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7-Way Molded Trailer Wire Connector - 3' Long

7-Way Molded Trailer Wire Connector - 3' Long

Item # H20042
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Lowest Prices for the best trailer wiring from Hopkins. 7-Way Molded Trailer Wire Connector - 3' Long part number H20042 can be ordered online at or call 1-833-496-1390 for expert service.
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Hopkins Trailer Wiring - H20042

  • Trailer Connectors
  • Trailer End Connector
  • 7 Round - Blade
  • Plug and Lead
  • 0 - 5 Feet Long
  • Hopkins

Trailer Connector RV Style 7-Way Blade with 3' lead

  • Pre-wired 7-Way Trailer Connector
  • Measures 3 feet long including connector
  • Wire gauges:
    • 14-Gauge - red, brown, green, and yellow
    • 12-Gauge - blue
    • 10-Gauge - white and black

Wiring Code
Molded Connector Function Usual Trailer Wire
White Wire Ground White Wire
Red Wire Left Turn and Brake Yellow Wire
Brown Wire Right Turn and Brake Green Wire
Green Wire Tail Lights Brown Wire
Blue Wire Brake Power Blue Wire
Black Wire 12 volt (hot lead) Black Wire
Yellow Wire Aux. -

20042 7-Way Molded Trailer Wire Connector, 3' Long

Installation Details H20042 Installation instructions

California residents: click here

Customer Reviews

7-Way Molded Trailer Wire Connector - 3' Long - H20042

Average Customer Rating:  4.6 out of 5 stars   (170 Customer Reviews)


I've had this in use for over a year and they don't build them like they use to. I use this on a gooseneck trailer and the piece of plastic behind the spade connector for the clearance lights and brakes has melted, allowing the spade connector to lose contact with the plug on the pickup. So the lights would cut off in the middle of the night and would have to wiggle the connection till I could fix it. I have an older Hopkins plug and never had this problem.

To fix the problem I ended up putting pieces of thin copper wire behind the spade and have done it twice since the plastic melted a 2nd time and once again the trailer clearance lights would quit working. Attached are before and after pictures.


Frustrated because I needed an RV harness wiring ( or Vice versa ) and salesman did not ask me details. But it just a wire color difference so all is well.


No more messing around finding the adapter for the trailer harness. Going to put this on all my trailers when I find the time.


I bought an adjustable Curt receiver and my trailer wiring ended up being a few inches to short, it was tight to begin with. I was going to buy an extension but they were around 7' long, which was to long for my needs. I chose this and wired it up the other day and it works great so far. Make sure you have the RV blade type like this connector not the pin type or it won't work obviously. As mentioned in other reviews, the wiring may be color coded different on your trailer, so be mindful of that or you'll be re-doing the connections. It looks like a sturdy and well built sealed connector, so it should last for years and it was reasonably priced.

We always recommend to test by function before connecting any wiring using a circuit tester like part # 3808. I have also included a link to one of our help articles that shows the different wiring configuration options.
-- Etrailer Expert Rachael H - 06/20/2018


Wire color scheme was totally wrong for my Tundra, it’s a poor fit in the socket and it’s a touch too short. When I first hooked it up I had my running lights as blinkers and my reverse lights controlling my brakes. AVOID

There is more than one accepted wiring color code, which is why we identify the wire color and each wires function in the product description above.
-- Etrailer Expert Mike L - 07/08/2019
Color schemes aside, this connector is intermittent after one winter. No physical damage can be seen but the cable needs to be bent a certain way for connection. Still 1 Star.
Daniel - 07/07/2020


right length easy to do work great


Product worked fine for what I needed. Plug on my tow vehicle was further away from the ball than it was on my old one. Trailer pig-tail was not quite long enough to provide slack for turns. I put the other end on this pig-tail and extended the trailer pig-tail. Worked great.


These connectors are of very high quality and make for a professional installation and appearance when used with LE$D lights and Dexter brakes. The different color of the wiring is a very minor obstacle. Using the wiring junction box really enhances the installation of the connector.

Connector is still working very well and expect to get unlimited years of service from the connector.
lwal - 05/27/2015


The product works great but the color coding is off compared to the colors on the trailer. I started hooking this up matching all of the colors.( Red on Red, Black on Black, etc.) When I plugged in the trailer in it blew a fuse. So I got online and found out that the Hopkins wiring is different then normal trailer wiring. Overall it works great but the colors should match to make it easier to hook up.

To ensure that your trailer connector is wired properly, we recommend using a circuit tester to match pins by function. Because wire colors can vary, they are not as reliable for determining functions. Improperly connected wiring can blow a fuse or cause damage to electric components. For more information, check out this helpful article:
-- Etrailer Expert Laura E - 07/22/2017


Made nicely perfect length for my trailer. The trailer I'm using it on is only a 2 place enclosed snowmobile trailer that comes with your standard 4 flat I was tired of using adapters so I changed to this plug.

That is exactly why I just ordered two pigtails. I am converting my 4 wire flat to a 7 pin and a 6 pin to a 7 pin. tired of trying to find adapters. I have 5 different trailer types and they will all have 7 pin when I am finished converting them.
-- comment by: Jim B - 09/24/2014


I drag'em so gotta replace' replacement yet


Easy to install, I've had it spliced into my boat trailer for a year now and no issues. The body has held up well with no cracks or broken plastic pieces.


You get exactly what is pictured. The 12v power and Ground (black and white) are 10 gauge, the "Aux" (which is red on this harness and purple on the ETBC7 vehicle wiring kit) is 12 gauge, and the other 4 wires are 14 gauge. The 3' length is measured from the face of the plug to the stripped ends of the seperated wires.


Wired to my Lance Camper harness to avoid having the Lance custom socket in the bed wall when I upgraded my truck. I had to run an 8 ga 12v source from the truck battery to the rear of the bed to supply lots of 12v power for the camper fridge. I didn't use the weak 12v supply from the stock truck trailer connector.


Looks well made. I have no idea if it is made in USA though. I wish etrailer would give country of origin (when not USA). MAGA!

Good quality. Easy to work with.
Dennis - 05/11/2020


Perfect fit!


After having our extension cable stolen and realizing the plug on the trailer was worn out and due for replacement, I decided to repair the end by adding a 3 foot pigtail. This accomplished both goals of adding cable length and replacing the plug end.
I used dielectric grease, butt crimp connectors and shrink tube to seal out the elements. Great product....


These connectors were high quality by a known manufacturer. I could have bought them locally but I wouldn't have gotten the expert advice and detailed information that I was able to get from eTrailer!. I talked to several people and each one was very knowledgeable. When the parts arrived, it surprised me because they came so quickly! I would readily order from them again if I needed more trailer parts. I used these connectors to adapt a Minn-Kota trolling motor to my fishing kayak and have attached some pictures showing it installed.


Wow. Very heavy duty product at a reasonable price. I purchased this for an extension harness for my pickup because the connector on the truck is located way off to the side of the hitch. I expect this product to outlast my pickup.


Excellent product. Much higher quality than I expected at this price. Online wiring guide is great. Would be good if paper copy accompanied product to avoid mistakes I made first time I connected harness. Excellent quality.


Great product and fast shipping.


Hard right turns with new truck pulled out camper electric connector just enough for some of the functions not to work. This fixed that problem. Needed some wire ends to make neat connections in the etrailer connection box. Used large zip ties instead of drilling to connect the box to trailer frame.


Just installed the 7-way molded 3' trailer connector on an older Wells Cargo Inline Snowmobile Trailer and it fit perfectly. The molded end is going to work great keeping out the salty mist from our Wisconsin highways. The wire colors don't match trailor wiring standards, but the color key code on the web site was extremely helpful. With there fast and prompt shipping, I will be using from now on. Thanx


Don't waste your time and money on this product. The pig tail was wired wrong so the larger gauge wires for things like 12v constant ground and the trailer brakes were on the smaller gauge wires and when the right turn signal was on it energized 4 other wires. I figured I would just re-arrange the wires in the pig tail and investigate why the right turn signal energized so many wires and to my surprise the plug was not accessible because it was molded around pig tail.


Had to replace old connection that was worn out not working correctly. Fit perfectly.
Thanks for your help !!!

Show More Reviews

See what our Experts say about this Hopkins Trailer Wiring

  • Installation of Hopkins 7-Way Molded Trailer Wire Connector Based on Wire Function vs. Color
    The 7-Way Molded Trailer Wire Connector - 3' Long # H20042 has different wiring colors than other connectors. The color that will connect to the reverse light function is the yellow wire of this molded connector. They label it Aux as some people choose not to use the reverse light function and add a second 12V power instead. You just want to make sure functions match on either end of the connectors. The Hopkins connectors are different than the standard colors, so you will want to make...
    view full answer...
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  • 7-Way Replacement Recommendation for Bunkhouse Camper with 6-Way Flat
    We don't have a 6-way flat connector so we don't have a way to create an adapter using one. Only solution we have would be to remove the 6-way flat and install a 7-way flat in it's place like with part # H20042.
    view full answer...
  • Replacement 7-Way and Wiring Diagram for Camper
    Sorry to hear about the vandalism of your camper. I attached a couple diagrams for 7-way trailer wiring harnesses. For a replacement 7-way we have the part # H20042 which comes with 3 feet of wire.
    view full answer...
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  • 7-Way Trailer Connector Recommendation for a Boat Trailer with Electric Over Hydraulic Brakes
    Yes, we have exactly what you need. To replace the 5-way you have on your boat trailer with a 7-way you will want the part # H20042. I attached an install and review video for you to check out.
    view full answer...
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  • How Would Trailer with 4-Way Wire to the 7-Way part # H20042
    It sounds like your current 4-way has two wires ran to the running light circuit (one for each side of the trailer) and the rest of the wiring is standard. Especially considering the order of the colors that you listed. Green is right turn/stop, yellow is left turn/stop, brown is running light, and white is ground. To wire that to the part # H20042 that you referenced would require you to use the information I just listed and compare that to the diagram picture that I attached. You would...
    view full answer...
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  • Functions of the White, Blue and Black Wires of the Replacement 7-Way H20042
    The white is ground, the blue is for the brake output circuit for the trailer's brakes and the black is for the auxiliary 12 volt circuit for the trailer. If you have no use for these circuits then they would not have to be connected to anything, you would just need to tie them up and out of the way. I attached a chart that shows the functions of each of the circuit of the connector. I attached an install video for you to check out as well.
    view full answer...
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  • Charging a Tolling Motor when Towing a Boat with a 2005 Chevy Silverado
    Given that you currently have a 7-way on your truck, the easiest adjustments to make to your trailer connector would be to change the plug to a 7-way blade, and use the power lead of the new trailer connector to charge your battery. Use half of the wires to splice into the wires on your 4-way, ground the extra wire with the white ground, and run the power lead to the battery you wish to charge. You will need trailer connector part # H20042. If you already have the wiring to complete a...
    view full answer...
  • Compatibility of Hopkins 7-way Trailer-Side Connector # H20042 with 2004 GMC Sierra 2500
    The Hopkins 7-Way Molded Trailer Connector you mentioned, part # H20042 is not a vehicle-specific item. It will work well with any vehicle that is equipped with a 7-way trailer connector as long as it is wired correctly. I have linked you to our wiring FAQ article that will run through how a 7-way is wired. Keep in mind that the # H20042 uses a non-typical wire color code, so be sure to wire it by function, not by wire color. The white wire on the connector would ground to the trailer...
    view full answer...
  • Wiring In the Hopkins 7-Way Molded Trailer Wire Connector, # H20042
    I will be glad to help you out with wiring up your trailer. To start, I will mention the electric brake wiring. There are 2 wires on the brake assemblies coming from the magnets. One will be ground and should be connected to a bare metal surface on the trailer frame, near the magnet. If the ground is too far away, it may not work properly. The other wire will connect to the blue wire on harness # H20042. This will provide the power to the brakes. The White wire is the ground and it does...
    view full answer...
  • Does Hopkins 7-Way Trailer Connector Have a Wire for Reverse Lights
    Yes, the yellow wire is labeled as auxiliary in the chart on the product page. This wire goes to the center pin which on your Dodge Ram would be the reverse lights. I assume you need this to activate the back-up solenoid for a reverse lock-out so the brakes do not engage when backing up.
    view full answer...
  • Electric Trailer Brakes Grabbing Hard on Trailer
    So there are a couple potential issues here with your trailer's electric brakes that are grabbing hard and releasing on their own. The information about other trailers working fine on the same truck is important because that means we can rule out the issue being on the truck side, and narrow it down to the trailer side. It could always be a bad ground causing an issue with the brake wiring, so start there and see if your brakes have a good ground. The other thing you will want to check...
    view full answer...
  • How To Wire 7-Way Trailer Connector On Trailer for Factory Plug
    In order to wire up the trailer to hook up to a factory 7-way trailer connector you can simply install a new end, the 7-Way Molded Trailer Wire Connector part # H20042 is what I recommend. I can't tell you what wire colors to hook where as not all trailers are the same but likely the green is right stop/turn, yellow is left stop/turn, brown is running light, white is ground, blue is brake output, black is battery charge, and yellow is reverse. If you don't have all functions you could be...
    view full answer...
  • How to Make a 7-Way to 6-Way Square Jayco Trailer Connector Adapter
    Yes, the Jayco trailers use a very unique wiring on their trailers. There is no adapter available that will go from a 7-Way vehicle side connector to a 6-Way square Jayco connector. You will need to make one using the follow parts: 7-Way trailer connector # H20042 6-Pole Square Trailer Wiring Connector Kit, # 37995 Start by identifying the wire functions of the trailer side connector so that it will be easier to wire in the 7-Way later. Connect the 7-Way wires on H20042 to the vehicle...
    view full answer...
  • Solution for Towing a European Trailer with a US Spec Tow Vehicle
    The only solution I could help you with would be the third option you listed. You would want a trailer side 7-way like part # H20042 to wire up to an EU socket found local to create an adapter to use your US spec vehicle with EU trailer wiring. I attached a chart that labels the functions of the wires on this connector. The Adapter 7 Way (Blade) to 7 Way (Round Pin) # 47595 that you referenced is not an adapter for EU wiring nor do we offer any adapters for EU trailers or vehicles.
    view full answer...
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  • Connecting a Jayco 6-Way Square Trailer Connector to a 2011 Nissan Pathfinder with 7-Way Connector
    The square Jayco plug is specific to Jayco trailers so in terms of adapters # 30104 is it. What I recommend is to replace the connector on the Jayco trailer with a 7-Way trailer end, like # H20042, so you will not have to worry about adapters anymore. Be sure to wire in the 7-Way by function and not by wire color. I have included a link to an FAQ article on trailer wiring that shows the correct configurations of various trailer connectors that should help. The wiring code for the 7-Way...
    view full answer...
  • 4-Flat to 6-Way Square Wiring Adapter for a Flagstaff Tent Trailer and Toyota Rav4
    We have the Adapter 4 Way Flat to 6 Way Square for Jayco, # 30104, but it states it is for Jayco RVs only. However, I spoke with my contact at Cequent, the manufacturer, and he stated that this adapter was used on the Tent type trailers. He seemed to believe that it would work. Wiring the trailer for a 7-Way connection is probably the best option to avoid future compatibility issues. You can use 7-Way Molded Trailer Wire Connector, # H20042, and use the wires that come out of the back...
    view full answer...
  • Availability of a Replacement Jayco 6-Way Trailer Side Connector
    Jayco is the only manufacturer that uses that type of 6-Way connector. We do not have a replacement that is going to work. Since yours is broken this is the perfect time to install a 7-Way connector on the trailer so you do not have to mess with various adapters. If you do not want to change to a 7-Way on the trailer then you would need to get a replacement trailer side Jayco 6-Way from Jayco. But to add a 7-Way RV style connector to the trailer you can use something like # H20042. You...
    view full answer...
  • Replacement Trailer Wiring Solution for 1997 Jayco Eagle 10 LD with Square 6-Way
    Jayco is the only manufacturer that uses that type of 6-Way connector. We do not have a replacement that is going to work. Since yours is broken this is the perfect time to install a 7-Way connector on the trailer so you do not have to mess with various adapters. If you do not want to change to a 7-Way on the trailer then you would need to get a an adapter from Jayco. But to add a 7-Way RV style connector to the trailer you can use something like # H20042. You will need to determine what...
    view full answer...
  • How to Tow a Euro Trailer with a US Vehicle
    I do have an option for you but there is no easy way to tow a trailer with a Euro 7-way using a vehicle with a US 7-way. They do not make any sort of adapter for this to my knowledge and the only option I can offer you is to remove the Euro 7-way trailer connector from the trailer and install a US 7-way trailer connector. For this you are going to need both a converter box part # 118158 and trailer connector part # H20042. On your trailer there should be the following wires: Yellow: Left...
    view full answer...
  • Have Running Lights and Trailer Brakes Function Properly but No Brake Lights or Turn Signals.
    Since all of the functions on the truck are working properly, and you have narrowed down the wiring problem to between the junction box and trailer connector, I believe you have a problem with the trailer side connector itself. Check the inside of the trailer connector for corrosion. If you find green and/or white corrosion that will be where the problem lies. You will need to clean this corrosion out and make sure the connections are secure. Sometimes the corrosion is rather stubborn...
    view full answer...
  • Adaption a 7-Way Blade Style Connector to a 6-Way Square Connector on a Trailer
    Using multiple adapters just increases the chance that something could go wrong. The best solution is to use an adapter to go from a 7-Way blade style to the 6-Pole square. To do that though an adapter would have to be fabricated. All you will need is a trailer side 7-Way, # H20042, and a vehicle side 6-Way square. For the 6-Way square you would need # 37995 but only use the vehicle end to wire to the wires on the 7-Way, # H20042. On the 7-Way the wire functions are: White = ground Red...
    view full answer...
  • Can an Electric Trailer Jack be Powered Using a 7-Way Connector on a Truck
    The wiring on a trailer connector and the tow package wiring on a vehicle is not really rated high enough and the wire gauge is not large enough to properly power an electric trailer jack. You would want to mount a battery on the trailer and use it to power the winch. To provide a maintenance charge to the battery what you could do is replace the 4-Way on the trailer with a 7-Way, such as # H20042, and run the black wire from it to the positive battery terminal. This will keep the battery...
    view full answer...
  • Recommended Solution for Towing European Trailer with US Vehicle
    The best thing I can recommend you do is you would want a trailer side 7-way like part # H20042 to wire up to an EU socket found local to create an adapter to use your US spec vehicle with EU trailer wiring. I attached a chart that labels the functions of the wires on this connector for you to reference. To gain all the function that a US 7-way carries you will also need to adapt your US 4-way into a 7-way blade to be compatible with the # H20042. For this I recommend the # ETBC7, it's...
    view full answer...
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  • Can 4-Way To 6-Way Adapter For Jayco Trailers Charge Trailer Battery
    Using the Hidden Hitch Adapter 4 Way Flat to 6 Way Square for Jayco, part # 30104, will only provide lighting functions. It will give you turn signals, brake lights, and running lights. It will not provide power to charge your trailer battery. In order to get power to the trailer battery you will need to remove the connector on the trailer and replace it with a 7-way connector like part # H20042. This will plug into the 7-way on your towing vehicle. You will want to make sure you test...
    view full answer...

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