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Circuit Tester Kit

Circuit Tester Kit

Item # 40376
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Wiring 40376 - Circuit Tester,Test Light - Draw-Tite
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Circuit Tester Kit Lowest Prices for the best wiring from Draw-Tite. Circuit Tester Kit part number 40376 can be ordered online at etrailer.com or call 800-298-8924 for expert service.
  • All Info
  • Reviews (19)
  • Q & A (4323)
  • Videos (2)
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  • Why etrailer?

Draw-Tite Wiring - 40376

  • Tools for Wiring
  • Testers
  • Draw-Tite
  • Circuit Tester
  • Test Light

Circuit Tester Kit


Features:

  • Heavy-duty tester signals with a light and a buzzer
  • Tests low voltage up to 28 volts
  • Finds electrical shorts
  • Checks circuits from a distance
  • Checks polarity
  • Checks battery drain
  • Kit includes:
    • Alligator clip
    • Hook


40376 Circuit Tester Kit




California residents: click here


Video of Circuit Tester Kit

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




Video Transcript for Circuit Testing a Vehicle 4-Pole

Today Im going to show you how to test the functionality of a trailer four-way connectors. What youre going to need to do this is a circuit tester and a buddy in the drivers seat to operate the taillight functions. The first thing were going to test is the taillights themselves. Hit the taillights. (beeping) that means thats working. The next thing were going to test is the left blinker.

(beeping) That works. Then were going to test the brake light function on that side as well. So, hit the brakes. (beeping) That works. Then for the right blinker (beeping).

Now the right brake (beeping). Now we know that this four-way connector is functioning.


Customer Reviews

Circuit Tester Kit - 40376

Average Customer Rating:  5.0 out of 5 stars   (19 Customer Reviews)

Circuit Tester Kit

- 40376
by:

Easy to use voltage indicator. Flashes and beeps so you hear and see . Made the job so much easier. The coiled cord is really long and makes it very convenient. 776948



- 40376
by:

Purchased this to troubleshoot existing truck wiring and wiring I installed. Much more convenient than using my volt-ohm meter (VOM). 585992



- 40376
by:

Seems expensive for what it does but sometime these one-function devices can save you a lot of money. This is my case. My 2003 GMC Sierra doesn't fall into any category on this website -- at least I couldn't find any good info -- it's somewhere between 2002 and 2004 as far as towing package is concerned. This device allowed me to figure it all out. 901932



- 40376
by:

Excellent service and attention to detail. I would highly recommend purchasing from etrailer. Prices are great and they have a wide selection of information that helps with the purchase decision. Very impressed. 551374



- 40376
by:

Excellent quality circuit tester. Can check battery drainage and troubleshoot wiring shorts. 498087



- 40376
by:

worked great for the purpose check wiring on trailer 422465



- 40376
by:

Well made, clear instructions and very useful for sorting out trailer wires. If you have several trailers and multiple towing vehicles this is real handy! 413164



- 40376
by:

Great product 376271


Comments
Great product
Kej263 - 05/04/2018

38106

- 40376
by:

Ordered several electrical connectors,wire and a wire tester .. all items came in good condition ,looking forward to using the tester as soon as I can I am sure it will do the job. 359795



- 40376
by:

I have placed several orders with e-trailer over time and keep returning. I have gotten ffast response on questions and all orders have been filled correctly an on time. 274120



- 40376
by:

Looks good 235043



- 40376
by:

This is my second Lisle circuit tester. I purchased to replace a unit I lost. These are very well made and worth the extra spend. The Customer Service from e-trailer is second to none and I'm a repeat customer due to the help these folks will render. 228513


Comments
Still works well and is still in great shape. Thanks for asking.
Scott P - 09/29/2016

21328

- 40376
by:

This circuit tester was worth every penny. The audio and light indicators took all the guesswork out of the wiring. It made it easy to identify turn signal and brake wires and I was able to test for proper functionality in my trailer contact once everything was installed. Highly recommended. 180242



- 40376
by:

This really is the ultimate circuit tester! The audible feature is a huge benefit when working alone and energizing a circuit remotely.... saved me multiple trips between truck cab and trailer tail lights! When working on trailer light circuits, this is a must have tool! 84638



- 40376
by:

This tester is well made and definitely worth the money. Makes troubleshooting wiring problems a breeze. 84363



- 40376
by:

High quality equipment! Thanks etrailer.com for the excellent service. 66038



- 40376
by:

Product were just explained. always a great job. i enjoy doing business with etrailer. 64106



- 40376
by:

Very nice tester. Heavier duty than the cheap ones you buy at local retail stores. I like the fact that it also has the audible tone along with the light. 33136



- 40376
by:

Great tester 31427


19
19

Ask the Experts about this Draw-Tite Wiring

  • Installing a Towed Vehicle Battery Switched Charging Line on 2016 Ford F53 Chassis Motorhome
    For your 2016 Coachmen Mirada 35LS, to find a switched power line I recommend using a circuit tester like # 40376. Then you will use the Roadmaster Battery Charge Line Kit for Motorhomes # RM-156-75 with solenoid # TR118665 after the circuit breaker with the center post connected to your switched power line. This with make sure that power is only drawn from the motorhome when the ignition switch of your Coachmen is turned on. Then on the towed vehicle (toad) side you can use the Roadmaster...
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  • How To Install a Brake Controller on 2017 Mercedes-Benz Sprinter 3500
    You can hard-wire in a brake controller and it seems that there are not a lot of the Sprinter 3500 models that are pre-wired, at least from what I've seen in my research. I have not seen any reports that this isn't possible, and we even have an installation video to walk you through the process. The way to find out whether or not the plug is present by using a circuit tester like the # 40476 and testing for a hot wire when the brake is pressed- it's possible that one of the plugs that...
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  • Installing a Brake Controller on a 2015 Ford Transit T250 with Factory Tow Package
    To the best of our knowledge there is no plug-in adapter that will work on your 2015 Ford Transit T250. There should be a bundle of wires under the driver side dash that you can connect the adapter that you have picture to. Simply cut off the end that doesn't connect to your brake controller and use a circuit tester like part # 40376 to test for the following functions that you can splice your harness to: Blue - Brake Controller Output Black - 12V Power White - Ground Red - COLD Side...
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  • Does 12-V Trailer Connector Circuit at 7-way on 2017 Ford F350 Remain Active With Vehicle Running
    Once the trailer is plugged in and the brake pedal is depressed, the 12-volt power circuit on the trailer connector will become active, and can be used for whatever purposes you wish. Keep in mind that this circuit can maintain a trailer battery, but it won't have the available grunt to charge a discharged battery. To fully charge the battery while the tow vehicle is running, you'll need a DC to DC charger like # 331-BCDC1240D for a 40 amp or # 331-BCDC1250D for a 50 amp charger. If you...
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  • Troubleshooting RV Electric Brakes That Do Not Engage
    Since you have tried your truck with another RV trailer and found that trailer's brakes worked fine with your truck and its brake controller this suggests the problem is on the trailer side. There is a simple test you can do on your trailer's brakes that needs only a well-charged battery, such as the one in your truck. If you connect wires to the battery and directly apply their other ends to the brake and ground contacts on the trailer's 7-way (see photo please) all brakes on the trailer...
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  • Troubleshooting RV Backup Lights Staying on When Towed Car is Connected
    The most likely cause for the RV backup lights to suddenly stay on when your towed vehicle is connected is corrosion in the RV connector. In a 7-way socket (please see photo) the 12V power contact at the 1:00 position and the backup light contact in the center can become bridged together. This can occur from corrosion on the inside of the connector or from trapped water or other foreign material that connects these two circuits. You can try an aerosol electrical contact cleaner like...
    view full answer...
  • Trailers Electric Brakes Not Functioning, But Show 12V at Brake Signal Wire on Brake Assembly
    Since full power is reaching your trailer's brakes, but they are not working properly, I recommend checking the ground for each brake assembly. It is important that the brakes are grounded to a clean, bare metal surface of the trailer. Dirt, corrosion, and rust can all interfere with a ground. If they are not already, I recommend grounding all of the brake assemblies to the trailer's main ground. You can use 10 gauge wire # 10-1-1, to route all of the brake assemblies' grounds to the...
    view full answer...
  • Trailer Brake Controller Works with Manual Override but Not with Brake Pedal
    Since the controller is activating the trailer brakes when you use the manual override that means that the trailer battery not being connected is not the problem. Both the brake pedal and the manual override will tell the controller to send back power on the same wire so that battery is not the problem. Although you should have it connected for safety. When a controller works with the manual override but not the brake pedal that indicates a problem on the red wire. The red wire is the...
    view full answer...
  • Recommended Replacement Electric Brakes for 7,000 lb Tandem Axles
    For a pair of 7,000 lb tandem axles I recommend the Dexter Nev-R-Adjust Electric Trailer Brake Kit # 23-464-465. These brakes are 12" diameter x 2" wide and will work with your 5 bolt mounting flange and 16" wheels. These brake assemblies are rated specifically for use with 7,000 lb axles instead of some brakes which can work with axles that have a wide range of capacity, such as between 5,200 lbs and 7,000 lbs. The only thing you need in addition to these brakes is Mounting Bolts...
    view full answer...
  • Troubleshooting Trailer Connection Issues on 2012 GMC Yukon Denali
    The Circuit Tester Kit # 40376 will work well to determine when power is or is not coming from your vehicle. The owners manual shows fuse 3, 6, 10, 25 as trailer fuses. I recommend checking the fuses and then testing the 7-way at each pole for functions. If you still don't have the functions, then disconnect the wiring from the back of the connector and check those pins for functions. If you have the functions there, then you can simply replace the trailer connector with # C55774.
    view full answer...
  • Troubleshooting Weak Ground Connection That Causes Lighting Malfunction
    What you describe sounds like a classic grounding problem. It often happens that some light functions on a trailer will work under some conditions, but stop working when other lights are activated. Tail lights are especially likely to cause this issue because they draw more current. Tail lights draw more current because they stay on, unlike brake and turn lights that are generally on for only brief moments. The fact that your jumper wire corrects for this problem pretty much confirms...
    view full answer...
  • Wiring Third Brake Light for Truck Camper Shell
    The first thing you want to do is check above the spare tire on your 2014 GMC Sierra 1500 for a wire loom and there may be a light blue wire that is the lead for your third brake light; you do need to verify this with the use of a circuit tester such as # PTW2992. If that is not there you will simply need to add the Pacer Performance 3rd Brake Light Logic Module # PP20-702 and tap into the turn signal circuits of your Sierra. This converter will separate your truck's combined turn signal/brake...
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  • How to Connect Horse Trailer with 6 Way Connector to 7 Way Vehicle Plug
    To start, the colors on the trailer really isn't reliable since someone may have changed the wiring at some point; you'll need to test each circuit individually to verify which function it carries and work from there. I'm attaching a diagram of the typical wiring for a 6 way connection that you can cross reference and determine if your wiring matches up. The difference between a 6 way and 7 way connection is that a 7 way connection has a circuit for the reverse lights on the trailer. Now,...
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  • Blinkers and Brake Lights Quit Working When Headlights are Turned on in 1999 Jeep Cherokee
    It sounds like you have a bad ground or a short in your wiring somewhere. Another possibility is if you have a lot of lights on your trailer it could be causing the lights to overdraw. To find out what end the problem is on you will need to use a Circuit Tester # 40376 to test the different functions on the connector of your 1999 Jeep Cherokee. For your trailer side you will just need to use a different 12V source of power like the battery in your Jeep. Check to see if each function...
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  • Installing an Electric Trailer Brake Controller in a Class A Motorhome with Air Brakes
    From my research your 2007 Fleetwood Revolution LE 40e motorhome has air brakes. However, you can still use an electric brake controller. To install the controller you'll need to wire it into your RV. The black wire connects to the positive post of the battery, the white to ground, the blue wire to the RV's trailer connector in the rear, and the red wire connects to the stop light switch. To find the correct stop light switch wire use a tester, like part # 40376, and find the circuit...
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  • No Right Turn Power on Pin 2 on a 10-Way Connector on a 2007 Jeep Commander
    Thanks for sending a diagram! The fuse panels on your 2007 Jeep Commander are located under the hood and on the lower instrument panel just to the left of the steering column. I did some research on your Jeep and fuse location number 21 (rear turn/taillights) in the front underhood fuse box is a 20 amp yellow mini fuse. Replace if blown. I would still take a look at your owners manual to confirm and I think it's page 399. I would also check your 10-pin connector for any corrosion...
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  • No 12 Volt Power at 7-Way on a 2017 Ford F-350
    In order for the 12 volt circuit on the 7-way in your 2017 Ford F-350 to receive power, you will need to activate this in the information center on your dash. Please note that once this is done the 12 volt circuit on the 7-way will still not show power until the trailer is connected. If you have activated the 7-way in the information center and are testing the 12 volt power while a trailer is connected and still not getting a reading then you may want to check the fuses in your fuse...
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  • Replacement Parts for a Fan-Tastic Vent Fan 6600R
    I called my contact at Fan-Tastic Vent and they informed me that there are no longer any replacement parts available for the Fan-Tastic Vent Fan 6600R due to its age. I would first check to make sure none of the wires are pinched and that the lift motor is receiving power by probing the wires with a circuit tester like part # 40376. If it turns out that it is not a pinched wire and the motor is bad then you will need to replace the entire unit. For a direct replacement, I recommend the...
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  • Trailer Turn Signals Not Working with Curt Trailer Wiring Harness on 2000 Toyota Sienna
    The turn signals and brake lights are on the same circuits but the running lights are on a separate circuit. The brake lights working but not the turn signals is strange since they are on the same circuit. You will need to test the wiring harness to determine if the problem is in the converter or elsewhere. Basically you will use a circuit tester such as # 40376 to test the wires going into and coming out of the converter box. First test the wires going into the converter. If everything...
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  • Trailer Brake Controller Installation in 2017 Mercedes-Benz Sprinter 2500
    There is no plug-and-play brake controller harness for the 2017 Mercedes-Benz Sprinter 2500 so brake controller installation will be a hard-wire process. Under the driver's seat there should be a green plug. The wires to this plug can be tested with a circuit tester like # 40376 to confirm their function since vehicle wire colors are not always consistent. A brake controller like the Prodigy P2 # 90885 has 4 wires that require connection to the Sprinter. The black wire is 12V...
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  • Electric Brakes Not Working when with Factory Brake Controller on 2013 Silverado and 2014 Yukon
    Since we know that the trailer brakes do work since they work with your 2011 Ford F-150, the issue must be with the factory brake controllers in the 2013 Silverado and 2014 GMC Yukon XL Denali. The fact that they are GM vehicles is a clue. Sometimes, for whatever reason, GM will not make the tow package fully functional at the factory. You would have to make some connections under the hood. Even though I have not heard of this being an issue on models with factory installed brake controllers,...
    view full answer...
  • Why Would Trailer Brake Controller and Taillights Not Function on New Trailer
    Sounds like the new trailer needs to be grounded better or is just missing the ground all together. If all of the lights don't work and no brake controller the one thing they all have in common is the ground circuit. Most likely it's the main ground strap from the connector to the trailer frame. Make sure it's connected to a clean metal surface. I attached a couple help articles for you to check out.
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  • Trailer Breakaway System Battery Requirements for 5th Wheel
    A trailer breakaway system must have a dedicated battery on the trailer. If it did not have its own battery the breakaway system would not operate if the trailer connector disconnected from the vehicle. A dedicated breakaway battery is required so that an uncoupled trailer's brakes will activate to bring it to a stop, but a second backup battery on the trailer is not required. I linked our main page for trailer breakaway kits. We offer basic kits like # C52026 and kits with a built-in...
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  • Wiring a 4-Way Flat Connector on a 1987 S-10 Blazer
    It sounds to me like you have a bad ground connection that is causing the problem. Sometimes a plastic license plate holder will cause this situation and it can show up in a number of ways with the lighting. Check all of your ground points and make sure the trailer lights are grounded good to the trailer frame and you will probably solve the issue. If this does not work then you will need to use a circuit tester, item # 40376 if you need one, and check the 4-way connector at the rear...
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  • Where Is Fuse Located For Trailer 12V Power For 2004 Chevrolet Silverado
    I have attached a drawing that shows how the 7-way wiring should be run. As the drawing shows, the Black 12V wire coming from the back of the trailer connector is run to the positive battery post with a 40 amp circuit breaker. Another way to attach the Black wire is to attach it to the forward-most positive terminal on the fuse block. If you attach the wire to the fuse block you will also need to use a 40 amp fuse in the slot closest to the terminal. I did some research of the fuse...
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  • Parts Needed to Rewire Triple Axle Gooseneck Trailer with Brakes
    Since you mentioned that you want to rewire the whole trailer we will start off with a 7-way connector. For this you can use part # H20046 which will give you 8 ft of wire to start with. I then recommend using a junction box like part # 38656. This will mount to your trailer frame and you will use the posts inside the box to attach the wiring. This will make the rewiring process as easy and clean as possible. Next you will need to figure up how much wiring you will need. In this case...
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  • Brake and Signal Lights Do Not Function When Head Lights are On
    It sounds like you have a bad ground connection. If all ground connections are not making good contact to bare metal, when the tail lights are turned on then the trailer lights will go out or not function properly. You will need to check all of the ground connections especially where the tail lights are mounted to the trailer frame, and where the light brackets are mounted if they are bolted to the frame. If a plastic license plate holder is mounted between the left side taillight and...
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  • Hardwiring a Brake Controller on a 2001 Chevy Blazer without a Factory Tow Package
    The reason you cannot find the 12 volt power and the electric brake wire is because you have to hardwire them yourself. On your 2001 Chevy Blazer, you will have to hardwire the vehicle to install a brake controller. Hardwiring a vehicle may seem like a difficult task, but it really is not too hard. I can guide you through the process. You will need three items in order to install the brake controller. First, you will need the brake controller itself. Second, you will need a 7 and...
    view full answer...
  • How To Install A Brake Controller on a 2009 Ford F-150
    Installing a brake controller system on a 2009 Ford F-150 is very simple thanks to the brake controller port they provide. The port is in a funny location but you simply plug in the brake controller and you are done. The most popular brake controller we carry is the Tekonsha Prodigy. For a Prodigy for your truck, you would use part # 90185 and adapter # 22292 and it will include a wiring harness that will allow you to simply plug the controller into the truck. No cutting, splicing or...
    view full answer...
  • How to Test Tow Package Wiring on 2018 Jeep Grand Cherokee Altitude for Functionality
    It is easy enough to test your 2018 Jeep Grand Cherokee's factory wiring to confirm that it is functioning, even if you do not have a trailer handy. All you need is a simple and inexpensive circuit tester such as # 40376. All you need is the tester and preferably also a helper to assist by activating the various lighting functions on the GC while you have the tester applied to the appropriate pins on the 7-way or 4-pole wiring connector. Please see the linked video. Please refer to...
    view full answer...

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Info for this part was:

Expert Research:
Mike L
Expert Research:
Robert G
Expert Research:
Patrick B
Expert Research:
Michael H
Expert Research:
Jameson C
Expert Research:
John H
Expert Research:
Adam R
Expert Research:
Jeffrey L
Video Edited:
Zack K
Video Edited:
Andrew K
Updated by:
Sarah W
Updated by:
Alexander C

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