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Cordless Circuit Tester

Cordless Circuit Tester

Item # PTW2979
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  • Reviews (11)
  • Q & A (0)
  • Videos (1)
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  • Why etrailer?

Performance Tool Electrical Tools - PTW2979

  • Testers
  • Circuit Tester
  • Performance Tool

  • Performance Tool cordless circuit tester detects voltage from 3v to 28v
  • Ground wire or clip is not required
  • Safe with ECMs, sensors, transducers, and the like
  • 2 Type "N" long-life batteries included
  • Buzzes and lights up if power is detected when the tester is grounded
  • Overall length: 6"

W2979 Cordless Circuit Tester

California residents: click here

Video of Cordless Circuit Tester

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

Video Transcript for Performance Tool Cordless Circuit Tester Review

Today we'll be taking a look at the Performance Tools Cordless Circuit Tester, part number PTW2979. Now this is going to be your Performance Tool Circuit Tester. It's going to be a handy little thing that's only about 6 inches long. It detects voltage from 3 volts all the way up to 28 volts. The nice thing about this is it's going to be cordless. It's going to use you as the ground so you're not going to need a wire or a clip with it.

It's going to be safe to use on ECMs, sensors, and transducers as well. It comes with 2 end type long term, long life batteries. Now here we'll go ahead and test it out. It does come with your probe as well, so if you like to just press that on to your wires and then probe your wires you can. If you have a four-pole like we do here, you can just remove that cover, hold it on the chrome or shiny part here. Then you're just going to touch the ground.

This is going to use you as a ground, so if we don't touch the ground, we're not going to get anything out of it. If we touch the ground with our finger with our freehand, you'll hear the audible beep as well as see the light flash. Now, if we let off that ground . So you'll know right away if you have a bad ground. That will do it for our review of the Performance Tools Cordless Circuit Tester, part number PTW2979..

Customer Reviews

Cordless Circuit Tester - PTW2979

Average Customer Rating:  4.6 out of 5 stars   (11 Customer Reviews)


I wasn't sure how this would work but I was pleasantly surprised. Handy tool to have.


I lost a $75 Snap-On circuit tester and bought this one to replace it. Not only is this tester easier to use but the cost is less than a third of the Snap-On version.


Everything was as advertised, and thank you Kaylyn R for your wonderful customer service. It took awhile to get everything installed, because of crazy events in the past year, but it all works great!


Delivery was as said and product as described.



Still using it on occasion. Have to watch the batteries.


Great products and great people to deal with.


Seems to work well, and my order was processed extremely fast. Great service!




Works good as stated! Delivery was longer than expected.




Ask the Experts about this Performance Tool Electrical Tools

  • Trailer Blinker and Turn Signals Only Work on One Side
    Since it sounds like you were trying to match up colors during your install I believe you are correct that you wired it incorrectly. Although there are common wiring colors, there are no rules saying that everything has to be wired using any specific colors. This goes for both vehicle and trailer side. If you connect wire colors instead of checking their functions you could end up with an incorrect wiring system. What I recommend doing is using a Circuit Tester # PTW2979 to test the function...
    view full answer...
  • Interior Lights Not Working on a 1998 Sooner Horse Trailer
    If all of the other functions on your trailer are working correctly, then you most likely have a short or a bad ground on the wiring that your interior lights are connected to. You can trace it all the way to the trailer connector on your horse trailer and look for any places where the wire might be bent, damaged, corroded, or exposed and replace it or fix it. Another way to test and see if that is the problem is to test the pin on your tow vehicle side connector that is used for 12V...
    view full answer...
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  • Troubleshooting Trailer Lights Working After Trailer Tongue is Moved Up and Down
    If you are having to wiggle wires around before they start to work on your trailer then you definitely have a short or a bad ground somewhere on your tow vehicle or trailer. It can also mean that you have corrosion somewhere on your wiring as well. Start off by checking the connectors and make sure that they don't have any corrosion or debris built up. You can determine which one it is by using a Circuit Tester # PTW2979 to test each of the functions on the connector for your tow vehicle....
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  • Trailer Lighting is Getting Power But Lights are Not Working When Connected to 2008 Chevy Silverado
    If you are getting power to the connector on your 2008 Chevrolet Silverado and you have tested and found that there is power on the wires that go to the lights themselves, then it sounds like you have a short somewhere - most likely near the lights. You can verify this by using an alternate power source, like the battery from your Chevy, and test the different functions on your trailer connector. You can also check the connector on both your Chevy and your trailer to make sure there is...
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  • Can Performance Tool Wiring # PTW2979 be Used on More than Trailer Applications
    The Cordless Circuit Tester # PTW2979 is not limited to only trailer circuit testing. You can use it in basically any application that has voltage between 3 volt to 28 volt. I attached a review video for this for you to check out as well.
    view full answer...
  • Determining Wire Functions on Truck and Trailer with Non-Standard Colors
    When adding a trailer wiring harness to a truck or trailer it's always best to make connections based on function, not color. This is especially the case in situations like yours where non-standard wire colors are used. On your truck you can use a circuit tester like # PTW2979 to test the wires you mentioned while you have a buddy run through the lighting functions in the cab. You will just need to find which wire gets power with each corresponding light function (running lights, brake...
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  • Troubleshooting Trailer Brakes In Over Load
    Since you recently replaced the brake controller you will want to do a quick check there. They have to be mounted in the direction of travel, cannot be tilted or turned side to side, and usually have to stay within a certain range pointed nose up or down. If that is off, it can cause the brake controller to perform erratically. Next I would try some testing. Disconnect the trailer from the vehicle, then use a circuit tester like # PTW2979 if needed to test the connector on the vehicle....
    view full answer...
  • Weak Trailer Brakes When Using The OEM Brake Controller
    If you connected a separate 12v source to the trailer and the brakes seem to work fine then it could be your factory brake controller itself. There has been issues with factory brake controllers on the Ram trucks. In order to connect an aftermarket brake controller to the Ram truck the factory brake controller has to be disabled by an authorized dealer or the two will interfere with each other. It sound as if the power wire coming from the factory brake controller has a weak spot or a short....
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  • Why Is My Brake Controller Running Hot And Locking Up Overnight
    It sounds like your brake pin has constant 12V power and it should not. You will need a circuit tester, such as the Cordless Circuit Tester, part # PTW2979, so you can check the voltage on the brake output pin on your 7-way connector. This pin should be at the 5 o' Clock position on your 7-way connector. My guess is when you test that connector you will find that it reads 12V, but it should not read anything if the brake controller is not activated. I have attached a diagram that shows...
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  • Trailer Brakes Have Power But Do Not Work
    In order to find out what the issue is, we will run through some troubleshooting to properly deduce the problem. Start by cutting the blue wire on your brake controller and check for continuity with a circuit tester like # PTW2979 when you apply the manual override or when you depress the brake pedal. If that checks out, then reconnect the blue wire and move to the truck side trailer connector. Ensure the connector is clean and free of rust, dirt, or corrosion. At this time you need to...
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  • Troubleshooting Turn Signal Not Working on Trailer
    I can give you some troubleshooting steps to take to try and find out what is wrong with your turn signal. In order to determine the specific problem you will need to purchase a circuit tester if you do not have one - the very handy Cordless Circuit Tester # PTW2979 would be my strong recommendation due to how easy it is to use - and test the connector on your vehicle after disconnecting it from your trailer. Check the wiring going into your harness from your tail lights to see if the turn...
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  • No Power to 12 Volt or Trailer Brakes on 2015 Ford F-350
    The first thing to do is take a look at your owner's manual to locate any trailer fuses or relays and ensure they are all there and in working order. If they are, in order to determine the specific problem you will need to purchase a circuit tester if you do not have one - the very handy Cordless Circuit Tester # PTW2979 would be my strong recommendation due to how easy it is to use - and test the connector on your vehicle after disconnecting it from your trailer. Check the wiring going...
    view full answer...
  • Troubleshooting Trailer Lights not Working Properly
    The first thing to do is take a look at your owner's manual to locate any trailer fuses or relays and ensure they are all there and in working order. If they are, in order to determine the specific problem you will need to purchase a circuit tester if you do not have one - the very handy Cordless Circuit Tester # PTW2979 would be my strong recommendation due to how easy it is to use - and test the connector on your vehicle after disconnecting it from your trailer. Check the wiring going...
    view full answer...
  • Wiring in a Trailer Brake Controller to a Factory Wiring Harness on a 2012 Toyota Tundra
    The green with white wire is the one I show as connecting to the red wire on the controller. But if you want to be certain, you can test the wires on the factory harness using a circuit tester like # PTW2979 if you need one. One of the remaining wires will attach to the red wire on the controller. This is the input circuit from the brake switch. It tells the controller when you are stepping on the brake pedal. To find which wire is correct, step on the brake pedal while testing the wires...
    view full answer...
  • Right Brake Light Does Not Work After Breakaway Switch Installation
    That is odd that your right rear brake light does not work if they spliced the break away switch battery into your running light circuit. The brake lights and running lights typically run on two different circuits so it should not have been affected. I would recommend checking each of the connection points for possible cuts or frays to other wires nearby. It is possible that they may have accidentally cut or damaged a brake light wire creating a short that would cause your brake light to...
    view full answer...
  • Where to Attach a Red Trailer Brake Controller Wire on a Diesel Motor Home with Air Brakes
    It should be fairly easy to locate the brake light wire to install a brake controller. First check above the brake pedal. If there are wires there you can check that is the best place to start looking. If you have to tap into the control valve then you can test the electrical connections there. In either case you will need a circuit tester like # PTW2979 if you do not already have one. Test the wires at either location. You are looking for the one that shows power to the circuit tester...
    view full answer...
  • Finding the Hot Ignition Switch on a Kawasaki Prairie 700 ATV
    If the wire you see on the ignition switch is a large wire, it may actually have other wires in side of it. What you can do is use a circuit tester like # PTW2979 if needed to locate the correct wire. The correct wire will only show power when the key is in the on position. You could also follow the wire to the starter motor and see if it separates out to 2 wires and test those wires. Bascially the only way to know for sure which wire to connect to would be to test the wires with a circuit...
    view full answer...
  • Both Trailer Turn Signals Blink at the Same Time
    This is normally related to a bad ground connection somewhere. Make sure the main trailer connector ground and the grounds for each of the lights are all connected to clean and corrosion free bare metal surfaces. Also make sure that the vehicle side and trailer side connectors are clean and free of corrosion. If you are using a 4-Way harness then these are the most common issues. If you have a 4-Way but it has 5 wires coming out then this is a wishbone harness and it will have the running...
    view full answer...
  • Trailer Brake/Turn Lights Not Working After Installing Wiring Harness on a 2012 Nissan Frontier
    There are some Nissan vehicles that require an additional relay from a Nissan dealer to make everything fully functional. However if you have found all the relays in the proper places and have installed the relays in wiring harness # 118525 as indicated in the instructions, linked for referenced, and like in the video I have included then there could a problem in a different location. Use a circuit tester like # PTW2979 if you do not already have one to test the 4-Way end of the harness...
    view full answer...
  • Running Lights on Trailer Not Working After Install Wiring Harness on a 2011 Nissan Frontier
    There are a couple of things that could cause problem on the 2011 Nissan Frontier. First, if the truck did not come with the factory tow package then you will need the wiring harness that you have referenced # 118525. This harness comes with 3 relays that activate a 12 volt circuit and the turn signals. Some times there is an additional relay that you will need to get from a Nissan dealer that installs in the in-cab fuse panel. If that additional relay is present then check the fuse that...
    view full answer...
  • No Trailer Brakes with Manual Override or Brake Pedal Using a Tekonsha P2 Brake Controller
    There are several possible causes that could lead to the problem you are having with the P2 brake controller # 90885. The first thing you are going to want to do is sever the blue wire from the back of the controller several inches. Then use a circuit tester such as # PTW2979 if needed to test the end of the blue wire coming out of the controller while you apply the manual override. If the wire shows power during this test then the problem is not with the controller but with the wiring...
    view full answer...
  • Finding the Correct Brake Switch Wire to Install a Trailer Brake Controller on a 2009 Nissan Murano
    To find the correct brake switch wire use a circuit tester like # PTW2979 if needed to test each of the wires you see. You will need the one that shows power only when you apply the brake pedal. If it shows power with the headlights or turn signals on then it is not the correct wire. Take a look at the video I have linked and move forward to about the 9:22 mark. It shows our installer testing for the correct wire.
    view full answer...
  • Trailer Tail Lights Come On for a Few Seconds then Shut Off with a 1996 Jeep Grand Cherokee
    There could be a few reasons why this is happening. The first thing I want you to do is go ahead and disconnect the trailer. Then use a circuit tester, like # PTW2979 if needed, to test the wires leading into the converter box for harness # 118349. Run through all the functions of the vehicle (left/right turn signals, brake lights, and running lights) while testing the wires. If the signals are not correct going in there that indicates a problem with the vehicle wiring that will need to...
    view full answer...
  • No Running Lights on Boat Trailer and Camper Towed by a 2012 Dodge Ram 2500
    The first thing you are going to want to do is use a circuit tester like # PTW2979 if needed and test the connector on your truck to make sure all of the functions are working. If they are not use the owners manual and/or the legend on the power distribution box lid to find the locations of any fuses or relays related to the tow package wiring and replace any that are faulty. If everything checks out on the truck side then that would indicate problems on the trailers. Most likely there...
    view full answer...

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Info for this part was:

Employee Jameson C
Expert Research:
Jameson C
Employee Jacob T
Video Edited:
Jacob T
Employee Dustin K
Video by:
Dustin K
Employee Wilson B
Updated by:
Wilson B
Employee Erin H
Updated by:
Erin H
Employee Jared G
Installed by:
Jared G
Employee Jacob W
Written by:
Jacob W

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