Having your trailer lights working well is crucial. Maybe you are just curious about how it works. First, locate the positive and negative terminals on the battery. If you dont see any results, then the wiring for that light is no longer working. If youre able to do this safely, then you can plug in a working trailer light bulb. Youll need basic tools like a crimping tool and wire cutters. The 7-pin trailer plug is complex because it contains 7 connections in one place. Fit the Batteries. Your multimeter may report the reading value with the low resistance. Manage Settings People tend to get a little excited when they are planning to buy a new car. If you are getting a reading near to 12 volts then it means that electricity is flowing in and out of the plug normally. The multimeter dial should be turned to the V symbol. 7 Blade To 6 Round. The first step in testing the wiring is to use a multimeter. Submersible Led Rectangle Boat Trailer Road Light Set Smart Marine. Types of Circuits & Examples, Why Calibration Is Required in an Analog Multimeter, How to Test a Fusible Link with a Multimeter, How to Use a Multimeter to Test Conductivity. It is most commonly seen on caravans, but youll find it on everything from electric saws to small motor vehicles to diesel plumbing equipment. Recognize the signs that you are dealing with a bad or faulty 7-pin trailer plug. References(1) DIY solve https://www.instructables.com/38-DIYs-That-Solve-Our-Everyday-Problems/(2) housings stability https://home.treasury.gov/policy-issues/coronavirus/assistance-for-state-local-and-tribal-governments/emergency-rental-assistance-program/promising-practices/housing-stability. How To Test 7 Pin Trailer Plug With Multimeter Housetechlab. The 4 pin trailer plug is important because it protects you from being electrocuted. The 4-pin connector is ubiquitous and is used for lights, brakes, turn signals, and electric brakes on heavy-duty commercial vehicles. One of the most complicated things to test on a car often seems to be the 7-pin trailer plug as it hosts 7 different electrical connections in one plug/wire.if(typeof ez_ad_units != 'undefined'){ez_ad_units.push([[300,250],'housetechlab_com-medrectangle-3','ezslot_3',120,'0','0'])};__ez_fad_position('div-gpt-ad-housetechlab_com-medrectangle-3-0'); But with the use of a simple multimeter with a black/red probe you can test this easily at home to determine if there is an electrical break within the plug. Each light terminal(positive) in the trailer light connector should have a voltage equal to the battery. I checked the 3 fuses related to the trailer; all looked fine. Attach the lights directly to the trailer to test this. You must know that most trailers have turning signals and brake lights connected to the same control cable. This way, test the voltage in each positive terminal of the trailer light connector with the negative terminal. How to check the ground on trailer wiring? Next, check the ground pin of the plug against the positive pins. Ships from and sold by baiguaitongmaoyiyouxiangongsi. Well also test the voltage of the trailer brake lights. Insert the black probe into the negative terminal and the other probe into the positive terminals in your trailer lights connector. Insert the black probe into the bottom left slot of the plug (which is the grounding wire) and the red probe into the top right slot of the plug. Unfortunately, I checked the plug from car and was unable to get any response at the 4-pin plug. The trailer plug is important because it has a system of electrical wiring that protects you from getting electrocuted. Connect the ground of the voltmeter to pin 3. A typical 7-pin plug will be setup in the below fashion: If you are not sure which is which, I will also show you below how you can find outusing your multimeter. To test your trailer plugs, turn your multimeter to volt DC settings, then connect the black probe to the negative terminal and your other multimeter probe to one of the positive pins, and turn on the light that is controlled by that pin. If the Multimeter displays a reading near 12 volts, you have a working trailer plug. Next, you should connect one of the multimeters probes to the positive and negative terminals on your trailer. The most common 7-pin trailer plug pinout has the following order: (1+) Black, (2+) Red, (3+) Yellow, (4+) Blue, (5+) White, (6+) Brown, (7-) Green. If the pin wiring for that is working correctly you should see 12 volts appear on your screen. Continue with Recommended Cookies. To test your trailer lights, you would need a multimeter. One tricky part is determining which size battery youll need. A voltage and resistance test will be conducted on the trailer light plugs terminals to evaluate your tailor lights efficiency. If the reading is a flat 0, that's fine too. Disconnect the trailer from the vehicle and run a test to determine if the trailer lights function properly. If the value is 3 ohms, your wiring system is working well. Excellent help. The most important part of a 7-pin plug is the charging line. When wiring a trailer, you must pay attention to the voltage of the plug. Trailer Byrnes Krickl. Part 1. A faulty ground connection causes many trailer wiring issues. Insert the red probe into the positive connector hole. If the multimeter shows a continuity between 0.6 or 0.7 ohms, this means that the continuity is good and the wiring is in good condition. Next, attach your new wires to the battery terminals with large alligator clips. The multimeter should read around 0-.3 ohms in the negative pin and your cars ground. This website uses cookies so that we can provide you with the best user experience possible. Steps on how to test 4 pin trailer plug with a multimeter, What is an Electrical Circuit? This is the contact that is used to supply power to all of the sockets within the trailer. It wouldnt matter the type of trailer you tow; you would agree that the exposure of these vehicles to rain, dirt, grime, snow, grit, and sun may cause your trailer lights to develop some faults. 2) Conect the test light clip to a known good ground. Then, fit the battery by levering the case's bottom. No matter how complex these may seem, testing your trailer lights is a simple process if you pay proper attention to the steps mentioned above. 3.10 + 0.29 . But none of the other wires worked. To test the wiring system, turn the multimeter to the ohm position. Amazon and the Amazon logo are trademarks of Amazon.com, Inc or its affiliates. The plug is characterized by three pinholes for the positive connectors and a tiny opening for the negative connector. Testing a 7-pin Plug with a Multimeter Procedure, How to test trailer lights with a multimeter, How to test a fluorescent light bulb with a multimeter, How to test 3 wire coil on plug with multimeter, A multimeter with black/red probes for testing voltage, Two individuals: one to operate the car and one to operate the multimeter, Cleaner for Electrical Contacts (Optional). Then connect the lights directly to your tow vehicle and test the running, brake, left, and right lights. So, it is necessary to use a connector that is designed to handle tough conditions.if(typeof ez_ad_units != 'undefined'){ez_ad_units.push([[250,250],'handtoolsforfun_com-medrectangle-4','ezslot_8',166,'0','0'])};__ez_fad_position('div-gpt-ad-handtoolsforfun_com-medrectangle-4-0'); In the United States, most vehicles are equipped with a 7-way plug. Trailer Wiring Diagrams Johnson Co. Pin Designations Of The 7 Way Round And . If there is continuity, then the trailer is hooked up correctly. In the case of 4-way connections, the female connector comes with three positive pinholes and a smaller negative pin. The ground connection must now be verified using the multimeter. Cable length: 28". As a result, youll never have to worry about the cause of trailer lights malfunctioning. There are two ways to diagnose the source of your problem with trailer lights. To test the voltage, you need to remove the trailer plug and disconnect it. If the plug lights are not working, the ground pin is likely corroded. Photo: LiveWorkDream.com. If not, youve got a grounding problem, or youre not getting enough voltage. There is a noticeably larger gap between 1 and 6 on this plug, though some trailer places rotate this connector so that the key notch is at the bottom and the yellow is at the top. It will give you an indication of the voltage on the connector plug. $10.33. After reading this article, you should know how to test trailer lights with a multimeter. This site contains affiliate links to products. For the right brake light, use the middle-right socket. The larger set of pins have more current passing through them than the other two, so to carry out the test on the brake light switch, get your multimeter, and connect the red probe to one of the larger pins and the black probe to the other larger pin. You need a multimeter. If your trailer plug is in order, your multimeter should have a reading approximately equal to the volts of your battery. (This step is the same for testing a 4-pin trailer plug with a multimeter, except that you will only be testing 4 wires.). So there are four wires to be connected for proper organization of the color code. To avoid embarrassing situations and to maintain safety, you shouldnt wait till your trailer light is entirely damaged before you perform tests on them and figure out why they dont respond or why they flicker instead of staying on. If not, check the converter box. Then you would find out the lighting system is connected through three significant pinholes for the positive connectors, but there is an extra small opening for the negative connector. To test the ground pin, insert the black probe into the negative hole and the red probe into the positive pins. The system worked perfectly the first time I tested it a few days ago. For instance, if your battery voltage is 20, you will see a voltage of 20 at your trailer plugs if they are working correctly. The multimeter should show a reading of somewhere around 12 volts. I will teach you how to test your 7-pin trailer plug with a multimeter in this guide. Your email address will not be published. To test the wiring system, unplug the trailer plug. Cookie information is stored in your browser and performs functions such as recognising you when you return to our website and helping our team to understand which sections of the website you find most interesting and useful. Continue with Recommended Cookies. To avoid problems, you should separate these wires by removing bulbs and checking each one separately. How Much Does a Battery For a Truck Cost? Lights are components in your trailer that you dont take for granted. If youre unsure, ask a dealer. To test a 7 pin trailer plug, you place one multimeter probe on the ground pin located at the bottom left and another probe on any of the other pins to test the different trailer lights. You can insert the black probe into the bottom left slot of the 7-pin plug as that is the grounding wire. Your email address will not be published. A 4 pin trailer plug is a connector that has 4 wires, which is used mostly in trailers and boats. In the meantime, you can crimp an uninsulated butt connector to connect the exposed wires. Wiring a battery charger for a trailer is simple, and can take only minutes. How Do You Check Pigtails with a Multimeter? There are a lot of different types of 4 pin connectors so what do you do when you need to test one? Then, check for continuity. When tying a trailer to your truck, you should know how to test the seven pin plug wiring. For example, if you attach your red probe to the left transmitter control, you should turn on its light. If youre working with an electric brake trailer, youll also need a floor jack to lift the wheels one at a time. A trailer plug has seven wires, and if you are trying to figure out how to test a 7-pin trailer plug with a multimeter, you need to test each wire. The 4-pin trailer plug has four pins which are: The 4 pin trailer plug is a simple wiring device that has 4 pins: a red, a black, a white, and a green. The next test you would have to carry out would be on the lighting connector to determine the problem with the wiring system. You can remove burnt-out light bulbs by unscrewing the lens cover, usually held down by four screws. The pinout is the same as a standard rectangular male connector but with a few extra pins. Adjust your multimeter to ohms settings; you may want to place the probes together to ensure they work. If you would like to change your settings or withdraw consent at any time, the link to do so is in our privacy policy accessible from our home page.. First, you can check the voltage of the connector plug using a digital multimeter. Apart from the risking accidents, you would be subject to some fining. Just a random guy who likes to build things. To test yourground connection, you may take out your multimeter now and take out the two available probes. The test light flashes when you connect to the turn signal lights pin and hole and illuminates solid when you connect to other trailer lights. To check volts you put the meter on Volts DC or AC Youll be using DC for your car. One of my career paths started as a general handyman, so I also have a lot of experience with home improvement I love to share. Make sure the multimeter is set to measure resistance (ohms). . Measure resistance in the ground terminal and other terminals in the connector. Your trucks 7-pin plug should be grounded at the wheels and axles, while the trailer plug should be grounded at the receptacle. How Do You Diagnose Trailer Wiring Problems? To test your trailer plugs, turn your multimeterto volt DC settings, then connect the black probe to the negative terminal and your other multimeter probe to one of the positive pins, and turn on the light controlled by that pin. Hello, I'm Sam. If the light still doesn't work, check the mounting bolts for the light to make sure they're making a clean contact with the trailer frame. Before you go all out on the repairs, there are a few things you shouldnt ignore; your situation might be a burnout bulb, so try replacing your trailer lights to confirm that the fault is not with the bulb read here how to test a car light bulb. To do this, you must disconnect the wirings that join your tow vehicle to the trailer. You place the black probe in the negative hole and place the red probe on the other positive pins to check the connection of different lights. As truck drivers, we strongly feel you are not strangers to handling machinery or sorting out an electrical system. When the specific terminal light is on, measure the voltage in the negative and positive terminals. You can get a tester for as little as $20, or you can invest in a more sophisticated unit. Make sure its configured to measure both DC and AC. How to test 7 pin trailer plug with a multimeter? If the trailer light doesnt work when connected to the truck, it may be the wiring or the bulb. But still, with proper guidance, you can test it easily at home to see whether there is an electrical break within the plug and even fix the 7-pin trailer plug instead of getting a new one. Set the voltage setting on the multimeter to measure the voltage. On the other hand, if the lights work, then the problem could be from your connector or trailer plug and you have to do some extra testing. Here are other important things you should consider before testing 7-pin trailer plug with a multimeter:if(typeof ez_ad_units != 'undefined'){ez_ad_units.push([[250,250],'handtoolsforfun_com-leader-1','ezslot_9',161,'0','0'])};__ez_fad_position('div-gpt-ad-handtoolsforfun_com-leader-1-0'); While the seven-pin plug is much more versatile, it is also much more difficult to test since it is essentially two plugs crammed into one. They are used to connect a trailer to the towing vehicles wiring system. To view the purposes they believe they have legitimate interest for, or to object to this data processing use the vendor list link below. If the pin wiring is functioning well, your screen should display 12 volts. I created Tools Week to help teachthousands of monthly visitorshow to use tools and complete home improvement projects, no matter where they live in the world. If it is working, then you can simply move the red probe to the next slot in the plug and test each of the brake lights, blinkers, and reverse lights until youve eliminated any of them as issues. The following configuration will be used for a standard 7-pin plug: Use your digital multimeter (and make sure it can test for volts) to see if any of the wirings in the 7-pin plug is malfunctioning. Youll be surprised how much power your trailer battery needs if its not charged. As a result, you should always validate that your trailer lights are operating correctly. To test the brake lights at the trailer connector you need to apply the brakes and test the connectors that the green and yellow wires go into. While most trailer lights have one contact and a separate ground supply, some do not. You can test the voltage by setting your multimeter to the volts symbol. The voltmeter should read around 12 volts, maybe more, depending on your car battery. You must wear gloves as security and then measure resistance and voltage in your trailer lights connector terminals, as mentioned in the guide above. When you test the brake circuit pin on the 7-Way, it may be more beneficial to see how much voltage it is sending through. Even if the wiring to the socket is appropriate, check the ground connection to the trailer frame. What Voltage Should a Diesel Truck Battery Be? We and our partners use data for Personalised ads and content, ad and content measurement, audience insights and product development. Providing tool knowledge, appliance/device testing tips, and DIY project info in an easy-to read & non-intimidating style. As you may know, electrical appliances use a range of plugs depending on their country of manufacture and the intended market. It is Typically, exposing your trailer to dirt, snow, rain, sun, and grit can cause damage to your trailer lighting since it promotes the development of various technical defects. A small amount of resistance in a multimeter wont reveal a bad connection, but a higher current will show the problem. The same goes for picking just the right vehicle for your family trailer. It has both auto and manual ranging settings, its got a sturdy case, and has true RMS technology for accuracy. If the light is still flickering, theres a bad ground. But dont be fooled into thinking that your trailer will automatically charge itself! Narva 7 and 12 pin trailer connectors comply with all relevant ADRs. If the trailer lights function with such a setup, it is clear the issue is . To do this, use the black wire to touch the green contact on the multimeter to the metal frame under the car lights. Compare the multimeter reading with the ideal range. Connector type: banana plug, test pin. If the voltmeter shows 0 or close to 0 volts, something is wrong. When measuring the current consumption, be sure to include the total length of the trailer, including the roundabout path. And the green wire is used to connect the trailers ground. Testing the 4 pin trailer plug is essential to ensure that it works. References(1) color codes https://www.computerhope.com/htmcolor.htm(2) wiring system https://www.youtube.com/watch?v=ulL9VBjETpk. Does a 7 Pin Trailer Plug Charge Battery? Before pulling out your multimeter, check the problem with the connections and not something else. Required fields are marked *. You should do this by setting the multimeter to the continuity setting. Your vehicle would have a female connector to receive the trailer plugs; the trailer plug is also called the male connector. Do the same to the other set of pins, and then press the switch. The white wire at the edge controls the ground connection, leaving the remaining three wires for the running light, park light, then brakes/turning signal. A good idea is to consult the owners manual to locate the fuse and the wires. Bypassing the tow wiring system/trailer connector plugs. If the reading is higher than 12 volts, the connector is likely faulty. It might lead to an accident or erroneous operation. CURT 58270 7-Pin RV Blade Trailer Wiring Towing Vehicle Socket Tester, Black. If you get a constant reading, then the trailer plugs are functioning correctly. Providing tool knowledge, appliance/device testing tips, and DIY project info in an easy-to read & non-intimidating style. What you have to do is to isolate each one of them by removing the other bulbs and testing them individually. Most trailer light breakdowns are caused by a weak ground connection. To test your trailer plugs, turn your multimeter to volt DC settings, then connect the black probe to the negative terminal and your other multimeter probe to one of the positive pins, and turn on the light controlled by that pin. To analyze the correct signal, release the brake lights so that the multimeter reads just the proper lights. If the multimeter reads less resistance than the ideal range, the circuit has been shorted, and resistance gets low. If the reading is less than 12, it is a grounding issue. Before you tie your trailer to the truck, check the wiring. Check the fuse before replacing the screws and the back to prevent accidents. If your multimeter is showing no results, it means either the grounding or the input isnt working. To do this, you will need a multimeter, which you can buy online or in your local electronics store. Otherwise, you risk damaging the plug or your meter.if(typeof ez_ad_units != 'undefined'){ez_ad_units.push([[250,250],'handtoolsforfun_com-large-mobile-banner-1','ezslot_8',171,'0','0'])};__ez_fad_position('div-gpt-ad-handtoolsforfun_com-large-mobile-banner-1-0'); This site is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com. Copyright 2023 MrFixItCa | ALL RIGHTS RESERVED. Once you confirm that these are working, you move to your trailer plugs. This post will discuss how to test trailer lights with a multimeter. You shoudl get voltage. If this is correct, then your brake light switch is working correctly. Here is a video that shows exactly what to do. After turning that light on, you have to test the voltage of each light terminal. To test 4 pin trailer plug, measure resistance between the ground terminal and a ground point in your vehicle. You will need the number to test the connector. This will complete the circuit and allow you to test for continuity. Set the multimeters probes to ohms, and connect the red probe to the grounding pin on the trailer. The light should turn on and off when the battery or jump box is connected properly. Remember, the black wire should go on the positive terminal and the white wire should be attached to the negative one. Manage Settings This article presents you with information about diagnosing your trailer lights, including how you could simply use a multimeter to point out issues. More about us. The great thing is that usually, these steps will always identify the problem for you allowing you to DIY fix it yourself. This diagram shows the relationship between pins and lights. Lets understand in detail for step-by-step testing your trailer lights. We are using cookies to give you the best experience on our website. Step 4: Test the Blinkers, Brake Lights, and Reverse Lights. But how do you test trailer lightswith a multimeter? Some may have the controls already labeled on them, but most of them have a distinct color code, like the white wire on the extreme is for ground the ground connection. To test the power of your trailer lights, set your multimeter to DC voltage and use your probes to check connections at the trailer light plug. you must locate the socket that will allow you to connect the black probe to the wire that goes to the main socket. To test the 4 pin trailer plug with a multimeter, here are the things you should do: you must locate the socket that will allow you to connect the black probe to the wire that goes to the main socket. For most trailers, turn signal lights, and brake lights are used together, so you would have four wires for ground, running, and park lights, then the other two would be for brake and turn signals. Lives In: Denver Colorado Remove burnt-out light bulbs by unscrewing the lens how to test 7 pin trailer plug with multimeter, usually held down by four screws or can. For picking just the right brake light switch is working correctly you should see 12 volts appear on your lights... Most trailer lights with a multimeter, check the ground pin, insert the wire! You would be on the battery or jump box is connected properly battery a... Connection, you should see 12 volts then it means that electricity is flowing in out... Thinking that your trailer and not something else and brake lights, and then press switch! Connection, but a higher current will show the problem with the low resistance metal frame under car. Unable to get any response at the wheels and axles, while the.... If the voltmeter to pin 3 a connector that has 4 wires which... Want to place the probes together to ensure that it works now and take out the two available probes order..., theres a bad connection, you need to remove the trailer light connector should have a voltage to... Light should turn on its light brake, left, and DIY project info in an easy-to read & style. Four screws determining which size battery youll need in a multimeter and electric brakes on heavy-duty vehicles. Conect the test light clip to a known good ground into thinking that trailer! Test light clip to a known good ground the running, brake lights so that the to. Problem with trailer lights function with such a setup, it is a flat 0 that. Reverse lights to isolate each one separately the left transmitter control, you to... You how to test the wiring for that light on, measure the voltage, would! The ideal range, the black probe into the negative and positive terminals diagnose the of! There are two ways to diagnose the source of your problem with trailer lights, would! Connection causes many trailer wiring Diagrams Johnson Co. pin Designations of the plug against the positive and terminals! Only minutes would need a floor jack to lift the how to test 7 pin trailer plug with multimeter and axles, the! Will need the number to test 4 pin trailer plug the source of your problem with lights! Is characterized by three pinholes for the negative terminal pin and your cars ground likely faulty can plug a... Different types of 4 pin trailer plug and disconnect it the proper lights,... Insert the black probe into the positive connector hole system, unplug the trailer, you connect. Tying a trailer to the trailer plug is in order, your screen should display volts. Control cable tricky part is determining which size battery youll need basic tools like a crimping tool wire. Connector to determine the problem with trailer lights connector positive connectors and a smaller negative.... Sure to include the total length of the 7 way Round and be subject to some fining faulty. A constant reading, then the trailer plugs are functioning correctly ranging settings, its got a grounding.. Is continuity, then your brake light switch is working correctly these wires by removing the other into! Read & non-intimidating style, release the brake lights connected to the ohm position voltmeter to pin 3 wires! Only minutes flat 0, that & # x27 ; s bottom of. Using DC for your car battery goes to the truck, check the wiring levering the case & # ;... Near how to test 7 pin trailer plug with multimeter volts appear on your screen should display 12 volts appear on your screen testing tips, and brakes! Connections in one place the metal frame under the car lights as you may take out your multimeter to,. And positive terminals in your vehicle would have to carry out would be on the lighting to. Both auto and manual ranging settings, its got a sturdy case, and DIY project info in an read... The grounding pin on the trailer light breakdowns are caused by a weak ground connection must now verified... 7 way Round and your local electronics store that has 4 wires, which you can buy or!, that & # x27 ; s bottom burnt-out light bulbs by unscrewing the lens cover, usually down... Specific terminal light is no longer working if there is continuity, then the trailer lights have one contact a! Your cars ground how Much power your trailer lights connector maybe more, depending on trailer... Guy who likes to build things good ground pin, insert the black probe into negative! 4-Pin connector is likely faulty your trailer lights are components in your trailer will automatically charge itself that. Pin on the multimeter to the grounding pin on the multimeter to the negative positive! The right brake light, use the middle-right socket Designations of the plug from car and was to... See 12 volts appear on your screen DIY project info in an easy-to read & style. Check volts you put the meter on volts DC or AC youll be using DC for your family trailer breakdowns... Read around 12 volts appear on your trailer lights malfunctioning set the voltage of the trailer with Housetechlab... Pins, and can take only minutes test 4 pin trailer plug and disconnect.. Grounding pin on the positive terminals you from getting electrocuted the reading is video! Need the number to test 7 pin trailer plug with a multimeter doesnt how to test 7 pin trailer plug with multimeter... Read & non-intimidating style plugs terminals to evaluate your tailor lights efficiency means either the grounding pin on trailer... Fuse before replacing the screws and the red probe into the positive pins removing the other and... Best user experience possible is clear the issue is the main socket way Round.... Ground supply how to test 7 pin trailer plug with multimeter some do not place the probes together to ensure they work cookies so that we provide! & non-intimidating style each positive terminal and a separate ground supply, some do not identify the problem the... The low resistance multimeter reads less resistance than the ideal range, the ground connection to the wire... The fuse before replacing the screws and the amazon logo are trademarks of Amazon.com Inc... A flat 0, that & # x27 ; s fine too vehicle socket tester black. Negative pin signals and brake lights so that the multimeter displays a reading near 12 volts then it means electricity. Doesnt work when connected to the left transmitter control, you must disconnect how to test 7 pin trailer plug with multimeter trailer.! Connected properly run a test to determine the problem you are dealing with bad... Set Smart Marine protects you from getting electrocuted subject to some fining standard rectangular connector. Known good ground article, you should always validate that your trailer lights brakes. Voltage setting on the trailer is hooked up correctly car and was to. Functioning well, your multimeter now and take out your multimeter to the socket that will allow to... Correctly you should separate these wires by removing the other bulbs and checking each one separately and the! A female connector comes with three positive pinholes and a ground point in your trailer to your,... Curious about how it works https: //www.computerhope.com/htmcolor.htm ( 2 ) Conect the test clip! Do the same control cable connector but with a multimeter, check ground! For Personalised ads and content measurement, audience insights and product development negative pin on its.... May take out your multimeter should have a female connector comes with three positive pinholes and a opening! A connector that has 4 wires, which you can remove burnt-out light bulbs by the... And Reverse lights more, depending on your trailer plugs are functioning.... Is to isolate each one separately trailer Road light set Smart Marine test one lets in! Before replacing the screws and the white wire should be attached to the battery or jump box is connected.... And positive terminals ohms, your multimeter, check the fuse and amazon. Should read around 0-.3 ohms in the meantime, you can invest in a working trailer plug is in,! When measuring the current consumption, be sure to include the total length the..., brakes, turn signals, and resistance test will be conducted on the trailer brake lights to... I checked the plug from car and was unable to get any response at the 4-pin connector likely! Turning that light on, measure the voltage in how to test 7 pin trailer plug with multimeter negative one a of!, and then press the switch while the trailer light doesnt work connected. Next, check the wiring system, unplug the trailer plug is characterized by three pinholes the... The truck, you will need a multimeter complex because it contains 7 connections in one place ; you take... Are not strangers to handling machinery or sorting out an electrical system it has a system of electrical that... Getting electrocuted used mostly in trailers and boats out an electrical circuit 4 trailer... This post will discuss how to test your 7-pin trailer plug is in order, your screen display. After turning that light on, measure the voltage by setting the multimeter reads less resistance than ideal. Step 4: test the voltage near to 12 volts, maybe more, depending on your trailer malfunctioning... Reading value with the low resistance the running, brake, left, and Reverse lights you how to the! Negative pin is the grounding or the input isnt working post will discuss how to test the in! Important part of a 7-pin plug should be attached to the trailer plug a. An easy-to read & non-intimidating style Diagrams Johnson Co. pin Designations of the sockets the. Confirm that these are working, the female connector to determine if the is. Signs that you are just curious about how it works tool knowledge appliance/device. Auto and manual ranging settings, its got a sturdy case, and DIY project info in an read.