. It may help to spray it down with some soapy water or even some lubricant to help pull apart, but push it in a little bit it helps.

Then this tab. You may also have a little gray locking tab. It just slide back out of the way to make it work, too. Push down on that center and pull it apart.We'll cut the wires to an even length one at a time. Take a moment and strip back the wires maybe about a little over a quarter inch maybe.

Wire stripped. You've got to get it to compress the wires by twisting them. Take a butt connector and a crimp tool. For our smaller wires, we're using a blue butt connectors. Make sure they're crimped. Give them a quick test. Now for our final three wires, we'll use our yellow butt connectors.Now, let's get our Hopkins part ready to go. I am going to remove this ring terminal here to hook that up to the factory ground wire, which is a white one on our truck. I'm just going to even these guys out and re-strip them.Onto connecting our wires, we're going to go white to white and pretty much match up color for color from here on out. Now, we've connected our wires color for color as you can see; however, there's a dark green and a light green. Dark green's going to be your turn signal, so that's going to go to your green on our Hopkins part. Now, there's a light green here. This is for reverse light. That's where color's going to change because purple on our Hopkins part. So we'll connect those two together just like we did before.We'll have an extra wire here for a third brake light which is commonly used on a camper shell. In our case there's no provision for it nor we need it, so we're just going to leave a butt connector for future use and we'll just leave it alone for now.Let's apply some heat to our heat shrink butt connectors. Always use a device like this to make your connections and shrink them up. If you can't do that with open flame. It's really easy with a lighter to over cook it and you'll get bubbles in your plastic here, and that's no good and it will cause it to deteriorate rather fast. We use some electrical tape, bundle them all together to make it nice and neat.We'll break out the dielectric grease here, just put it on the electrical connections right here. Just on the metal parts is all we need. Then we'll push this onto our factory connector. Align up the key way and then slowly but firmly push it in. You may or may not hear a click, and then give a tug back to make sure it's engaged.Zip ties will be needed because it does not come with our Hopkins part. We'll use it to bundle it up and keep it safe and out of the way. Then we'll cut off the tails.Now is the time to go ahead and try it out and test it. You at home will probably use a test light or just just your trailer to make sure everything works. I don't have a trailer handy so I'm going to use one of my testers from my shop. First off, we have a running light circuit, our left turn signal, our right turn signal. Let's check our brake signal, which we should have a constant output on the left and right turn. Okay. Now we'll try our brake controller, make sure to output there. And we'll also look for a reverse light circuit. Finally, we'll double check for our 12-volt power that goes out to our trailer for various accessories. And we've got battery power there.And with that, that will finish it for a universal wiring harness for Hopkins Multi-Tow vehicle and trailer connectors. Part number HM40985 on this 2002 Chevrolet Silverado.

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Customer Reviews

Universal Wiring Harness for Hopkins Multi-Tow Vehicle-End Trailer Connectors - 4' Long - HM40985

Average Customer Rating:  5.0 out of 5 stars   (28 Customer Reviews)

This 4' long universal harness can be hardwired into your tow vehicle's wiring system so that you can install Hopkins Multi-Tow connector 40965 or HM40975 (sold separately). Harness plugs directly into the Multi-Tow connector.


Works great, I've had it installed for about a year now. I bought to replace some trailer wiring that the previous owner had butchered. I installed with shrink wrap connectors and have not had any problems yet.


Perfect OEM Installation look for a vehicle that did not have tow package from factory. Easy to install


I was happy the way this connector fit. I separated the mounting bracket from the connector because this was going to replace a damaged oem connector. It was an exact fit, snapped in with no issues. I also ordered the hopkins #40985 harness to mate to it. A previous owner of my vehicle spliced into the oem harness to bypass the the original 7 blade connector. I felt it best to restore as much of the oem harness as possible. You will see some pigtails that the other person left when they cut things off and left a mess.
I can say the #40985 and 40975 harness and connector look very close to original. NOTE, I downloaded the color codes and wiring diagrams from ETRAILER, which was a big help. keep in mind that manufacturers do not often follow standard color code, I used a test light to verify function. All in all it was a successful outcome


I can't begin to say how pleased I am with the model 50002 backup camera system:
My 2003 Toyota Tacoma has a factory installed 4 wire system, however, I I needed the 7 wire connector to use with the backup camera. I emailed support and they quickly sent a reply with a link to instructions. It was an easy project - I had the wire conversion and the backup camera installed in less than 2 hours. I love the backup camera with the variable warnings as you approach obstacles and it works great for hooking up my trailer unassisted. 5 stars on both items - for sure!

Great! I love it, cant imagine being without it. The backup obstacle warning system is terrific - very accurate and lining up my trailer by myself couldnt be easier.
David H - 07/30/2017


Fit and function as stated.


Perfect fit with the HM40975 4pin/7pin connector. Wiring was correct - both position and color of wire. I didn't need the full 7-pins - I just cut the pigtail to length, clipped off the red, blue, and purple wires, and attached a 4pin connector to the other end.



Ok, I just found a package from you guys on my porch when I got home. I'd gotten an email today that said it'd been delivered, but I KNEW that was a mistake because I'd just ordered a couple days ago, paid ZERO for standard shipping, so was certain there was no way anything got here already. Get home, it's ALL there!!!!! It's all exactly what I ordered, and I'll be providing reviews of the stuff as I get it installed and used. But as for etrailer? Nothing but awesome!!!!!!!!! Amazing job. Now THAT'S customer service!


Very easy to install. Worked great with the trailer connector hm40975 I bought from you. Very good instructions


worked great!


Worked great!





Worked as it was designed for.


Too busy


Product fit perfect and arrived fast. Thanks


Excellent fit


Exactly what I was looking for.


As advertised, great product




great product.



Show More Reviews

See what our Experts say about this Hopkins Accessories and Parts

  • What Gauge are the Wires of the Universal Wiring Harness Hopkins # HM40985
    The ground wire (white), brake output (blue), and 12 volt accessory (red) are 12 gauge and the remaining wires are 14 gauge on the Universal Wiring Harness Hopkins # HM40985.
    view full answer...
  • Length of the Cable in the Universal Wiring Harness # HM40985
    The length of the cable included with the Universal Wiring Harness # HM40985 is 4 feet.
    view full answer...
  • Extension Harness for 7-Way after Installing Ranch Hand Rear Bumper
    The best solution we'd have is the part # HM40985 which you'd be able to cut off your old 7-way wiring harness and wire in place and have up to 4 feet of additional wiring.
    view full answer...
  • Will the Universal Wiring Harness Part # HM40985 Fit the Hopkins Endurance Multi-Tow Part # HM40950
    Yes, the Universal Wiring Harness part # HM40985 is compatible with the Hopkins Endurance Multi-Tow 7-Way RV and 4-Way Flat Trailer Connector part # HM40950. The male plug is referred to as a US car connector and is very common on most vehicles today. I have attached a wiring diagram for you as well.
    view full answer...
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  • Which Wiring Harness Will Work to Add a 4-Way and 7-Way Connector to 2009 Chevrolet Silverado
    Yes, the wiring harness # HM40985 will work with HM40920 on your 2009 Chevrolet Silverado. You will need the wire color code for both the harness and your truck: # HM40985 Green: right turn signal Yellow: left turn signal White: ground Brown: tail lights and side marker lights Blue: electric brake Red: auxiliary power Purple: backup/reverse lights Wiring color code on 2009 Chevrolet Silverado Dark Green - Right Turn/Brake Lights Yellow - Left Turn/Brake Lights Brown - Tail Lights White...
    view full answer...
  • Is Hopkins Universal Wiring Harness HM40985 a Fit for a 2005 GMC Sierra 2500
    The Universal Wiring Harness # HM40985 will fit your 2005 GMC Sierra 2500 Duramax and is compatible with any plug that uses the US Car Connector like the Hopkins # HM40975. When you install the Hopkins pigtail be sure that you connect the wires via function and not by color. You'll want to connect the following wires from the pigtail to the following functions on your Sierra: Green - right turn signal Yellow - left turn signal White - ground Brown - tail lights and side marker lights Blue...
    view full answer...
  • Replacement 7-Way Trailer Connector For a 2013 Toyota Tacoma With Factory Tow Package
    There are a couple different 7-way wiring harnesses that were installed on your 2013 Toyota Tacoma. Your 7-way may have a connector at the 7-way connection that will allow for you to quickly change it for a Hopkins Endurance Multi-Tow 7-Way # HM40950. You will need to check your 7-way for this connection point and also inspect the connector to determine if it is also damaged. If you do not have a connector at your 7-way or you have a damaged connector the Universal Wiring Harness # HM40985...
    view full answer...
  • 7-Way/4-Pole Trailer Connector For 2017 Ford F-350
    The Hopkins # HM40985 isn't a vehicle specific item it would hardwire into the tow package wiring on your F350 and if used with a 4-pole/7-way connector such as # HM40975, it would indeed power both trailer connectors. However, your 2017 Ford F350 should have a US Car connector located behind the bumper that would plug directly into a trailer connector like the # HM40975 for a super-easy installation.
    view full answer...
  • Does Hopkins 7-Way # HM40975 Fit 2017 Ford Explorer
    The Hopkins trailer wiring 7-way part # HM40975 that you referenced is a fit for your 2017 Ford Explorer and will attach directly to the wiring of the vehicle without any additional wiring. Basically it plugs right in to the round connector behind your rear bumper and you'd be set.
    view full answer...
  • Replacement Trailer Connector and Wiring Harness for a 2005 GMC Sierra 2500HD
    For your 2005 GMC Sierra 2500HD you are going to want to use the 7 and 4-Pole Trailer Connector Socket part # HM40975, not the Replacement Wiring Harness for Factory Wiring Harness part # 118282. The Tekonsha harness is for Nissan's and will not fit your Sierra. If you need to replace the wiring then you will also want to use the Universal Wiring Harness part # HM40985.
    view full answer...
  • Will Hopkins Backup Camera Work on a 25 Foot Motor Home
    You could potentially use the Hopkins backup camera # HM50002 on your 25 foot motor home. You will need to add the extension cable, # HM3100504061, given that your motor home is much longer than a typical passenger vehicle. If the motor home does not have a 7-Way trailer connector at the back then you will have to hardwire in the camera and you may need # HM40985 for the hardwire installation. I have linked a video showing a hardwire installation and a video showing a plug-in installation.
    view full answer...
  • How to Determine Wiring Functions on a 1997 Ford F-150
    In order to determine the wiring functions on your 1997 Ford F-150, you are going to have to use a circuit tester like # PTW2993 if needed. Have someone run through the various functions in the truck while you test with the circuit tester. The problem is that vehicle manufacturers can use any color wire they want for any purpose, and it changes from year to year and sometimes even within the same year (I have seen it). Because of this there is no standard and testing is the only way to...
    view full answer...
  • Installation of 4-Way Wiring Harness on 2019 Jeep Grand Cherokee to Upgrade to MOPAR 7-way/4-Way
    Since you don't have the tow package wiring on your 2019 Jeep Grand Cherokee, the Tekonsha T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # 118727 is needed. This harness will connect behind your vehicle tail lights and will connect directly to your vehicle battery to protect your electronics from overload. This will give you the 4-way trailer functions you mentioned. Then if you want to use the Mopar plug, you will simply cut the 4-way plug off the end and use the Hopkins...
    view full answer...
  • 4-Way Trailer Wiring Harness for 2021 Toyota Tacoma SR5
    We have 4-way wiring kits that fit your 2021 Toyota Tacoma and install easily but none of them would use the connectors you sent in a picture of. Instead the kits we have install by plugging inline with the taillight connectors like the part # C56349.
    view full answer...
    Image 1 for
  • Replacement 7- and 4-Way Trailer Connector Socket for 2011 Ford F-150
    The 7-way plug you are referring to on your 2011 Ford F-150 is the same thing as the 7- and 4-Pole Trailer Connector Socket w/ Mounting Bracket # HM40975. This will fit as an exact replacement for the factory 7-way on your truck. I have added a link to a video review and install of this connector for you to check out as well.
    view full answer...
  • Replacement Connector/Socket of 5th Wheel 7-Way Kit # 20111
    Sounds like you might be looking for the 7-way socket # HM40985 which plugs into the back of the 7-way. Or if you need the 7-way connector you'd want the # PK11893.
    view full answer...
  • Can Hopkins Universal Wiring Harness HM40985 Be Installed on Any Vehicle
    Yes, the Hopkins Universal Wiring Harness # HM40985 can be wired into any vehicle where you want to be able to install a matching 7-way trailer socket like # HM40940 or a combination 7-way/4-pole like # HM40975. Both of these vehicle-side connectors will accept the round U.S. Car connector plug that is on the harness # HM40985. This harness uses the following wire color configuration: Green: right turn signal Yellow: left turn signal White: ground Brown: taillights and side marker lights Blue:...
    view full answer...
  • Wiring Harness for 2003 Toyota Tacoma to Allow Installation of Hopkins Backup Camera HM50002
    The Hopkins Smart Hitch Backup Camera and Hitch Aligner System # HM50002 is designed for use with a 7-way-equipped vehicle since that type of connector provides the reverse light signal to activate it when you're backing up. Since your Tacoma has only a 4-pole flat trailer connector (which does NOT include a reverse light signal) you'll need to add one. The Hopkins system uses a round U.S. Car connector format for installation. You will need to install Hopkins Universal Wiring Harness...
    view full answer...
    Image 1 for
  • Parts Required To Add 7-Way And 4-Way Connector On 2002 Chevrolet Silverado 1500 W/ 4-Way Connector
    I would be happy to help you add a 4 way and 7 way connector combination to your 2002 Chevrolet Silverado 1500. The 2002 Chevrolet Silverado 1500 had either a connector to plug in a 7-way connector behind the rear bumper, or had blunt cut wires ready with all of the wiring to install a 7-way connector located along the frame rail or above the spare tire. The wires found are typically; Dark blue- brake controller output voltage Red or Orange- 12-volt accessory power Yellow- left turn/brake...
    view full answer...
  • How to Stop Trailer Wiring From Falling Out of the Factory Plug on a 2006 Chevrolet K3500
    You are correct, if the seal on the factory plug fails, the 7-Way trailer connector, # PK11916, will not be able to prevent water from entering the unit and consequently corrosion and short circuits are a side effect of this. I took a photo that shows this seal for you to view. At this time we do not carry a replacement seal for the factory connector. Nor do I know of anyplace that does, but you could use the Universal Multi-Tow® Harness, item # HM40985, to replace the factory plug, or...
    view full answer...
    Image 1 for
  • Recommended Trailer Wiring Harness for 2004 Toyota Tundra
    The Universal Wiring Harness for Hopkins Multi-Tow Vehicle-End Trailer Connectors - 4' Long # HM40985 will work but you would still need a converter because of how your truck is wired. I recommend using the Upgraded Modulite Vehicle Wiring Harness Kit w/ 4-Pole Trailer Connector and Installation Kit # 119147KIT and then the kit # ETBC7 to add the 12v power, brake controller output, and reverse light functions.
    view full answer...
  • Availability of Extension To Relocate 7-way Trailer Connector
    We don't offer a dedicated extension, but I have a couple of alternatives that can be used to do that for you. The least expensive option would be to use a 4-foot pigtail like # HM40985, but you'd need to cut off the factory round US CAR connector that's currently plugged into the rear of your 7-way and wire in the pigtail. The wire color function is shown on the linked product page. I'd recommend using heat shrink butt connectors like # DW05745-5 to protect the connections from moisture. An...
    view full answer...
  • Availability of U.S. Car Connector to Pigtail Wiring Harness and Compatible 7-Way
    Both the Hopkins Universal Wiring Harness # HM40985 and the Pollak Replacement Harness # PK11998 are 4-feet in length and provide a round U.S. Car type connector on one end and pigtail leads on the other. They are indeed interchangeable. I pulled one each of the two 7-way parts you referenced, parts # HM40940 and # PK11893, and measured their center-to-center mounting hole spacing. Part # HM40940 has 4 holes spaced 1-1/2-inches top to bottom and 2-1/4-inches side to side. Part # PK11893...
    view full answer...
  • Installing a 7-Way Trailer Connector and Brake Controller on 2016 Toyota Tacoma without Tow Package
    You can use trailer connector # HM40975 with wiring harness # HM40985 but it will require some hardwiring to install it in your 2016 Toyota Tacoma. The first thing you will need to do is install a 4-Way connector on the truck. This is because the truck has turn signals that are on a separate bulb from the brake lights. A converter is needed to combine the signals which is what a trailer uses. To add a 4-Way and converter I recommend # 119178KIT because it has proven to be reliable. I...
    view full answer...

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