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7 Way Trailer Connector Vehicle Tester

7 Way Trailer Connector Vehicle Tester

Item # TR20117
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A circuit tester that plugs into the 7-way trailer connector on the vehicle and emulates a trailer. The lights let you know what functions (brake, turn, tail, stop, reverse and 12V) are working properly and what functions are not. 1-636-306-4830 to order Tow Ready electrical tools part number TR20117 or order online at Free expert support on all Tow Ready products. Guaranteed Lowest Price and Fastest Shipping for 7 Way Trailer Connector Vehicle Tester. Electrical Tools reviews from real customers.
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  • Reviews (221)
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Tow Ready Electrical Tools - TR20117

  • Testers
  • Tow Function Tester
  • Tow Ready
  • Black

A circuit tester that plugs into the 7-way trailer connector on the vehicle and emulates a trailer. The lights let you know what functions (brake, turn, tail, stop, reverse and 12V) are working properly and what functions are not.


  • 7-way circuit tester
  • 12V power
  • Function Codes:
    • BU: back up or reverse circuit center pole
    • RT: right turn/brake
    • TM: taillights
    • LT: left turn/brake
    • BK: Brake controller output
    • 12V: 12-volt power feed

Note: Designed for use with Tekonsha and Draw-Tite aftermarket brake controllers and Ford OEM brake controllers. May or May not work with other manufacturers brake controllers.

20117 Tow Ready 7 Way Trailer Connector Vehicle Tester

Replaces 18179

Installation Details TR20117 Installation instructions

Video of 7 Way Trailer Connector Vehicle Tester

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

Video Transcript for Tow Ready 7 Way Trailer Connector Vehicle Tester Review

Today we're going to show you the 7-way trailer connector vehicle tester, part number TR20117 from Tow Ready. All right, this is a handy device to keep with your vehicle. You can use this to test your vehicle any time. For instance, you have a problem with your trailer, you're not too sure where to start. Go ahead and use this tool in your 7-pole connector in your truck to verify your truck is working fine, then you know it's on the trailer side. Now the indicators are going to be these LEDs right here.

They have their own markings. TM for the running light circuit or trailer marker lights. LT for left turn, twelve volt power supply, so something in your trailer may require twelve volts like the interior lights or something like that. BK for the output from your brake controller. BU for your backup lights, reverse lights, and RT for your right turn signal.

And bye the way, with the brake controller this test was actually designed for use with Draw-Tite or Tekonsha brake controllers, and also the Ford OEM brake controller as well. This may or may not work with other brands of brake controllers out there. Let's go ahead and plug it into our truck here and show how it works. Just like any other 7-pole connector, you just push it in place. Make sure it's fully installed. You can see where I already have a couple of lights showing up.

One's going to be four a twelve volt power supply, and one's going to be for a brake controller outlet. All right, in this case our brake controller sends out a small trace current to look for a completed circuit, so that's why we have it lit up already and we're not even using our controller. That's perfectly normal. Okay Let's go ahead and try the running light circuit next. All right, that's our indication for the running lights.

Let's try our left turn signal. Okay. Now let's try our right turn signal. Okay. Let's look for our brake signal, which would be indication on our left turn and right turn signals. Okay. All right, and now we'll go ahead and try our back up lights, which we will put the vehicle in reverse. That will finish it for part number TR20117, the 7-way trailer connector vehicle tester from Tow Ready.

Customer Reviews

7 Way Trailer Connector Vehicle Tester - TR20117

Average Customer Rating:  4.8 out of 5 stars   (221 Customer Reviews)

A circuit tester that plugs into the 7-way trailer connector on the vehicle and emulates a trailer. The lights let you know what functions (brake, turn, tail, stop, reverse and 12V) are working properly and what functions are not.


I bought this to be able to do a quick test of the signals coming from the car to aid in diagnosing problems. It identified a problem with brake lights not operating due to a software problem in the car.


I have a 2019 F150 which has a 7-pin and 4-pin receptacles arranged vertically so that when you plug this tester in the lights face down and you need a mirror to see them. HOWEVER, I was able to loosen the "cable clamp" set screw and gently rotate the end so now I can see the lights. According to Tow Ready, the internal wires are not long enough to do this so just be gentle and stop when you feel the slight resistance. Might not get a full 180 degree rotation but you get enough to see the lights easily!


Works perfectly and it's great have the comfort of knowing that the tow vehicle's electrical is working properly.


It was perfect to confirm my wiring setup. One minor issue is that the indicator panel was pointed toward the ground when plugged into my truck receptacle, making it next to impossible to read. Rather than return the unit, I loosened a screw and gingerly reoriented the indicator panel for best viewing. The unit works great and fulfills my needs.


The product wasn’t very useful for my application. I have an OME installed trailer kit which has an isolation box between the vehicle and the trailer connector. I could tell the turn signals worked and that the electric break controller was working but everything else caused the LEDs to glow with what looks like high impedance semiconductor leakage regardless of whether the light was off or on. There just not enough load in the tester to bleed off stray voltage. I went old school with two clip leads, a 12 v bulb and an ice pick to verify that the vehicle was functioning properly. I have no confidence in what the tester indicates when the LED glow and whether the trailer connector is working or not. This will probable work if you only have copper between your vehicle lights and your trailer connector.


This is a must if you are pulling trailers using multiple trucks for towing. it will save you hours of work figueing out problems.

Still works great
James R - 05/31/2020


This 7 Way Trailer Connector Tester does Exactly what I was hoping it would do. It clearly indicates which electrical function is working on the Vehicle. I rated this "Very Good" rather than "Excellent" for ONLY one reason. When looking at the indicator lights on the tester they DO show which function is operating. What "might" be a little confusing to some is the fact that the indicator lights to not match exactly to the location of each tab inside the plug mounted on the Vehicle. Had the indicator lights on this tester match each location inside the plug I would absolutely have given this an "Excellent" rating. I still feel this is a Very Good tool for testing the wiring to insure each function is working properly.


The product plugs in and lights up but the only fault I found is it will not check battery and brake function as should because of the Ford computer. The plug does not pull enough amps for the computer to pick up a trailer connection made. So all that lights up is the other lights such as tail, turn and marker lights. In the description it said it would work with the Ford factory (in dash) controller

Ford trucks of recent manufacture feature what Ford refers to as a smart trailer connector. The connector wont output 12-volt accessory or brake power to the trailer connector unless the electrical load from a trailer is detected.
-- Etrailer Expert Mike L - 01/10/2019


The tester makes it very easy to eliminate the tow vehicle as a source for any trailer light or brake problems. Worth the cost for ease of testing.


works fine


Fits perfectly into 7-pin and works great, verifying everything is working properly!


This very simple device makes it easy to verify if your vehicle wiring is doing what it is supposed to be doing with the trailer lights and electrical needs. If your vehicle isn't providing the right power, stop looking at the trailer wiring! This narrows down the search for that loose wire or fuse instantly. Verifies everything is okay instantly. It's simples, rugged, and easy to stow in the vehicle to help you or others with trailer wiring issues. Highly recommend this to others.


I am very happy with the 7 way tester, TR20117, and used it to determine that the add on extender the RV dealer instakked on my 4Runner they hitch was changed had a loose a connection. I was able to use the tester to easily determine that the missing running lights were due to the 7way connector extension. I disconnected the extender and was able to stretch the original line to the new hitch. All is working well.
I originally ordered a Brake line and connector for my trailer and that was a UPS fiasco of no fault of I live in the country and gave them my street address thinking UPS would deliver there. They dropped the package at the wrong post office and of course my address was not deliverable. After giving my PO box number as the delivery address UPS again dropped it at the Post office to get it to me. This appears to be a new delivery method for those of us with PO boxes. Needless to say I ordered the second part because etrailer did so well in locating the problem change with UPS delivery.


I wish that I had this product many times over the years of pulling trailers with different vehicles. It makes it so easy to verify that all light connections are properly wired and working correctly. I have several vehicles and I can check each one in a couple of minutes and verify proper wiring. The test lights are bright and can be seen even in sunlight. I would recommend this product to anyone that pulls a trailer.


With this product I was able to narrow down my electrical problem to my truck and not the trailer, and by knowing that the problem was the truck I was able to narrow down the problem down to a 1 foot long piece of wire behind the tail lights but before the outlet. I did all this by simply looking at the tester and following the wires with my eyes. This tester saved me several hours of time, money in parts I didn't need and not to mention the immeasurable frustration caused by trying to find electrical wiring problems.


The 7 way trailer connector tester works great. No guessing about the wiring because you just plug it in and the lights will light up showing the connection corresponding with the light on the connector tester. Saves a lot of time.


Purcased this product in conjunction with a a 5th wheel/ gooseneck trailer wiring harness. Once the wiring harnesses was installed this tester made it easy to verify that all light functions were working properly without having to actually hook up to a trailer. 5 stars!


I don't trailer very often and this is a handy tool to verify vehicle side plug is working after prolonged periods of non-use. Most issues I find are on the trailer side, i.e., broken lights and wires.


The product was delivered on time and was exactly as advertised. Plug and Play into the existing wiring harness. Using the instructional videos on the website, the harness was neatly installed.


This 7 way vehicle connection tester works great. I'm able to trace any poor or bad connections associated with my truck's trailer harness quickly. Low cost and quality design makes it a great tool to leave in the trucks toolbox in case I have future connection issues.


I received my 7 way tester fast , and it was packaged well.
it came in handy to test my trucks plug to find out it wasn`t getting any power.
when I found out what the problem was it was real easy to look at the lights on the tester to see they were all working rather than hooking the trailer up and keep running back to the trailer to check if they were working.


This item was extremely helpful in my recent purchase of a tow vehicle. I had been looking at used trucks and brought this to determine if the wiring in the tow package was in working order - come to find out the 12v light wasn't coming on so I was able to tell the dealership I'd buy the truck if they'd be sure to fix it. Turns out it was only a fuse so an easy fix. I believe this will come in handy from time to time if I find anything not working on my trailer (will know if it's on the truck end or on the trailer). Thanks eTrailer for a FAST delivery and great product.


I have only used my tester twice, it worked great! My connector on my truck was hooked up right. My bosses was not. It was nice to be able to just plug it in w/out having to hook up a trailer. It is a great compliment to anyones toolbox.


The product is good with the STANDERD trailer hook up, But it does NOT work on my 2013 chevrolet 2500 inergrated braking towing controller ( IBTC ) When you hook the tester to the plug and apply the trailer brakes all you see is one Blink on the tester and then it goes back out.
Now I took my New 2013 truck to the dealer and they checked the braking system and found Nothing wrong and said it was OK .
Please test this on the 2013 chevrolet 2500 ( IBTC) and you will see what I mean and please if there is anything that I have done wrong please contact me because this tester does NOT work on my NEW truck .....Please respond !


This product (TR20117) helps with verifying that vehicle outputs are correct. If the vehicle is good you are ready to troubleshoot the trailer. I use a small 12 volt battery and two leads with alligator clips to test each function on the trailer. Etrailer has excellent wiring diagrams and diagnostic information - in addition to excellent pricing, great service and delivery.

Hope this helps.... Pat

Show More Reviews

See what our Experts say about this Tow Ready Electrical Tools

  • Will Tow Ready 7 Way Connector Vehicle Tester # TR20117 Test If a Brake Controller is Working
    The Tow Ready 7 Way Trailer Connector Vehicle Tester, part # TR20117, will test the 7-Way connector on your 2008 Ford Super Duty to make sure all the functions are working and the terminals are wired properly. It will tell you if you have 12 volt power and brake lights at the 7-Way which is needed for a brake controller. It does not test to tell if your brake controller is working or not. You will need to test your brake controller separately. I am including a link to a video that will...
    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...
  • No 12 Volt Power on 7-Way on a 2012 GMC Sierra Denali
    Most likely you need to make some connections under the hood of your truck to make the 7-Way fully functional. Under the hood, driver side, near the windshield you will find the power distribution box, There should be wires attached to the 2 studs on the forward most studs. If there are not you will need to locate them and attach them. The battery charge wire should be located under the master cylinder/brake booster assembly. Attach it to the smaller stud on the front of the power distribution...
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  • Tow Package Trailer Wiring Fuse and Relay Locations for a 2008 Ford F-350 Diesel
    There is a relay for the 12 volt circuit on the 7-Way in your 2008 Ford F-350. There are 2 fuses and 1 relay related to this circuit. The relay is in location 56 in the power distribution box under the hood. As you said there is one fuse in the cab in location 33 and one in the power distribution box in location 44. The following are the other relay/fuse locations for the tow packaging wiring on your truck: Under the hood Location 5 - fuse for brake controller Locations 20 and 21 - relays...
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  • Troubleshooting Trailer Brakes Locking Up When Lights are On and no 12 Volt Circuit Voltage
    It sounds like somehow the running light circuit got wired to the brake output circuit of the 7-way at the rear of your vehicle, and that is why when the lights are on the brakes lock up. I would check the wiring of the brake output circuit of your 7-way, I would be willing to bet there are two wires run to it and one of them is the running light circuit that should be run to the correct terminal of your 7-way. Check out the FAQ article I attached on trailer wiring.
    view full answer...
  • When Should Brake Output Circuit Light on Circuit Tester part # TR20117 Activate
    Brake controllers are designed to only put voltage on the brake output circuit when they are activated by either a brake pedal or the manual override lever of the controller. If your controller wasn't being activated the circuit on the # TR20117 won't show any voltage. Try having a friend apply the manual override of the controller while you watch the tester. You should see the light on the tester come on at that point.
    view full answer...
  • 7-Way Tester Recommendation for 2016 Chevy Silverado 1500
    The 7-way tester part # TR20117 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...
  • Troubleshooting Fuses Blowing after Replacing Trailer 4-way with 7-Way
    Sounds like there is a short on the vehicle side of the trailer wiring. Check the wiring of the connector on your tow vehicle to see if there is any cut or exposed wire and fix as necessary. The short will be on the 7-way side of the wiring of your tow vehicle. What circuit has the 10 amp fuse that is blowing? That will be a good indicator what circuit has the short. I attached a couple trailer wiring FAQ articles for you to check out as well.
    view full answer...
  • Troubleshooting 12 Volt Power Circuit not Functioning on 7-Way After Re-Wire
    There could be corrosion or dirt inside your 7-way that needs to be cleaned out before all of the circuits of the 7-way will activate. That's the most common reason circuits on a 7-way won't function properly. You can test this easily by using a circuit tester like our part # 3808 to test the wires that feed into the 7-way on the circuits that aren't functioning. If the wires have voltage but not the pins the problem is corrosion or dirt on the inside or outside of the connector. Also,...
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  • No Power to 7-Way Trailer Connector on a 2004 Ford F-150
    It sounds like a possible tow package fuse has blown on your 2004 Ford F-150. You will want to use the truck owners manual to find the locations of all fuses/relays associated with the tow package wiring to check them. The 12 volt pin on a 7-Way does not affect the regular trailer lights and the fact that everything stopped working with the interior lights is what makes me think the issue is related to the tow package fuses (specifically the one that controls the 12 volt circuit on the...
    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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  • 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 # TR20117. Check out the review video I attached for more information.
    view full answer...
  • 2011 Ram Trailer Wiring and Fuse Location
    On your 2011 Ram , the brake controller pin is at the 5 o'clock position. I've attached a photo to assist with all the function locations. You can use s 7-way tester like # TR20117 to check functions. There is a fuse for your running lights and from what I could find in the online version of the owners manual, the trailer tow lamps/park lamps fuse is in cavity J14 and requires a blue 20 amp cartridge fuse.
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    Image 1 for
  • Can 7-Way Trailer Connector Vehicle Tester be Used on a 2007 Chevy Silverado
    Yes, you can use 7-Way vehicle side trailer connector tester # TR20117 on any RV style 7-Way trailer connector, also called a 7-Way blade style connector, including the one on your 2007 Chevy Silverado!
    view full answer...
  • Can LED Indicator Part of 7-Way Circuit Tester TR20117 be Rotated 180 Degrees
    Yes! You can rotate the LED indicator part of circuit tester # TR20117. I pulled one from the warehouse to make sure. All you have to do is loosen the set screw holding it in place, rotate it, and tighten the screw back down. Pretty neat.
    view full answer...
  • Does 7 Way Trailer Connector Tester # TR20117 Test 12 Volt Accessory Circuit for Interior Lights
    Yes, the 7 Way Trailer Connector Vehicle Tester # TR20117 that you referenced does have the ability to test the 12 volt power circuit of your 7-way. That is the circuit that controls the interior lights of your trailer. On the tester it would be the LED labelled 12V which stands for 12 volt. I attached a picture that points this out. It should be lit up all the time.
    view full answer...
    Image 1 for
  • 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...
  • Why Are the LED Indicator Lights Not Show in the Correct Positions for Tow Circuit Tester TR20117
    The layout of the LED indicators just happens to be arranged that way but the pins for the various functions are all still in the standard 7-Way configuration. The vehicle we tested it on, shown in the video I have linked, has a standard 7-Way and the tester worked flawlessly.
    view full answer...
  • Using Tow Ready Trailer Connector Tester Part # TR20117 to Diagnose OEM Brake Controller Problem
    The Tow Ready 7-Way Connector Tester will draw enough power to simulate a trailer. Another option would be to try a different trailer on your truck. If the same problems appear, you will have eliminated the trailer as being the problem. I would also recommend you check the trailer connector on the vehicle and the trailer, making sure neither is damaged or corroded. If you can see any white or green corrosion on the pins or sockets of the connectors, there is a chance that the corrosion...
    view full answer...
  • 7 Way Trailer Connector Vehicle Tester For 2020 Ford F-150 With OEM Trailer Brake Controller
    Yes, the 7 Way Trailer Connector Vehicle Tester # TR20117 is specifically designed to work with the OEM integrated brake controller on your 2020 Ford F-150 with the tow package and pro backup assist. It may or may not work with other vehicle manufacturers OEM controllers if you are wanting to use it with multiple vehicles.
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  • Where Are the Trailer Light Fuses On a 2008 Ford F-350
    The trailer tow fuses/relays for your 2008 Ford F-350 are all located in the power distribution center (PDC) which can be found under the hood, next to your engine. I have attached these locations for you below but for future reference they are listed in your owner's manual. #20 - Relay - Left Stop/Turn Trailer Tow #21 - Relay - Right Stop/Turn Trailer Tow #34 - 25 Amp Fuse - Stop/Turn Trailer Tow Relay #42 - 30 Amp Fuse - Park Lights Trailer Tow Relay #55 - Relay - Park Lights Trailer Tow
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  • 12 Volt and Reverse Light Circuits Not Working on 1999 Ford F-250 Tow Package
    There are also relays associated with the reverse light and 12 volt circuits for the tow package wiring on a 1999 Ford F-250. There are also multiple fuses for each. If any one of them is bad or missing then that circuit will not work. The relays are in locations 38 and 39 in the fuse panel so those are the first to check. There are also a fuses in locations 4 and 16 in the under hood panel and in location 28 in the in-cab fuse panel.
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  • Troubleshooting Power to 12 Volt Terminal on 7-Way of 2005 Chevy Silverado
    The 1:00 terminal on your 2005 Chevy Silverado 2500 is the 12 volt power terminal. If you are not getting power, check the fuse in the power distribution box under the hood of your truck as you will likely just need to replace this fuse. I was unable to locate the exact placement of the fuse in the online copy of the owner's manual I found so are going to want to check your owner's manual to verify. You are also going to need to make a connection under your hood to activate that circuit;...
    view full answer...
  • Trailer Fuse Locations on a 2018 Ford F-150
    In the passenger compartment fuse panel the fuse in location 4 is for the trailer brake control. Try checking this on your 2018 Ford F-150 to see if that takes care of your problem. In addition to the fuses in positions 24 and 30 in your engine compartment you can also check locations 43, 53, and 74. I have also attached a link to our fitguide for your pickup in the event that you are needing additional products to tow your trailer.
    view full answer...

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