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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 # C73NR
Our Price: $17.65
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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. Color-coded LEDs make it easy to distinguish each signal. 1-800-940-8924 to order CURT electrical tools part number C73NR 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 (14)
  • Q & A (0)
  • Videos (2)
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CURT Electrical Tools - C73NR

  • 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. Color-coded LEDs make it easy to distinguish each signal.


  • 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
    • Color-coded LEDs make it easy to distinguish each vehicle signal
  • Integraded resistors are compatible with Smart Tow

58272 Curt 7-Way RV Blade Connector Tester

Installation Details C73NR Installation instructions

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 Review of CURT Electrical Tools - 7-Way LED Circuit Tester - C73NR

Hi there. I'm Michael with Today we're gonna take a quick look at this Curt 7-Way to RV Socket LED Circuit Tester. Now this 7-way connector tester is going to plug into your vehicle's wiring harness to confirm your lights are functioning properly. You can see we do have a color-coded and labeled set of LEDs here that are going to make it very easy to distinguish your vehicle's signals. So, if we work from the bottom here, you can see we've got our TM for our tail lights.

We've got our LT for our left turn signal and our RT for our right turn signal. Those will both light up for our brakes, so we can check our brakes. We've got the BU for our backup, BK for our electric brakes, and then our 12V for our auxiliary power. So this will be very easy to operate. Just plug it right in, apply your turn signals, brakes, electric brakes, that sort of thing.

It will light up to indicate that it's functioning properly. We can loosen this screw on the backside that will allow us to twist that LED head so that we can get that lined up in whatever orientation is gonna be easiest for us to view as we are testing those out. So we'll just take a little bit of backing out of that screw there, and then we can twist the head to whichever orientation is gonna be easiest for us to see, and then tighten it back down so it always be able to make sure that we have a very easy time just to plug this in and then operate those signals, make sure that they're working properly. So that completes our look for today. Again, I'm Michael with

Thanks for watching.

Customer Reviews

Curt 7-Way to RV Socket LED Circuit Tester - Vehicle End - C73NR

Average Customer Rating:  4.9 out of 5 stars   (14 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. Color-coded LEDs make it easy to distinguish each signal.


I had an electrical issue with my 5th wheel connector and needed to troubleshoot it. I immediately thought of etrailer and had the tool delivered to my campsite. Problem solved.


After struggling with erratic trailer lights checking ground connection, light bulbs and possible shorts, I finally decided to check my truck connection. The curt 7-way tester revealed my trailer circuit breaker to the running lights was blown. Replaced it and problem solved. Took less than 5 minutes with the curt 7-way tester to reveal my problem. If I had already purchased this tester before checking out my trailer it would have saved me the 2 hours I spent diagnosing the trailer first. Outstanding product and a big thank you to etrailer for carrying this product. Plus the video provided by etrailer on their website does a great job explaining how to use the device.


Just what I needed to figure out why our lights weren't functioning properly! Worked perfectly.


The product arrived on time. Work's like it should.


works great


Worked perfectly right out of the box.










See what our Experts say about this CURT Electrical Tools

  • Troubleshooting a Tekonsha Prodigy RF Brake Controller that Wont Pair
    Are you getting any kind of code on the handheld system that comes with the (discontinued) Prodigy RF 90250? One thing that might be wrong is that vehicles with certain late model European tow packages may require the use of a tester like part # C73NR or another truck or SUV to pair the receiver and transmitter. Try this out and let me know if it fixes your problem. If it doesn't, let me know what the year/make/model of your tow vehicle is as well as what wiring connector you have on your...
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  • 7-Way Tester Recommendation for 2016 Chevy Silverado 1500
    The 7-way tester part # C73NR would work on your 2016 Chevy Silverado 1500 for all circuits unless you have an integrated brake controller. That's pretty much the only circuit we have found that doesn't like to work with this tester on the newer Chevy trucks.
    view full answer...
  • 7-Way Tester Recommendation for a Land Rover with 7-Way and P3 Brake Controller
    Yes, we do offer a 7-way tester that will allow you to plug into the 7-way at the rear of your Land Rover to test all of the functions. For that you would want the part # C73NR.
    view full answer...
  • How To Test Factory Brake Controller Function on 2019 Ford F-150
    The only true way to test the brake controller in your 2019 Ford F150 is by connecting it to a trailer with brakes. You could use the brake controller's manual override with the tester plugged in to make sure that the signal was being transmitted to the pin on the 7 way, but you're really going to want to test everything out with a trailer installed to be 100% sure it's functioning correctly and providing the correct braking when you adjust the gain and such.
    view full answer...
  • Flashing Trailer Lights with a 2008 Mercedes GL450 with Factory Tow Package
    It sounds as if you have the trailer ruled out as the problem. I would recommend you check the ground connection on the trailer, to make sure it is connected securely to clean metal, so you eliminate that as a potential problem. I would then look at the connector on the vehicle. Try using a tester, part # C73NR to check if all circuits are functioning. If you find a problem at the connector, since the tow package is factory, not aftermarket, I would recommend you check with your Mercedes dealer.
    view full answer...
  • Troubleshooting Trailer Lights and Connectors On 2002 GMC Yukon
    The first place I would check is the fuse box. The trailer turn signals and trailer running lights are all on separate circuits. The fuse box under the hood is where they are located, and they are in the front closest to the stud on the right side. They're labeled TRL R TRN and TRL L TRN. You can find the diagrams for the fuse boxes on page 6-70 of your owners manual. If the fuses are blown, they will need to be replaced and you can recheck the functions at the connector on the back of...
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  • Replacement 7-Way and Circuit Tester Recommendation for a 2005 Ford F-350
    For a replacement 7-way that has been confirmed to fit your 2005 Ford F-350 and has the added benefit of having a 4-way attached to it as well you would want the part # 74682. It will plug into the same round connector that your current connector is plugged into. For a tester for this 7-way you would want the part # C73NR. This will plug into the 7-way and will tell you which circuits are working as you apply them.
    view full answer...
  • Troubleshooting Left Turn Signal Staying Hot on a 2013 GMC 3500HD Towing a Trailer
    If you used a 7-way circuit tester like our 7 Way Trailer Connector Vehicle Tester # C73NR and the LT circuit stayed lit that would indicate that there is voltage on this circuit at all times which means something is shorting out onto this circuit. Due to the fact that it is hot all the time it would seem that it is the 12 volt power circuit that is shorting to the left turn/brake circuit. I suspect you have a 7-way round connector since on these style connector the left turn and 12 volt...
    view full answer...
  • Trouble Shooting Inoperable Electric Brakes on a 10K Trailer
    Since you have fresh parts in the hubs and provided they are installed properly, I suspect there is a problem somewhere in the wiring or with the brake controller installation and set up. You will need to check the whole system, step by step, to find out where the problem is. If you have used your truck successfully with other trailer brake equipped trailers, then the brake controller and vehicle wiring should be fine and you can skip the first 2 steps. If you tried it on different vehicles...
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  • 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...
  • Which Port Should a Trailer Jack be Wired to on a 7 Way Plug?
    The center port on a factory plug will typically be reverse lights on a 2019 Ford F-150. To power the jack on your trailer, you should be tapping into the 12 volt power port on the 7 Way. This will be the port in the 2 o'clock position on the 7 Way on the vehicle. If your jack is wired to the center function, you will need to rewire it and you should be good to go.
    view full answer...
  • No Power On 12 Volt Circuit on 7-Way Trailer Connector on a 2006 GMC Sierra 2500HD
    On some GM trucks, even those with factory tow package, the wiring is not always complete. You may need to manually run a wire from the front of the truck to the back of the 7-Way. I have included a link to the right that should help. It talks about the under the hood connections that might need to be made when installing a brake controller but also mentions the 12 volt power wire. Presumably, if the wire is attached directly the positive terminal, it would have power all the time. But...
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  • Could Center Pin of Trailer Wiring 7-Way be 12 Volt Accessory Circuit
    You basically already did verify that the center post of your 7-way is the 12 volt accessory circuit. Normally the center post is the reverse light circuit and the 12 volt pin is the 1:00 pin position. If your center pin is hot all the time then it would be the 12 volt accy circuit.
    view full answer...
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  • How To Test 12 Volt Signal On Ford Truck Trailer Connector Without Trailer Connector
    The 7 Way Trailer Connector Vehicle Tester part # C73NR should work well to test the trailer battery charge line on Ford trucks with the Smart Tow Package because as you mentioned the trailer battery charge line is not active until a trailer is connected and you depress the brake pedal. The 7 Way Trailer Connector Vehicle Tester part # C73NR would then act as if a trailer was connected. That said, if you are having issues with the trailer battery charge line circuit then make sure you have...
    view full answer...
  • 2006 Ford F350 With OEM Brake Controller Not Reading Trailer
    When using the wiring diagrams you speak of, it is important to remember that wire colors can vary, and it is best to wire by function rather than wire color. The easiest way to determine which wiring circuit preforms which function is to use a car battery, ground the white wire from the trailer connector lead to the negative battery terminal, and apply 12 volts to each of the remaining circuits in order to determine their function. By going this route, you can be sure that the connector...
    view full answer...
  • 7-Way Trailer Wiring Tester Recommendation
    If you were looking for a 7-way tester that's a standalone tester and does not need to wire to a trailer you'd want the 7-Way tester part # C73NR which plugs into a 7-way socket and will let you know which circuits are active. See attached review video.
    view full answer...
  • How to Tell if the Brakes are Working on a Horse Trailer
    The easiest way to tell if the brakes are working on the trailer would be engage the manual override and have a friend sit outside the vehicle and watch the wheels on the trailer. If they begin to drag when you let off the brake pedal (slowly) on the tow vehicle then you know they are working. You can also test the brake output wire just behind each assembly with a circuit tester to ensure they are receiving power. If the brakes are not engaging then please let me know and I would be...
    view full answer...
  • Should Trailer Wiring Have the Running Light Circuit Always Activated
    The only time the running light circuit of trailer wiring should be on is when the headlights or running lights of the vehicle are on. You might have a shorted trailer wiring converter box or a bad relay if the trailer wiring is factory. I attached a help article on troubleshooting trailer wiring installs for you to check out as well.
    view full answer...
  • Trailer Tester To Test Trailer Wiring Without Plugging Into Tow Vehicle
    The Hopkins Tow Doctor Trailer End Test Unit # HM50928 will allow you to test a trailer with 4-way flat, 6-pin round, or 7-way blade connectors. The test will connect to a 12-volt battery and allow you to test all your lights as well as trailer brake operation and the charge line connection.
    view full answer...
  • Troubleshooting 2019 Ford F-150 Having No Power To 7-way Connector After Replacing Fuse
    I would be happy to help. Since you replaced the Trailer Tow Parks Lamps Fuse 53 in your 2019 Ford F-150 and are now not getting any power to your 7-way connector, I recommend checking fuse 43 as it is for the trailer tow park lamps module. If that doesn't fix the issue go ahead and check fuse 103 and 74 as that is the two fuses for the other lighting functions. If you have still have no power to any of the pins of your 7-way connector, and none of the fuses in question are blown, I...
    view full answer...
  • Where Does Power for 12V Pin on &-way Come From on a 2015 Ram 2500
    The 12V Power pin, in the 1 o'clock position, on your 7-Way should be receiving constant power from the battery in your 2015 Ram 2500. Some pickups will cease to send power to that pin if the ignition is off so if you are lacking power then that may be the reason. You also may need to replace a fuse or relay. When I looked up your online owner's manual the only thing I could find that may be related to this circuit is the 30 amp fuse in the F30 position in your power distribution center...
    view full answer...
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  • How to Test a 7-Way Trailer Connector on a Tow Vehicle
    Yes, in order to test the trailer connector on your tow vehicle you can use a standard circuit tester or a plug in tester like the 7 Way Trailer Connector Vehicle Tester part # C73NR. This is going to make testing the wiring on your tow vehicle simple. All you need to do is plug the tester into the trailer connector and then activate the signal while checking for the red light on the tester. If the red light appears you know that circuit is active but if not then you know there is an issue....
    view full answer...
  • Trailer Lights Stay On After Tow Vehicle is Shut Off
    Somehow you're getting bleed-over from the 12-volt accessory circuit to the lights on the trailer. This most frequently occurs due to corrosion in the trailer connector on the vehicle or on the trailer. Since you've recently replaced these, then we'll look at the junction box. What's likely happened is that the tabs on the ring terminals are contacting each other. When tightening the ring terminals down on the lugs in the junction box, be sure that none of the ring terminals are touching...
    view full answer...
  • Activating 12 Volt Power Circuit of 7-Way at Rear of 2016 Chevy 2500HD
    There's a connection you still need to make under the hood of your 2016 Chevy Silverado 2500 to complete the 12 volt power circuit of the 7-way at the rear of your truck. If you check out the picture I attached you'll see what connection I am referring to.
    view full answer...
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Info for this part was:

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