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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
Our Price: $9.42
You Save: 62%
Trailer Wiring
Shipping Weight: 0.18 lbs
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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. Great Prices for the best trailer wiring from Hopkins. Hopkins 4-Way Flat Trailer Connector w/ LED Test Lights - Trailer End - 24" part number HM48133 can be ordered online at or call 1-800-940-8924 for expert service.
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  • Reviews (14)
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Hopkins Trailer Wiring - HM48133

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

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

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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   (14 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.


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



Working Perfectly!!


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

Ole A.


Great products! Super service! etrailer is my place for ever thang trailer related.


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.


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.


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.


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


Easy to install and get it connected fast to old pigtail


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


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


Items were as described and fast shippi ng.


On time
Every time


fast shipping, plug was as advertized




See what our Experts say about this Hopkins Trailer Wiring

  • 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.
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  • Right Turn Signal Does Not Work on Trailer
    There's a few options here, either a ground or bad wire, like you said, or the 4-way on your trailer has corroded. So start easy and check your trailer connector for corrosion, which can be green or white in color. A build-up of corrosion can interfere with the signals getting through the connectors so if it is present you are going to need to replace the trailer connector with a new 4-way, either # HM48133 or # HM38134. Then you can check and see if you have a damaged wire (though I doubt...
    view full answer...
  • 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...
  • Troubleshooting Lights on Bike Rack on 2022 4Runner Towed by Motorhome Not Working
    From what you are describing it sounds like you have a bad connector or a bad ground connection. Resistors are not going to solve the problem. I would double check the ground wire and also make sure that it is secure on a clean, bare metal surface. If everything checks out with your ground connection, the issue may also be your trailer connector since it has jumped pins with the different lights not working. Since you checked your vehicle side connector the trailer end connector is probably...
    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...
  • 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...
  • 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 Trailer...
    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...
  • 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...
  • 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...
  • 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...
  • Replacement Wiring For Round Tube Stainless Steel Trailer Hitch Receiver Step With Light CR-600LED
    You will need to wire the Hopkins 4-Way Flat Trailer Connector # HM48133 to the Replacement LED Strip # CR-600L-LED. There is not a harness with both connectors as neither end will fit through the small hole in the Round Tube Stainless Steel Trailer Hitch Receiver Step # CR-600LED. I recommend using Deka Heat Shrink Butt Connectors # DW05743-5 to seal the connector inside the step since water can get inside the step.
    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 inches...
    view full answer...
  • Parts Needed To Add Running Lights To a Hitch Mounted Folding Cargo Carrier
    I have a couple options you might consider. First is the easiest and would involve the Auxiliary Lights # C53201. The lights themselves adhere with double sided tape to your cargo carrier and the wiring can easily be run through your center post to keep everything tidy. These lights are going to function as running lights, turn signals and brake lights. If you prefer to only use marker lights you could cut off the 2 male terminals on the connector which activate the turn/brake lights. If...
    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. If...
    view full answer...
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Info for this part was:

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

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