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Curt LED 4-Way Flat Connector (Vehicle End) Tester

Curt LED 4-Way Flat Connector (Vehicle End) Tester

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I26 - Tow Function Tester Curt Tools for Wiring
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Lowest Prices for the best wiring from Curt. Curt LED 4-Way Flat Connector (Vehicle End) Tester part number I26 can be ordered online at etrailer.com or call 800-298-8924 for expert service.
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Curt LED 4-Way Flat Connector Tester

This circuit tester plugs into the four-way trailer connector on the vehicle. The bright LED lights analyze the trailer connections and indicate which functions (tail, left turn and stop, right turn and stop) are working properly and which are not.

I-26 Curt LED 4-Way Flat Connector Circuit Tester

58260 Curt LED 4-Way Flat Connector (Vehicle End) Tester

Item # I26

Video of Curt LED 4-Way Flat Connector (Vehicle End) Tester

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

Video Transcript for Curt Wiring - Tools for Wiring - I26 Review

Speaker 1: Today, we're taking a look at the CURT LED 4-Way Flat Connector Tester for the vehicle end. This small compact circuit tester plugs into the four-way trailer connector on your vehicle. It has the bright LED lights that analyze the trailer connections and indicate which functions are working properly and which are not. That way, you can take care of the problem. The LEDs have a protective casing over them to ensure that they don't get damaged. When you plug this in, this LED light right here will light up for the taillights.

This one right here is for the left turn and this one is for the right turn. Then when you apply the brakes, both the left turn and the right turn LEDs will light up. That's if everything is working as it should.Now, the housing is made from a durable plastic construction, does have the little holder here so you could put it directly on a key chain or you could hang it on a nail in your shop or garage. Terminals are corrosion resistant and it does have a nice easy grip design, so that way you can easily grab on to it and makes for simple connecting and disconnecting. That's going to do it for today's look at the CURT LED 4-Way Flat Connector Tester for the vehicle end..

Customer Reviews

Curt LED 4-Way Flat Connector (Vehicle End) Tester - I26

Average Customer Rating:  4.9 out of 5 stars   (606 Customer Reviews)

- I26

Another great product from Etrailer.com Do yourself a favor, buy one of these to keep handy in your glovebox. They work great. 703362

- I26

I had placed an order from etrailer for a trailer wiring kit, as I'm going to be renting a uhaul trailer to move some stuff. The wiring kit looked fairly easy to install (based on a video on etrailer), but it then occurred to me that I wouldn't know if I installed it correctly until I picked up the rental trailer, and then it would be too late to do anything about it. So I looked at various testing tools and this looked like the easiest (and cheapest). It worked exactly as promised. (Turned out I installed the wiring kit correctly.) My only suggestion is that there should be a tag (or label, etc) on the tester indicating what light should light up for what function. I know the etrailer website shows which light is for which function (ie brakes, lights, turn signals), but it would make sense to enclose this info with the device. That said, this was easy to use and did exactly what it should. 141483

The wiring kit I bought continues to work just fine. Im also glad to have purchased the small wiring tester at the time - the first time I rented a trailer the lights werent working without the tester, I would have assumed the problem had to do with the installation of the new wiring, but this gave me the confidence to know the problem was with the rented trailer and I could insist they come and fix it which they did.Anyway, still very pleased with the purchase, and would continue to recommend it.
BJB - 07/20/2015


- I26

Works as expected 567965

- I26

After wiring up the harness this tester shows various lights when brakes, running lights and turn signals are activated. The only problem is that the lights are not labeled so you don't know what light circuit is being activated. With the harness I wired there was no way to wire it wrong ( just plug n play) so it should be correct. Have to wait until trailer is attached to be sure. 617603

The tester has one socket and three pins. The pin closest to the socket is the Running Lamp circuit, next is the Left TurnBrake Lamp circuit and last is the Right TurnBrake Lamp circuit.
-- Mike L - 04/06/2019


- I26
by: 11/19/2020


- I26
by: 11/15/2020


- I26

Very easy to install. 912311

- I26

Fit was good and works fine 909897

- I26
by: 11/08/2020

worked as expected 909582

- I26

Worked as advertised, very easy to inst all. 909855

- I26

Works great and helped not to have to second guess the installation of the wiring kit for my vehicle. Great accessory to have. 897989

- I26
by: 10/02/2020

Exactly what it was supposed to be and installed with ease. 902036

- I26


- I26

I Like the trailer hitch, wiring harness, wiring harness plug plug holder, and test plug! Also shout out to your associate Tanith S. Who was of immense help when I had a question on a back ordered part and wanted the main trailer hitch shipped to me. In the end everything came together which was great. Thanks to her! Will recommend your company to friends and associates! 892275

- I26
by: 09/24/2020

Easy to use tester. Better than using the wife and a multimeter. 892073

- I26
by: 09/23/2020

This is an essential tool to help ensure you have connected the wiring kit correctly. 887165

- I26

great tool to test your wiring work if you are alone. Just connected up, hung up in rear hatch area of SUV to view from mirror and tested brakes, turns and 4 ways. worth the investment. Better to check each days before hitting road than trooper giving you a ticket nowadays! 883553

- I26

Awesome way to test out your wiring without having an actual trailer. I was renting a tent trailer for the weekend so I needed a good way to test it out before picking up the trailer. 877487

- I26

This works very well when you are working by yourself. 876359

- I26

What a handy little tester. It basically tells you immediately that the wiring, battery, connections etc. on the vehicle end are working correctly. I used it to verify my initial installation of the T-One harness before hooking the harness to a trailer. The biggest help was on a fishing trip and one of the drivers was not able to get the lights on his trailer to work. We connected the Curt tester and quickly isolated the problem to the trailer side wiring. It saved a lot of time zeroing in on the problem area. I carry the tester on the same key ring as the lock for the bumper hitch. 876180

- I26
by: 09/05/2020

Worth every penny in headaches saved. 874781

- I26
by: 08/31/2020


- I26
by: 08/29/2020

Wish I had bought one of these years ag o! 871129

- I26
by: 08/28/2020

Worked well to confirm that my wiring was done correctly. I haven't borrowed a trailer yet, so needed the inexpensive tester to confirm. 870621

- I26
by: 08/28/2020


Show More Reviews

Ask the Experts about this Curt Wiring

  • Troubleshooting Vehicle-Side Trailer Connector Right Turn Signal Staying On
    If you are putting a test light like the Curt # I26 on your vehicle-side 4-Way then you may have installed your vehicle-side 4-Way incorrectly. Is your running light indicator blinking when you put your right turn signal on? If this is the case then you simply need to swap out the wires for your right hand and running lights (see attached photo). Another possibility is that you have a bad ground or your vehicle connector is full of corrosion. Check both of these while you are at it and...
    view full answer...
  • What are the Different Circuits on a 4-Way
    The jacketed circuit is the ground. The one right next to that one is the tail light circuit, next to that one is the left turn circuit. And then the last one on the end is the right turn circuit. Check out the picture I attached to see the circuits labeled. I attached an FAQ article on trailer wiring that you might find informative also.
    view full answer...
  • What are the Functions of the Lights for Trailer Wiring 4 Pole Flat LED Tester # I26
    From left to right the first light tests running lights, the middle light tests left turn and brake lights, and the last light tests right turn and brake lights. On a 4-Way flat vehicle connector, the one exposed pin is the ground, next to that is running lights, then left turn and brake, and the last pin is right turn and brake.
    view full answer...
  • Can Curt LED 4-Way Flat Connector # I26 be Left on Vehicle Indefinetely
    Leaving the Curt LED 4-Way Flat Connector # I26 plugged into a 4-way for an extended period of time would not be an issue at all. Since you used dielectric grease like the part # 11755 you wouldn't have to worry about corrosion either.
    view full answer...
  • Is There a Way to Trick Parktronic Sensors on a 2016 Mercedes-Benz Sprinter for a Bike Rack
    I am not sure if this will have enough draw but we have testers like the Curt LED Tester # I26 which puts a small load on a 4-Way Flat connector. This is used to make sure that your wiring is working correctly but it may be enough to trick your sensors. If you have a 7-Way then I recommend using the Tow Ready # 20142 as it will simulate a draw as well. Please note that both of these products are designed to be plugged in for short periods of time and haven't been tested for prolonged...
    view full answer...
  • Turn Signal Shows Hot all the Time with Plug-In Trailer Connector Tester
    If a 4-way trailer connector tester like part # I26 shows that the drivers side turn signal on the Curt T-Connector Vehicle Wiring Harness part # C56344 for your 2014 Jeep Compass is constantly hot then you would first want to remove the driver's side tail light assembly. Once this is done you would then need to remove the connector to the harness and inspect the pins making sure none of them are bent and or corroded. If they are then you will need to clean them up with some electrical...
    view full answer...
  • Fuse Blows on 4-Way Harness When Using Circuit Tester 2013 Jeep Compass
    It sounds like the 4-way tester you are using like part # I26 has a short somewhere which is in turn causing the 10 amp fuse on the Curt T-Connector Vehicle Wiring Harness part # C56344 for your 2013 Jeep Compass to blow. What I recommend doing is testing each circuit with a standard test light like part # 40376 to check for function. If all is good then you know the problem was in the 4-way tester you are using. All of the converter boxes used in Curt's wiring harnesses are tested...
    view full answer...
  • Why Would Circuits of the I26 Partially Glow When No Trailer Wiring Circuits are Activated
    It sounds like your trailer wiring setup is fine. The thing about LEDs (like what the # I26 has), is that they require such a tiny amount of amperage to partially illuminate that when they are used in trailer wiring situations they can partially glow like you described if there is any amperage at all bleeding out of the circuit. What I would do is connect the 4-way of your 2014 Ford Explorer up to a trailer and see if it functions properly. If it checks out then you would be good to go.
    view full answer...
  • Which Lights will Illuminate on the Tester # I26 When Brakes are Applied
    When your brake lights are pressed and you are using the # I26 as a tester the two pins opposite of the jacketed (ground) pin will illuminate. These are the left and right turn/brake light circuits.
    view full answer...
  • Comprehensive Vehicle Side Trailer Connector and Wiring Tester
    Most of the vehicle end trailer connectors we have will test for voltage on the circuits. If there was a short to ground then all of the lights would light up on the tester and you would know there is a problem. We do have a comprehensive trailer side tester, # 8010, which goes much further than any of the regular testers like # I26. But it is not designed for the vehicle side. For the vehicle side we have # HM50918 that can test multiple connector types on a vehicle (4-Flat, 6-Way round,...
    view full answer...
  • Recommended Trailer Wiring For 2020 Jeep Grand Cherokee Without Tow Package
    For your 2020 Jeep Grand Cherokee I recommend the Tekonsha T-One Vehicle Wiring Harness part # 118727. It's custom made for your Jeep and it gives you a 4 way flat trailer connector so you have all the lights to tow a trailer safely and legally. It gives you your tail light functions, turn signals, and brake lights. The wiring installs behind your tail lights and plugs inline between the factory connector and the light assembly. There is no cutting or splicing of the factory wires, however...
    view full answer...
  • Recommended Trailer Wiring Harness for 2020 Toyota RAV4 Hybrid
    The trailer wiring harness I recommend for your 2020 Toyota RAV4 Hybrid is the Tekonsha Kit part # 118801. It provides you with a 4 flat trailer connector, and has a plug in design; so it does not require any cutting or splicing. I also like the kit because the converter box in the kit has a reputation for being very reliable and has a higher amperage rating than similar wiring kits.The wiring kit installs behind the trim panels in the rear hatch on each side, where you can mount the converter...
    view full answer...
  • Is Dealer Activation Required for Trailer Wiring Harness # C55384 on 2015 Jeep Grand Cherokee
    When you install the Curt T-Connector Vehicle Wiring Harness for Factory Tow Package - 4-Pole Flat Trailer Connector # C55384, it may be necessary to see a local Jeep dealer to activate the tow package wiring circuit. Some vehicles have the active tow package wiring and others do not, so you will know as soon as it is installed if this is required or not. If you test the function using a tester like # I26, a circuit tester like # PTW2993, or connect it to a trailer, you will be able to...
    view full answer...
  • How to Determine if a 2017 Toyota Highlander has a Factory Tow Package
    To determine if a 2017 Toyota HIghlander has a factory towing harness, start by opening up the rear hatch. Then, lift up on the rear compartment panel and pull it out. Remove the two driver-side panels by pulling up on them. There, you may see a factory 4-pole. If you do, then you know for sure you have the factory towing harness. If you do not, you may still have one that didn't come with the 4-pole connector so continue to the next steps. Pull up on the tabs connecting the floor covering...
    view full answer...
  • Right Turn Signal Always Has Power When Testing 4-Way with Circuit Tester
    It sounds like you have a classic ground issue with the Curt T-Connector Vehicle Wiring Harness part # C56348. When testing the 4-Way with a tester like Curt LED 4-Way Flat Connector (Vehicle End) Tester part # I26 the right turn like should only light up when you activate the right turn function. If it is always illuminated like you mentioned, I recommend to make sure the ground wire of the harness is attached to a clean bare metal surface on the frame. If you don't have a proper ground...
    view full answer...
  • How to Wire LED Replacement Trailer Lights
    If you are looking at and LED Trailer Tail Light like part # STL8RB, then you will not need a converter to make it compatible with the 4-Way Wiring Harness on your truck. You will need to figure out the wiring on your trailer to make sure that you get all of the wiring done correctly. You can use a Circuit Tester # I26 for that purpose. All you have to do is hook up your new LED lights using the following information. Brown is for tail lights Green is for stop and turn White is...
    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...
  • Taillights and Turn Signals Working But No Brake Lights on Trailer
    Almost every trailer in the U.S. uses a 2-wire or combined wire tail light setup. This means that the turn signals and brake lights are on the same circuit and use the same bulb in the trailer tail light assembly. Because of this, virtually every trailer wiring adapter is designed to carry the turn signal and brake lights on the same pin circuit, so I would assume that this is the case for your 7 to 4 way adapter. It sounds like with working turn signals and taillights, that the problem...
    view full answer...
  • No Function on any Right Side Lights on Trailer Behind 2010 Subaru Forester
    I have found the best way to find a bug in an electrical system is by process of elimination. Eliminating possible sources will eventually lead to the right spot. First thing I would do, is check the 4-Way connector on your Subaru Forester. Using a circuit tester like part # 40376 or a 4-Way tester like part # F5CT or part # I26. The white wire is ground, the yellow wire is left turn and brake, the green wire is right turn and brake, and the brown wire is tail lights. Chances are, the...
    view full answer...
  • Trailer Hitch and Wiring Recommendation for 2014 Toyota RAV4
    For a trailer hitch for your 2014 Toyota RAV4 we have the Draw Tite hitch part # 75235 that you referenced which is a confirmed fit and would work well. This would have been what I would have recommended you since it has the best capacities and price so you are on the right track. Then for trailer wiring the Tekonsha kit part # 118578 that you referenced is the best choice as it is the most reliable option we offer too so it's the way to go. To test this 4-way we have the # I26 that...
    view full answer...
  • Recommendation on a Trailer Light Tester
    I found a solution for you. The Tow Ready 7-Way Trailer Vehicle Tester, # TR20117, will allow you to test the lighting functions on your vehicle's 7-way trailer connector. The plug connects and used LED lights that will display if you have a properly functioning 7-way or if there is an issue with the vehicles signal output at the connector. Also, if you are needing to test a 4-way flat connecter, I recommend the Curt LED 4-Way Tester, # I26.
    view full answer...
  • Troubleshooting Trailer Running/Parking Lights Not Working on Truck Wiring Harness
    From the sounds of it, you have a truck issue. Since you have used a multimeter like # BTMT15 as well as a lighted tester like # I26 or # TR20117, it does sound like you aren't getting that running light power. This is often a separate circuit in trucks, so you will want to check your owners manual for fuses or relays that state trailer running lights or parking lights. Fuses don't always look bad so you will want to use your meter to check for power on both sides of fuses and then...
    view full answer...
  • Vehicle Side 4-Way Trailer Connector Plug-in Circuit Tester Lights Light Up when Connected
    If the lights on a 4-Way trailer connector tester such as # I26 light up when connected that means that those circuits are receiving power. It doesn't take much power to light up these small LED lights so even residual current could set them off. This is typically more likely on aftermarket installed trailer wiring harnesses that have a connection to the battery to power the trailer lights. It could also indicate a short circuit if the lights stay on all the time. The likely cause is...
    view full answer...
  • Malfunction Turn Signal Light on Sunline Travel Trailer
    The first step would be to check the wiring from the malfunctioning light all the way up to the connector. Make sure all the connections are reasonably clean and secure, and check for frayed wires. If everything looks good from there, I would begin to look at the tow vehicle wiring. Check to make sure your connections are clean and secure. We have a few handy devices that could help you check all this. You could use a circuit tester like part # 40376 to check to see what connections...
    view full answer...
  • No Trailer Lights on a 2018 Honda Pilot with Tekonsha 7-Way Harness Part # 118760
    What type of tester are you using? If it is one like the Curt LED 4-Way Flat Connector part # I26 then that may be part of the problem as these are not foolproof and do not always work with all wiring harnesses. Therefore, I would check each of the pins with an actual circuit tester while the respective signals are active. These are much more accurate than the above testers. In regards to the T-One Vehicle Wiring Harness part # 118760 which is a fit for your 2018 Honda Pilot, there...
    view full answer...
  • Will Wiring Harness # 118534 Work with Power Lead Disconnected or Damaged?
    The T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # 118534 will not function without the power lead. It may function with a slightly damaged power lead, so I recommend using a tester like # I26 to test your wiring functions and simply visually inspect your power wire to your battery.
    view full answer...
  • Testing the Hopkins 4-Way Connector Not Showing Power on a 2009 Chevrolet Equinox
    You can test the Hopkins # HM11141265 by using a circuit tester like part # I26 while you have a helper activate the various light functions on your 2009 Chevrolet Equinox to make sure that the correct signals are coming through. If they aren't then you have some bad wiring on your Equinox (granted you installed the fuses and relays and they are okay). If you do get signals then you have a wiring issue on your trailer. This can be traced back to a faulty ground or damaged wiring. Make...
    view full answer...

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Info for this part was:

Test Fit:
Joe V
Video by:
Andrew K
Expert Research:
Jameson C
Installed by:
Cole B
Video Edited:
Chris R
Updated by:
Kristina F
Updated by:
Isabelle B

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