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5-Way Flat Trailer Connector In-Line Circuit Tester

5-Way Flat Trailer Connector In-Line Circuit Tester

Item # 20115
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Tow Ready Tow Function Tester Wiring - 20115
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Lowest Prices for the best wiring from Tow Ready. 5-Way Flat Trailer Connector In-Line Circuit Tester part number 20115 can be ordered online at etrailer.com or call 800-298-8924 for expert service.
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  • Reviews (14)
  • Q & A (9)
  • Videos (2)
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Tow Ready Wiring - 20115

  • Tools for Wiring
  • Testers
  • Tow Ready
  • Tow Function Tester

Tow Ready 5-Flat Car End Tester by Draw-Tite, Hidden Hitch and Reese

A circuit tester that plugs into the 5-way trailer connector on the vehicle. The lights let you know what functions (brake, turn, tail, reverse, and stop) are working properly and what functions aren't. Inline circuit tester allows you to plug the trailer connector in on the other side.

20115 5-Way Flat Trailer Connector In-Line Circuit Tester

Installation Details 20115 Installation instructions

Video of 5-Way Flat Trailer Connector In-Line Circuit Tester

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

Video Transcript for Tow Ready 5 Way Flat Trailer Connector Circuit Tester Review

Today we're going to be taking a look at the tow-ready 4-pole or 5-pole inline flat trailer connector circuit tester. As you can see our tester, this is going to be a completely 1-piece unit here. We're not going to have different pieces clicked together or anything. That gives us really good dependability. Each of our connection areas here is going to have some corrosion-resistant material there to help prevent any rusting or corrosion. Light's molded right in, so we won't have to worry about those coming loose or anything. It's kind of a rubberized material, so it's going to be good and rugged.

The reviews say it's really dependable. It's going to last a good long time. Nice thing about the cap, it's also been molded on so we don't have to worry about losing that or it falling off. It'll always stay permanently attached for us. The pass-through so we're actually able to plug our trailer in on the other side of it, if we just want to leave it in place. If we want to store it in the car, simply remove it and plug our trailer in normally. But this is going to test out, 1, our ground to make sure we've got a good ground, but also it's going to test out our taillight, left turn signal, right turn signal, and also the backup signal that's labeled as an A.

That's going to be for a lot of marine applications. That's going to be if you have a 5 pole. If you have a 4 pole, it's going to be the first 4. When you step on the brakes, you want to see the 2 in the middle there light up. It plugs directly inline as we said, with any 4 or 5-pole application. This is just going to slide in just like that.

Then we can either cap that off if we're just going to be running tests or actually want to use it as an inline tester so we can monitor that. We can plug our trailer in right there nice and easy. Let's get it plugged into our vehicle here. I'm using the aid of a 7-pole round to a 5-pole adapter that we sell here at etrailer. We'll start with our running lights. Left blinker. Right blinker.

Brakes. And reverse. This is going to be a great, quick, and easy way to test our wiring to make sure everything's working before we get on the road, or monitor it as we head down the road to make sure we don't have any shorts. As far as measurements are concerned, you can see we're going to have a width . That's about an inch and 3/4. Then the total of what we're going to add to our actual plug is going to be about 2 inches. If space is an issue for you, definitely want to check and make sure you've got that extra 2 inches that you need that then you can simply plug in and head down the road. That'll complete our look at the tow-ready 4-pole and 5-pole flat circuit tester.

Customer Reviews

5-Way Flat Trailer Connector In-Line Circuit Tester - 20115

Average Customer Rating:  4.9 out of 5 stars   (14 Customer Reviews)

- 20115

It's nice to order a list of parts from one source online for my project trailer. 658725

- 20115

Simple but much needed. No need to have a friend confirm your vehicle's electrical inputs, run back and forth between the vehicle and trailer and it's a great pre-trip item too. 584689

- 20115

Works great. 574644

- 20115

The only 5 wire LED I could find. Glad to find this product beats carrying a test light when towing. Have not tried it yet but I have no doubt it will be great. 425363

- 20115

Good quality shipped in timely manner. Price is ok. 425058

- 20115

Got it fairly quickly, had status of shipping the same day. Got it and it works as discribed . 340363

Awesome, I have used it on and off for a year and it works as promised.
Bart - 02/10/2018


- 20115

great 262332

- 20115

Lights show for turn signals, lights and brakes when activated. I'm not sure how this helps you test the back-up lights that you connect to the blue wire. Worked fine. 190780

- 20115

cool tool to have in the car. nice job! 157190

- 20115

Works great... handy little tool. Will come in handy. 133415

- 20115

Product is exactly what I needed. Value shipping was poor. The web site did not mention that value shipping could take 1-1/2 weeks. 131313

- 20115

Exactly what I was looking for. 130108

- 20115

Works as expected. The LEDs are nice and bright, making it easy to see which functions are being activated. 122136

- 20115

Products arrived promptly and the install went smoothly. The hard part was getting access to the area in my Highlander where the wire had to be routed. Everything else went like clockwork. The instructional video was a great help. Thanks!!! 13283


Ask the Experts about this Tow Ready Wiring

  • How to Test the Trailer Light Functions of a Trailer with a 4-Way
    There is, but I will warn you it's pretty expensive. The Hopkins Tow Doctor Trailer End Test Unit # HM50928 is designed to test the connector on a trailer for function and would be perfect for what you are trying to do. Check out the review video I attached. A much more inexpensive option would be to use a jumper wire from a car battery's positive post to put voltage on all of the pins of your trailer's connector. You would need to test the three male pins next to the female pin....
    view full answer...
  • Do You Carry a Dust Cover for 5-Way Flat Trailer Connector
    We do offer a dust cover and tester combination, part # 20115 that may work for your needs. Or for a plain cover you can use part # 20118.
    view full answer...
  • Recommended Way to Test Trailer Lighting With a Car Battery to a 4-Way Trailer Connector
    The 5-way flat trailer connector in-line circuit tester # 20115 you referenced won't be needed. You would need to have a 12V power source and your jumper wire which will let you know if you have working trailer lights. The most common gauge trailer light wire for 4-way or 5-way trailer connector is 14-16. You will need to make sure that you secure the ground wire to the trailer frame. See picture to the right. I recommend a circuit tester such as # 40376, if you are checking for...
    view full answer...
  • Can 5-Way Trailer Connector Circuit Tester be Left Plugged In While Driving
    Yes, you can leave the tester, # 20115, plugged in while traveling. It is not going to fall out, especially when you are towing a trailer since it would be sandwiched in between the vehicle side connector and the trailer connector. But you might find that leaving it in place is not the best idea because you are essentially adding another link in the connection between the trailer and the vehicle.
    view full answer...
  • 4 and 5 Pole Trailer End Connectors
    We have trailer end connectors in both 4 and 5 pole configurations. Also, we do carry covers that can be added to 4 pole connectors and boxes that can be mounted on the trailer to store connectors in. We also have circuit testers that can be put in line with the vehicle and trailer or just plugged into the vehicle. The 5 way circuit tester, 20115, is an in-line model and should work for both 4 and 5 pole connectors. I have posted links below for your convenience.
    view full answer...
  • Connector Protector for a 5-Pole Flat Wiring Harness
    The 4 and 5-Flat Trailer Connector Mounting Box, Part # RP74641, is a very good 5-flat protector. You could also use the 5-Way Flat Trailer Connector In-Line Circuit Tester, part # 20115, which has a protective cover on the end that is not connected to the vehicle.
    view full answer...
  • Longer 5-Way Trailer Wiring Connector with Lead
    The longest 5-way connector for a trailer that has built in circuit testers is the part # HM47913 that you referenced. For a 48 inch 5-way and lead we have the part # 20017 but it does not have the circuit testers. We do have a 5-way tester too that you could use with this as part # 20115.
    view full answer...
  • Trailer Side 5-Way Cover for Wiring Connection Availability
    For a 5-way trailer side we don't have the cover alone. You can use the Hopkins Endurance 5-Way Flat Trailer Connector - Trailer End - Ergonomic Design # HM47910 which has the integrated cover, or you can use a 5-Way Flat Trailer Connector In-Line Circuit Tester # 20115 to cover those connections. For wiring with integrated covers for both sides of the connection, you can use the Hopkins Endurance 5-Way Flat Trailer Wiring Kit - Vehicle and Trailer Ends - Ergonomic Design # HM47890.
    view full answer...
  • Availability of 5-Way Tralier Connector Cover
    We currently carry one 5-way cover, part # 20115. It also has an integrated LED Circuit tester that you can use to make sure the wiring on your vehicle is working properly.
    view full answer...

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Info for this part was:

Expert Research:
Patrick B
Expert Research:
Michael H
Video Edited:
Jacob T
Video by:
Kathleen M
Updated by:
Laura H
Updated by:
Isabelle B
Installed by:
Cole B
Installed by:
Randy B

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