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Curt 7-Way to RV Socket LED Circuit Tester - Vehicle End

Curt 7-Way to RV Socket LED Circuit Tester - Vehicle End

Item # C66NR
Our Price: $13.94
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Shipping Weight: 0.22 lbs
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This circuit tester plugs into the 7-way connector on your vehicle. LED lights indicate which functions (brake, turn, tail, stop, reverse, electric brakes, and 12V) are properly working. 1-800-940-8924 to order CURT electrical tools part number C66NR or order online at Free expert support on all CURT products. Great prices and Fastest Shipping for Curt 7-Way to RV Socket LED Circuit Tester - Vehicle End. Electrical Tools reviews from real customers.
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  • Reviews (16)
  • Q & A (0)
  • Videos (2)
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CURT Electrical Tools - C66NR

  • Testers
  • Circuit Tester
  • Tow Function Tester
  • CURT

This circuit tester plugs into the 7-way connector on your vehicle. LED lights indicate which functions (brake, turn, tail, stop, reverse, electric brakes, and 12V) are properly working.


  • 7-Way connector tester plugs into your vehicle's wiring harness to confirm your lights are functioning
    • Tests tail lights, brake lights, turn signals, reverse lights, electric brakes, and auxiliary power
  • Labeled LED lights indicate which functions are working properly

58270 Curt 7-Way RV Blade Connector Tester

Video of Curt 7-Way to RV Socket LED Circuit Tester - Vehicle End

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

Video Transcript for Curt 7-Way to RV Socket LED Circuit Tester Review

Hey, everybody, Ryan here at etrailer. Today we're gonna be checking out the CURT seven-way tester and this will allow you to check the lighting functions on your vehicle's seven-way trailer connector. This is gonna be a bladed style and work with just about all the different types of trucks and motor homes and RVs that have this style of plug. The way this is gonna work is super simple and it's gonna check all the different types of functions. So we'll have our brake controller if your vehicle's equipped with one, the backup or reverse lights, you have your right turn signal, your taillights, your left turn signal, your 12 volt auxiliary power, and then how trailer wiring is set up, whenever you hit your brakes, you should get the right turn and left turn to illuminate as well, 'cause the stop and turn's kind of integrated in one, if that makes sense. But really not a whole lot to it.

You'll come up to your vehicle, just plug that right into the 7-Way, and we can check our functions. So right now our 12 volt auxiliary power is illuminated. We'll have to hop in the truck and go through the signals to make sure that they're all working properly. Go ahead and try out our left turn signal, our right turn signal, we'll turn on our taillights. We're gonna hit our brake pedal.

And if you had a brake controller at this time you could do the apply power to it, make sure you're getting that signal back, and the test reverts, I'll have to go ahead and start up the vehicle here to get that signal sent back. (engine ignites) After running through the signals we verified everything is good to go on our vehicle side. And so having a tool like this is something good to have. It's gonna help you isolate a potential wiring problem. 'Cause it never fails, it always seems like you go to hook up to your trailer and one of the lights aren't working, or whatever the case may be.

And where do you go from there Is it the vehicle side Is it the trailer side So this is gonna help you determine that. So if you run into that issue, you can hook this up to your vehicle, run through the signals. If they're all working, you need to focus your energy on the trailer side. You might have a bad ground or a bad connection, burned out bulb or something along those lines. However, if you go to test out your vehicle and it's not working back here, chances are pretty good you need to focus your energy on the vehicle side, whether you have a blown fuse, something like that.

This'll help get you going in the right direction to make sure all your lights are gonna work and keep you safe and legal. Just to kind of do a quick comparison with the CURT one here, here we have a Pollak, and they're pretty much the same thing. I mean they look a little bit different. The color of the LEDs are a little bit different but it's not really a huge deal. The one thing that's somewhat notable is the CURT one's a little bit longer and so here we'll plug this in, give you an idea. So the CURT one, this part, the lights where you see extend well past our cap here. The Pollak one's a little bit shorter and so somewhat covered up by the cap. Again, not really a huge deal, but if that we're to bother you, if you we're doing it by yourself, it might be a little more kind of a pain to see what's going on, but not a huge deal. Something worth noting that I've experienced with both of these in the past, and this holds true for a lot of the testers with exception of the more high dollar ones, is being able to test that brake controller. So I've noticed, not every scenario, but sometimes if you get more of a late model truck, especially the ones that have the factory built-in trailer brake controllers, a lot of times you're not gonna be able to receive or test that brake controller output. The trucks are just too smart. They realize that this isn't a trailer with brakes and won't send that signal back. So if that happens to you, don't be totally surprised. On a lot of some older vehicles or vehicles that have an aftermarket type brake controller, a lot of those usually do work, but again, it's hit and miss. So just figured I'd throw that out there, that way you can at least expect that to potentially happen. So when it comes down to it this is a great little tool to have. it's small enough you can throw it in your glove box and the next time you encounter some lighting issues when you're going to hook up to your trailer, can break this out and help you get it all sorted and figure out what's going on. But I think that'll about do it for our look-at of the CURT 7-Way tester.

Customer Satisfaction Score:

Customer Reviews

Curt 7-Way to RV Socket LED Circuit Tester - Vehicle End - C66NR

Average Customer Rating:  4.8 out of 5 stars   (16 Customer Reviews)

This circuit tester plugs into the 7-way connector on your vehicle. LED lights indicate which functions (brake, turn, tail, stop, reverse, electric brakes, and 12V) are properly working.


Much easier than the test light.


took a long time to get here but i like it


Does exactly what is supposed to do


Worked good and seems very well made (solid). I like the labels on each LED.


Looks good fast Shipping


Etrailer Expert

Jenny N.


I can wish on a falling star however it would be to help you with this tester. If you can give me more details I would be happy to assist.












See what our Experts say about this CURT Electrical Tools

  • Will 7-Way Socket Circuit Tester if Ground Circuit Isn't Active
    Correct. If the trailer wiring ground isn't good then the rest of the wiring won't function either and show up on a circuit tester like the Curt # C66NR that you referenced.
    view full answer...
  • Why Does New GM Truck Trailer Wiring Not Work Great with Circuit Tester
    New GM trucks don't have consistent 12 volts on their trailer wiring circuits. While this tends to not be a problem for trailer lighting it does not always work great with more sophisticated circuits like your tester. This is a big issue for camera systems that use the running light circuit for their power supply.
    view full answer...
  • Troubleshooting Curt T-Connector 7-Way Circuits With No Power On a 2022 Ford Ranger XLT
    It sounds like your 2022 Ford Ranger XLT may be missing or have damaged fuses/relays for the trailer functions. You will want to check your fuse panels for all the necessary trailer related fuses and relays. It is a little worry some the only light working on your Tester # C66NR is the BK. BK identifies the trailer brakes. If you have installed a trailer brake controller this is going to be normal but if you do not have a brake controller you installed then you will need to determine why...
    view full answer...
  • Recommended 7-Way Tester that is Compatible w/ Ram Factory Brake Controllers
    I haven't heard of the Curt 7-way tester not working with OEM brake controllers. There was a Tekonsha tester that had problems with Dodge and GM trucks so it is possible. We have been able to confirm that the Pollak 7-Way to RV Socket LED Circuit Tester item # PK12741 is compatible with Ram factory controllers. The Curt 7-Way to RV Socket LED Circuit Tester item # C73NR and item # C66NR are the same testers they're just a different color. There is one thing to note about the use of...
    view full answer...
  • 7-Way Tester that Tests Function of 7-way on Trailer
    We do have 7-way trailer wiring testers like with the Hopkins part # HM50918 which you'd plug your trailer 7-way into and it would put voltage on all of the pins to verify they are all working. This is a lot more involved than the opposite end tester which is why you'll notice it's a bit more expensive.
    view full answer...
  • Is Curt 7-Way Tester Detected as Trailer
    We've heard of this from Ram owners as well, so the Curt 7-Way to RV Socket LED Circuit Tester - Vehicle End # C66NR won't be detected as a trailer being connected on your Ford. Our customers have success with the Pollak 7-Way to RV Socket LED Circuit Tester - Vehicle End # PK12741 so I recommend going that route.
    view full answer...
  • Troubleshooting a New 7-Way Trailer Connector That Is Causing Lights to Stay On After Truck Is Off
    This sounds like there is either short somewhere in the circuit or your ground is weak. You'll want to make sure that the ground is clean from corrosion and that the ground is connected securely. You're going to want to also inspect all of your wiring once again and make sure there are no breaks or damaged wires. Even though you mention that it is a fairly recent change, it still is worth a once over to be sure. If you've done all that and you're still having issues feel free to come...
    view full answer...

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Info for this part was:

Employee Lindsey S
Edited by:
Lindsey S
Employee Jeff D
Installed by:
Jeff D
Employee Ryan G
Installed by:
Ryan G
Employee Jameson C
Expert Research:
Jameson C
Employee Joshua S
Video by:
Joshua S
Employee Dustin K
Video Edited:
Dustin K
Employee Sabrina W
Written by:
Sabrina W

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