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Hopkins 4-Way Flat Trailer Connector w/ LED Test Lights - Trailer End - 24"

Hopkins 4-Way Flat Trailer Connector w/ LED Test Lights - Trailer End - 24"

Item # HM48133
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HM48133 - Plug and Lead Hopkins Wiring
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Built-in LED lights on this 4-way flat connector let you know if power is being received from the tow vehicle. Separate lights illuminate to verify power to each function on your trailer for easy troubleshooting. Easy-to-grip, plastic construction. Lowest Prices for the best wiring from Hopkins. Hopkins 4-Way Flat Trailer Connector w/ LED Test Lights - Trailer End - 24" part number HM48133 can be ordered online at etrailer.com or call 800-298-8924 for expert service.
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  • Reviews (11)
  • Q & A (11)
  • Videos (1)
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Hopkins Wiring - HM48133

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

Built-in LED lights on this 4-way flat connector let you know if power is being received from the tow vehicle. Separate lights illuminate to verify power to each function on your trailer for easy troubleshooting. Easy-to-grip, plastic construction.


  • 4-Way flat trailer-end connector plugs into the 4-way flat on your vehicle
  • Built-in, red LED lights offer easy troubleshooting
    • Illuminate to verify that the connector is receiving power from the tow vehicle
    • Labeled for each function on your trailer
  • Easy-to-grip tabs allow for simple plug in and disconnect
  • Durable plastic construction
  • Corrosion-resistant terminals withstand the elements
    • Terminal grease is included


  • Wiring harness length: 24"
  • Wiring configuration:
    • Green: right turn signal (RT)
    • Yellow: left turn signal (LT)
    • White: ground
    • Brown: tail light and side marker lights (TM)
  • 90-Day limited warranty

Reduce the frustration associated with troubleshooting trailer wiring problems with this lighted 4-way connector. It has built-in LED lights that help you determine quickly and easily if the issue is with your tow vehicle or your trailer. Just plug the connector into the 4-way flat on your vehicle. No need for separate testing tools. Then activate each function on your vehicle and a red light will come on if power for that function is being received by the connector. If there is power going into the connector for all of the functions, then you know that the problem is on the trailer end and you will need to check your trailer's wiring. Each function except for ground is represented by a separate light and the functions are labeled for easy identification.

48133 Hopkins Plastic Trailer Connector with LED Test Lights - 4 Way Flat

California residents: click here

Video of Hopkins 4-Way Flat Trailer Connector w/ LED Test Lights - Trailer End - 24"

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

Video Transcript for Hopkins Wiring - Trailer Connectors - HM48133 Review

Today we're going to be reviewing part number HM48133, this is the Hopkins 4-Way Flat Trailer Connector with the LED Test Lights. Now the 4-Way Flat Trailer End Connector is going to plug into the 4-way flat on your vehicle. It's going to feature the built in red LED lights. These are going to offer easy troubleshooting. They're going to illuminate to verify that the connector's receiving power from the tow vehicle and they are labeled for each function on your trailer. The plug here is a nice, easy to grip, tabs here on the side, so that's going to allow for a simple plug in and disconnect. Get a nice secure grip on the finger tabs there.

It's also got a nice little textured surface on this area as well for that same reason. Now this going to be made from a durable plastic construction. Everything's going to be sealed. It's got a nice rubber coating on it, so again, it allows us to get a nice, easy grip. It's going to be weather resistant, so it's going to stand up well against the elements. The terminals are going to be corrosion resistant design, so they're going to withstand the elements as well.

Now all the wires are going to be labeled with their function: your white wire's going to be your ground, yellow wire's going to be for your left turn, green is going to be for your right turn, and then brown is going be for the taillight and side marker lights. The length that this going to offer is going to be 24 inches. I'd like to go ahead and hook it up to our external power source, that way you can see the LED lights function and help us determine whether or not we're getting power to the correct signals. You can see here I just have the ground hooked up, as well as my taillight and side marker light, so that's going to be this light right here. Now if I connect, I'm going to do our left turn, so you can see there now I have two indicators shinning. I'll go ahead and throw in the other turn signal as well and this going to have all three indicators sending out a nice, strong, consistent signal. That's going to do it for our look at part number HM48133, this is the Hopkins 4-Way Flat Trailer Connector with the LED Test Lights.


Customer Reviews

Hopkins 4-Way Flat Trailer Connector w/ LED Test Lights - Trailer End - 24" - HM48133

Average Customer Rating:  5.0 out of 5 stars   (11 Customer Reviews)

Built-in LED lights on this 4-way flat connector let you know if power is being received from the tow vehicle. Separate lights illuminate to verify power to each function on your trailer for easy troubleshooting. Easy-to-grip, plastic construction.

- HM48133

I really like the built-in LEDs on this harness. This will help when a light isn't working and I'm not sure if it's from the vehicle or on the trailer. 327415

- HM48133

These guys are the best! Just about every product imaginable, super service. Obtain alla my trailer stuff from etrailer. 320773

Great products! Super service! etrailer is my place for ever thang trailer related.
Ole G - 12/09/2017


- HM48133

Needed a replacement flat four harness for my motorcycle trailer. etrailer helped me to chose the correct product for my needs and rapidly processed and shipped my order. I tell all my friends if you have needs for your trailer, etrailer will solve your problems quickly and professionally. 698124

- HM48133

On time Every time 618024

- HM48133

Easy order, quick deliver, order correct, who could ask for more? 579011

- HM48133

Very high quality plug and wiring. The led lights are awesome 520796

Working Perfectly!!
Richard - 06/16/2019


- HM48133

Have not installed the connectors but they are what I ordered. Thanks 471143

- HM48133

Items were as described and fast shippi ng. 405855

- HM48133

fast shipping, plug was as advertized 314290

- HM48133

Calling e- trailer is like calling a friend, curtious , friendly , and aim to please. Haven't used any of the items from my order yet, I will shortly . The order was on time and wrapped so good nothing was damaged .I will definitely call e- trailer for my next order. 291893

- HM48133

Got what I ordered great site good info & video shipping was good also. 266907


Ask the Experts about this Hopkins Wiring

  • What Wire Gauge are Hopkins 4-Way Harness and Optronics 4-Way Harness?
    All of the wires on the Hopkins 4-Way Flat Trailer Connector # HM48133 are 18 gauge except for the ground wire, which is 16 gauge. As for the Optronics 20 ft. Wishbone 4-Way Trailer Wiring Harness # A20WB all of the wires are 20-AWG gauge. I've added links to video reviews of both products for you to take a look at.
    view full answer...
  • Can the 4-Way part # HM48133 Attach to Trailer with 2 Brown Wires
    Your trailer has two brown wires because the running light circuit goes to both sides of your trailer. You would just want to connect both wires into one end of a butt connector like part # 05732-2 and then have the single brown wire of the # HM48133 run to the other side. Be sure to crimp these connections very tight.
    view full answer...
  • Replacement 4 Way Connector for ATV Trailer
    To replace the trailer side 4 way connection I recommend using the Hopkins 4-way Flat Trailer Connector with LED Test Lights # HM48133 . You will be able to hardwire this connector in to the wires on your trailer in the same manner that the previous connector was wired. This 4 way comes with LED test lights already installed to let you know if there are any issues with your connection upon installation and anytime after. If you need any butt connectors, you can use # DW05743-5 (18 gauge-Green/Brown/Yellow...
    view full answer...
  • What Gauge Wire is Used On Hopkins 4-Way Flat Trailer Connector w/ LED Test Lights
    The wires that are used on the Hopkins 4-Way Flat Trailer Connector, part # HM48133. The white ground wire is a 16-gauge wire and the balance of the wires on the harness are 18-gauge.
    view full answer...
  • Replacement Parts for 1970s Camper Frame with Dayton Fayette Axles
    The Lippert Components Heavy-Duty Replacement Shock - Yellow # LC283280 is 8.625 inches compressed and 13.5 inches fully extended. Your current suspension may extend and retract slightly further but the shocks will be a good replacement based on the actual shock absorbing as long as they will fit your brackets. Unfortunately we don't have any info on your axle or hubs, so to help, I will need to get the bearing numbers printed on the face of your inner and outer bearing of one hub....
    view full answer...
  • Recommended 4-Way Trailer Connection Wiring On Sea Doo Challenger 180 Trailer
    For your Sea Doo Challenger 180 Trailer, I recommend the 4-Flat Connector Wishbone Style - Trailer End # W002230. This harness is a wishbone which means there are separate tail/running light wires sent to each side of the trailer so no jumper wire is required across your frame. I've attached a video of this installation for you and have also attached a wiring article to assist. If you would rather splice your 8 wire system into a 4 way connector, you can use the Hopkins 4-Way Flat...
    view full answer...
  • Best Trailer Hitch for a 2018 Highland Ridge Open Range 5th Wheel Trailer
    The trailer hitch I recommend you use on the back of your 2018 Highland Ridge Open Range Light LF291RLS to mount bikes or pull a trailer is the Adjustable Width Trailer Hitch Receiver part # 13703. The Adjustable Width Trailer Hitch Receiver is the most popular trailer hitch we have for trailers because it fits so many different types and allows for the receiver tube to be placed in the best position to ensure you don't have any clearance issues with a bike rack for example. It offers easy...
    view full answer...
  • Availability of 4-Way Wishbone Wiring Harness with Shorter Wire Lead
    The wishbone harness with the shortest amount of wire lead has 20 feet of wire and a 30 inch ground wire, the Optronics 20 Foot Wishbone 4-Way Trailer Wiring Harness # A20WB. I wish we had a shorter option for you but our manufacturers don't offer a wishbone harness with a shorter lead. I double checked with Optronics and the 20 ft lead is the shortest they offer with a wishbone harness. If you'd rather use a connector with a shorter lead, the connector with a lead closest to the 18...
    view full answer...
  • Cargo Carrier, Light Kit, and Wiring Harness for a 2000 Honda Accord
    I will be happy to help you out. First, since all of the trailer hitches for the 2000 Honda Accord are Class I hitches you will need a cargo carrier that is rated for a Class I hitch. I have included a link to the available options for you. You will need to have a 4-Way flat connector on your Accord to activate a license plate light. If you do not already have a 4-Way you can add one using # 43105. Then you could use license plate mounting bracket and light # PM436B. The power wire can...
    view full answer...
  • How to Make Third Brake Light Adapter for Cargo Carrier
    Since your trailer wiring will have the stop and turn signal circuits combined onto one wire you'll need a converter to isolate out the stop circuit for adding an additional brake light. For that you'd want the part # 118158 wired to your trailer wiring and the red wire would carry the circuit needed for the third brake light. You can make a wiring kit for your cargo carrier using a 4-way connector like the part # HM48133 wired to the # 118158 and mounted to your carrier and you'd have...
    view full answer...
  • Availability of 4-Flat Trailer End Connector
    There are 4-flat connectors which are exactly the same as the Reese part you mentioned, though the Reese 74124 is not available. The Draw-Tite # 18004 is a 12" 4-flat trailer end connector that even comes with four wire caps for attachment. There are other lengths of 4-flat trailer connectors as well, such as the 2' Hopkins # HM48133, 4' Wesbar # W787264 or 20' Optronics # A20WB. Each of these has the same functions as the Reese 74124. I've attached links to video reviews of each product...
    view full answer...

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Info for this part was:

Edited by:
Lindsey S
Expert Research:
Jameson C
Expert Research:
Jeffrey L
Written by:
Chelsea B
Updated by:
Alexander C

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