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Hopkins Heavy-Duty Trailer Coiled Extension - 4-Pole Round - with Nite-Glow

Hopkins Heavy-Duty Trailer Coiled Extension - 4-Pole Round - with Nite-Glow

Item # HM47045
Our Price: $40.85
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Shipping Weight: 0.91 lbs
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Great when pulling your vehicle with a tow bar, this 4 pole round extension has connectors that light up, making it easy to hook-up your vehicle at night. Coiled design keeps wires from dragging on the ground. 1-800-940-8924 to order Hopkins accessories and parts part number HM47045 or order online at Free expert support on all Hopkins products. Great prices and Fastest Shipping for Hopkins Heavy-Duty Trailer Coiled Extension - 4-Pole Round - with Nite-Glow. Accessories and Parts reviews from real customers.
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  • Reviews (17)
  • Q & A (0)
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  • Why etrailer?

Hopkins Accessories and Parts - HM47045

  • Tow Bar Wiring
  • Extensions
  • 4 Round to 4 Round
  • Hopkins
  • Coiled Cord

Great when pulling your vehicle with a tow bar, this 4 pole round extension has connectors that light up, making it easy to hook-up your vehicle at night. Coiled design keeps wires from dragging on the ground.


  • Heavy-duty, coiled cable
    • Weatherproof jacketing
  • Easy-grip, translucent Nite Glow connectors
    • Light up when connected to confirm continuity
    • Assist with hookup in the dark
  • Tin-plated terminals for corrosion resistance


  • 8' Cable when stretched
  • 4-Pole round to 4-pole round

Flex Coil Adapters provide increased durability and the additional length that may be necessary to reach between the tow vehicle's socket and the trailer/towed vehicle's plug.

In addition, Flex-Coil Adapters with Nite Glow illuminate on activation of the tail light function. This enables the user to find the electrical connection in the dark and shows that the vehicle's trailer wiring system is working properly.

47045 Hopkins Trailer Connector, 4-way Round Coiled Extension with Nite-Glow Plugs

California residents: click here

Customer Satisfaction Score:

Customer Reviews

Hopkins Heavy-Duty Trailer Coiled Extension - 4-Pole Round - with Nite-Glow - HM47045

Average Customer Rating:  4.6 out of 5 stars   (17 Customer Reviews)

Great when pulling your vehicle with a tow bar, this 4 pole round extension has connectors that light up, making it easy to hook-up your vehicle at night. Coiled design keeps wires from dragging on the ground.


I hope this replacement can hold up longer than the first one. I have had a recurring problem with the cord, losing conductivity when plugged in & in use. If you slightly stretch out the cord, the conductivity will short out; If the cord is kept in retracted position - conductivity is maintained. This is used on a tow vehicle, behind a class a Motorhone.

This sounds defective. Customer Service will reach out to you.
-- Etrailer Expert Sierra K - 10/28/2021
Hello- need to keep a eye on both cord receptacles: specifically the union where the plug meets the actual cord. If this seems to be briddle or somehow frayed- check for proper conductivity. Also- I would be careful when driving iiin the rain. This is the 3rd cord over time for me I use this on a class a diesel pusher Motorhome. Thx
Colin - 10/28/2022


Great molded product for 4 wire motor homes. Be sure and order the matching receptacle for your tow vehicle that fits the plug here on this site. The ones you can purchase locally from NAPA or auto stores WILL NOT fit.
Most local camper stores do not stock since they have moved on to the 7 wire system.


This product was packaged very well and arrived in a reasonable amount of time with economy shipping. It was not what I thought I was ordering, but that was my fault. Seems there are two different kinds of 4-wire plug sizes. One must be for automotive and one for HD trucks. This harness would not plug into my truck female receptacle; it was too small and the pin spacing too close. I had to cut the plug off and wire in the proper size plug that I purchased locally. Of coarse I lost the feature of the plug lighting up when connected, but again, that was my fault for not knowing there were different plug sizes. All-in-all, I'm not terribly disappointed. Lesson learned.


I was looking for a hard to find extension that was not related to trailers. After two days of scouring the Internet I found Their site was easy to navigate and the purchase made easy. Lastly my package showed up before the estimated ship date.


Worked great


Not only is the cable excellent, but the service by etrailer was outstanding. Due to delivery service problems I did not receive the first cable and they sent me another to my next address and refunded for the first when they received it back. I have used them before and will definitely use them again.


Very well made product. The cable ends are super hard plastic and the cabling itself appears to be quite tough. The metal connectors inside the ends are well made, and the ends fit tight into the plug receptacle. Sure easy to find by the colors!


Everything I've purchased at etrailer has been perfect!


Outstanding, Not only is it still working great after thousands of miles and many connections and disconnections. I also have discovered that all my poor connections have disappeared.
Dean - 11/05/2022


good construction , could be a little longer,another foot longer would enhance useage and less strain on ends.


worked like it was advertised. No special conections were necessary








Excellent product, shipping, and customer service.


Good pricing, easy to find parts on site and shipped quickly



See what our Experts say about this Hopkins Accessories and Parts

  • Why Does the Hopkins Heavy-Duty Trailer Coiled Extension with Nite-Glow Flash With Turn Signals
    I spoke with Hopkins about the Hopkins Heavy-Duty Trailer Coiled Extension part # HM47045 and what you are going to need to do is test the running light wire just before the connector. If you get a pulse signal when the turn signal is applied then you have an issue with the vehicle wiring but if not then the extension is bad and will need to be replaced.
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  • Is Pollak 4-Pole Round Trailer Wiring Socket # PK11404 Compatible with Coiled Extension # HM47045
    Yes, the Pollak Heavy-Duty, 4-Pole, Round Pin Trailer Wiring Socket, # PK11404, and the Hopkins Heavy-Duty Trailer Coiled Extension, # HM47045, are compatible parts. You can see a typical wiring description on the product page for the PK11404, under specs. White would be ground return, green is right turn and brake lights, yellow/red is left turn and brake lights, and brown is taillights. Essentially, there is no standard or agreed upon diagram of which function should go with which pin...
    view full answer...
  • What Is the Size of the Socket On the Hopkins Heavy-Duty Trailer Coiled Extension HM47045
    The Hopkins Heavy-Duty Trailer Coiled Extension part # HM47045 has two standard 4-round trailer connector sockets on each end which are both 13/16" diameter. This is more than likely what you have now as I am not aware of there being multiple different diameters for a standard 4-round trailer connector socket. That said, I can confirm for a fact the Pollak Heavy-Duty 4-Pole Round Pin Socket part # PK11410 will fit this extension harness.
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  • What is the Wire Gauge Used in Hopkins Heavy-Duty Trailer Coiled Extension - 4-Pole Round
    The Hopkins Coiled Extensions with the Nite-Blow such as # HM47045 use 16 gauge wires on the inside. Trailer wiring harnesses usually use 16 to 18 gauge wire for lighting functions and heavier wire for components that draw more amperage. On a 4-Way, you should have left and right turn signals/brake lights, running lights, and a ground so 16 gauge wire will work fine. But if it is for something other than lights then you would likely need to make an extension. We have jacketed 4-wire, #...
    view full answer...
  • 4-Round to 4-Round Tow Bar Wiring Cable
    I have a couple of options that might work for you but we don't carry just the cord from part # RM-98164 on its own. Instead we do have part # RM-1064-B which doesn't have either connector on it. We also carry part # HM47045 which is the same type of cable, 4-round to 4-round, but obvioulsy isn't the blue Roadmaster cord.
    view full answer...
  • How to Wire Up a Tow Vehicle that has a Separate 6-Way to Tow a Vehicle with a 4-Way Flat
    The easiest way to do what you need is to convert the signal on your RV's connector to a combined circuit and then install a 4-way on your RV like part # PK11404 in place of the 6-way. For that you would want to start with a signal converter like part # RM-732. You will need to wire up the RV trailer wiring just like the label of the converter recommends. You'll notice that the running lights aren't mentioned on the label, that's because it bypasses the converter and runs straight to the...
    view full answer...
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Info for this part was:

Employee Michael H
Expert Research:
Michael H
Employee Dustin K
Video Edited:
Dustin K
Employee Cole B
Installed by:
Cole B
Employee David F
Installed by:
David F
Employee Alexander C
Updated by:
Alexander C

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