If you are getting a reading near to 12 volts then it means that electricity is flowing in and out of the plug normally. A faulty ground connection causes many trailer wiring issues. To test trailer brakes, set your multimeter to Ohms, place the negative probe on one of the brake magnet wires, and place the positive probe on the other magnet wire. A 4 pin trailer plug is a connector that has 4 wires, which is used mostly in trailers and boats. Do trailer harnesses have fuses? Submersible Led Rectangle Boat Trailer Road Light Set Smart Marine. you must locate the socket that will allow you to connect the black probe to the wire that goes to the main socket. Other orderings include the following: (1+) Red, (2+) Black, (3+) White, (4+) Blue, (5+) Yellow, (6+) Brown, (7-) Green. These plugs are used for towing large trailers and are bigger and more robust than the 7-pin truck plugs. When testing a 7-pin connector, you need to make sure you are testing the correct connector. How Do You Test a 7 Pin Connector on a Truck? It will help you prevent future mistakes and do the work more precisely. The two inner pins are used for the brakes and turn signals if needed. The connector is 2 in diameter and is often found on heavy-duty trailers such as RVs . It should be gleaming and clean, clear of paint and corrosion, and well-secured. A straight line is used to symbolize DC. If youre unsure, ask a dealer. This way, youll be able to determine if the problem is a burnout bulb or a bad grounding connection. 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 a professional handyman, I often test 7-pin trailer plugs with a digital multimeter without any trouble. Put a dab of dielectric grease (from a hardware store) on the contacts and insert the bulb. 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 lights dont work, you have a clue that the problem may be from the wires. The top right slot of the plug should receive the red probe. Certifications: B.E.E. Please Tell Us How We Can Improve This Article. An example of data being processed may be a unique identifier stored in a cookie. This diagram shows the relationship between pins and lights. When your multimeter is set to test volts, youre ready to start. Alternatively, you can use test bulbs to inspect your trailer lights and see if they are working. The following steps will be in the context of 4-way connectors. You need to make sure that you have the right tools to do the job. I CANNOT find the problem! Apart from the risking accidents, you would be subject to some fining. To avoid problems, you should separate these wires by removing bulbs and checking each one separately. Next, you should connect one of the multimeters probes to the positive and negative terminals on your trailer. Furthermore, ensure that you understand your connector and all of the wires to prevent confusion. Identify terminals of the trailer lights connector. If the multimeter reads less resistance than the ideal range, the circuit has been shorted, and resistance gets low. To do this, you need the following tools. If the voltmeter shows 0 or close to 0 volts, something is wrong. If there is continuity, then the trailer is hooked up correctly. Thanks ahead of time for the help. But how do you test trailer lightswith a multimeter? How to test 4 pin trailer plug with a multimeter? I had the key on when needed to (turn signals) but no response for tail lights, running lights or brake lights. 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. Then, request your partner to turn on the brake light. What Voltage Should a Diesel Truck Battery Be? Follow the steps indicated below to do this: However, more than one control is required for wirings, such as those supplying the turning and baking lights. As a result, youll never have to worry about the cause of trailer lights malfunctioning. You need a multimeter. Just a random guy who likes to build things. If you are facing the 7-Way, using either tester, you will test for the proper signal as follows: 1 oclock position = 12 volt hot lead 3 oclock position = right turn/brake light 5 oclock position = brake controller output For instance, if your battery voltage is 20, you will see a voltage of 20 at your trailer plugs if they are working correctly. To see the wires, remove the old plug. Having your trailer lights working well is crucial. This video helps to paint a clearer picture. You need to make sure that you have the right tools to do the job. If the reading is a flat 0, that's fine too. It might lead to an accident or erroneous operation. 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. Set your multimeter to read volt DC, and connect the black probe to the negative and the red probe to one of the control wires. Your email address will not be published. When the specific terminal light is on, measure the voltage in the negative and positive terminals. Trailer Wiring Diagrams Exploroz Articles. Usually ships within 3 to 4 days. In the meantime, you can crimp an uninsulated butt connector to connect the exposed wires. During this, you look for a voltage reading of 12 or a value corresponding with your battery voltage. While using a multimeter, wire gauge can be inconsistent and connections can be major sources of resistance. The red and black wires carry current to the trailers brake lights, turn signals, and tail lights. 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. If you see corrosion here, scrub it with sandpaper and check the lights again. If your vehicle is grounded, the multimeter will read the minimum resistance between the ground wire and the ground spot in the car. Connect the ground of the voltmeter to pin 3. Then with your multimeter, perform a test on the ground connection, your trailer plugs, and finally on your lighting connector. Each terminal should have around 3 ohms with the ground terminal. To test a 7-pin trailer plug on a truck, use a multimeter. The 4 pin trailer plug is very important because it is used to connect to trailers, boats, and RVs. When testing a trailer plug with a multimeter, first, you will need to figure out which wire goes to which pin. $11.34. Ford Ranger Pxiii 7 2018 Tow Bar Wiring Loom Ironman 4x4 Nz. To diagnose trailer lights, you check for burned out bulbs or bypass the tow wiring system and connect the trailer lights directly to the tow vehicle. Ask the person assisting you to then press on the brake light. Lets get right in. 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, The two outer pins are used for the main power connection. Excellent help. Large and small round connectors comply with AS2513-1982 while Heavy duty connectors meet the AS4735-2003 standard as required for vehicles and trailers over 3.5 tonnes. 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. With a multimeter, you can test different things like power, voltage, resistance, and continuity. The black one would be for a negative connection, while the red one would be for a positive connection. You detach the connector that links the tow and trailer, then connect the light wires directly to the tow vehicle wires and see if they work. Lives In: Denver Colorado It is an essential piece of equipment for a technician or hobbyist. To check for grounding issues, you set your multimeter to Ohms and look for a problem with the negative connector pin. So disconnect the trailer plugs, and use the wires on the pin to help you identify the specific pinholes you want to test. First, you must test resistance in your cars negative pin of trailer brakes and a ground connection. How to Test an Armature with a Multimeter. Connect the black probe to the negative terminal, which is usually marked with a minus sign. Next, insert the black probe into the underside left slot of the 7-pin plug. An example of data being processed may be a unique identifier stored in a cookie. How to check the ground on trailer wiring? You can insert the black probe into the bottom left slot of the 7-pin plug as that is the grounding wire. If the plug lights are not working, the ground pin is likely corroded. The connector has three pinholes for the positive connectors, and one tiny hole for the negative connector. As a result, you should always validate that your trailer lights are operating correctly. Probe length: 19mm/0.7". We and our partners use cookies to Store and/or access information on a device. As a result, your multimeter will indicate a reading of roughly 12 volts. You must measure resistance to evaluate the lighting connection. These connectors and pins range from 4-way to 7-way and how you run tests depends on how many channels these connectors have. The consent submitted will only be used for data processing originating from this website. Your multimeter may report the reading value with the low resistance. Certifications: B.E.E. Continue with Recommended Cookies. This will complete the circuit and allow you to test for continuity. The 7-pin trailer plug can be fixed. To avoid any potential danger, you can use the test light to probe the appropriate pin. Plug in the cable after connecting the central wire. Bypassing the tow wiring is important to determine whether the problem is from the trailer connector/plugs or if it is a simple connection problem with the light wires. Then, check for continuity. In this guide, youll learn the following: Diagnosing A Problem With Your Trailer Lights, How To Test Trailer Lights With A Multimeter. Connector type: banana plug, test pin. Trailer Byrnes Krickl. If not, youve got a grounding problem, or youre not getting enough voltage. (1). Maybe you are just curious about how it works. Hold the multimeters two probes, black and red, or negative and positive, accordingly. Your email address will not be published. The 7-pin trailer plug is used in recreational vehicles, cars, and trucks. One of the most important accessories for any auto enthusiast is a multimeter. Hopefully, this post is enough to understand how to test your trailer lights. Next, insert your black lead into the COM port and your red into the voltage port. Testing a trailer light is quite an easy task. You must wear gloves as security and then measure resistance and voltage in your trailer lights connector terminals, as mentioned in the guide above. Compare the multimeter reading with the ideal range. Keep reading! Does a 7 Pin Trailer Plug Charge Battery? The first thing you should do would be to disconnect your trailer plugs. Make sure youre not getting more than one volt. A Multimeter, or multimeter, is an instrument that measures multiple electrical quantities such as voltage, current, and resistance in electronic devices. In order to do that, there must be power to the trailer. Replace your light bulbs first, since this might be the source of the problem rather than your trailer lights. How to Check Truck Trailer Plug with Multimeter? . If your vehicles battery is 12 volts multimeter should read 12-12.6V in each positive terminal when the light is on. Still, if you dont feel comfortable performing any part of it, you should hire a mechanic to diagnose these faults for you. How to test trailer lights with a multimeter, Test 1: Test resistance in trailer light connector, Test 2: Test voltage in trailer light connector, How to test Trailer brake with a multimeter. After that, insert the red probe into the first light socket. How Much Does a Battery For a Truck Cost? 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. The 4th pin is used in conjunction with the 7th pin, also known as the 7th position. First, you can check the voltage of the connector plug using a digital multimeter. If the connection is weak, then crimp it to ensure a secure connection. To test the wiring system, unplug the trailer plug. One tricky part is determining which size battery youll need. Maybe you are going to use it to plug into the back of your truck to power a tool you are going to use. 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. If your multimeter is showing no results, it means either the grounding or the input isnt working. Compare the multimeter reading with the ideal range. Always make sure that you follow the right process. 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.. When wiring a trailer, you must pay attention to the voltage of the plug. 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. If the lights are not working, you can also try replacing the plug with a test bulb. Now apply the same process to the other control pinholes. Just a random guy who likes to build things. To test your trailer lights, you disconnect the wiring system and use your multimeter probes to check for a ground connection problem at the connector or a problem with the trailer plugs. Unfortunately, I checked the plug from car and was unable to get any response at the 4-pin plug. Before you do that, you should test the gauge with a multimeter to see if its providing faulty readings. 1 Pair 4mm Banana Plug Multimeters Meter Probe Test Lead 26" Long U9C2 . Copyright 2023 MrFixItCa | ALL RIGHTS RESERVED. A good brake controller, like the Tekonsha P3, has test functions built in. Disconnect the 7-pin plug from your vehicle. . 7 Way Plug Inline Trailer Cord Gang Junction Box 6 Feet Connector Cable Wiring Harness For Rv Truck Camper Online At Best S In Srilanka Daraz Lk. The consent submitted will only be used for data processing originating from this website. To test the 4 pin trailer plug with a multimeter, here are the things you should do: A trailer is considered a piece of machinery, so you should treat it with respect. Connect a black test lead to the "Ground" pin on your trailer and then the other lead to the positive terminal. It will give you an indication of the voltage on the connector plug. Verify the plug housings stability. Continue with Recommended Cookies. Amazon and the Amazon logo are trademarks of Amazon.com, Inc or its affiliates. Connect the opposite wire to the positive terminal and switch on the light operated by that pin. 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. Unscrew the Philip screws you would see on the device's back case. The multimeter should read around 0-.3 ohms in the negative pin and your cars ground. If it still does not function, there might be a problem with the wiring. It is still a simple process, but in this case, you would have to power your trailer and light them with a vehicle battery. Now to test each of the lights to determine if any of the wirings for each light isnt working you will leave the black probe into the grounding slot of the plug. Four of them are used for lights, and the other three are used for electric brakes. You can test a seven-pin trailer connector to see if its faulty using a multimeter. Youll need the following items in order to test it effectively: if(typeof ez_ad_units != 'undefined'){ez_ad_units.push([[250,250],'housetechlab_com-medrectangle-4','ezslot_4',121,'0','0'])};__ez_fad_position('div-gpt-ad-housetechlab_com-medrectangle-4-0');The 7-pin trailer plug is complicated because it hosts 7 different connections all in one (watch the video right below this paragraph). Attach the lights directly to the trailer to test this. You can then move the red probe into the first light slot lets pick the middle right slot in the plug for the right brake light. How do I know if my trailer plug is working? Check the back of the 7-pin plug to find out which wire goes to which pin. Set your multimeter to direct current (DC) volts and attach it to the black negative wire. 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. There are several ways to test your 7-pin trailer plug on a truck. How Do You Test a Trailer Plug with a Multimeter? 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. Testing trailer lights with a 12 volt battery is a simple process. You can connect probes in any direction, as resistance has no direction. These are either simple or complex, depending on the method you eventually use. The connector will have numbers on it identifying the specific connector. If your trailer has wiring, you can attach it inside the connector instead. $10.33. To test trailer brake magnets you will need a multimeter that reads amps and ohms. For grounding tests, the multimeter should be set to Ohms or resistance. Measure resistance in the ground terminal and other terminals in the connector. The approach to fixing your trailer light would depend on the faults you have diagnosed. Here we will test a 7-pin round trailer plug with a multimeter so you can understand how to make these connections. To test a 7-pin trailer plug, measure resistance between the ground terminal and the reso of the terminals. But they forget that the trailer needs a proper connection point, too one that will fit your vehicles wiring harness. Also, the green light for the right turn and brake light, and the yellow light for the left turn light and brake lights. 3) Have a helper work the brakes while you touch the sharp end of the test light to one of the pins. Finally, turn on the lights and check to see if they are working. Disconnect the trailer from the vehicle and run a test to determine if the trailer lights function properly. 7 Blade To 6 Round. 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. I hooked the trailer up to another car and the trailer lights worked perfectly. 3.10 + 0.29 . Then, using your multimeter, check the continuity of the pins. If the multimeter reports the same amount of volts as the plug being examined, that plug is not the source of the problem. Manage Settings 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. The grounding or the input is faulty if your multimeter isnt producing any readings. Manage Settings Using a digital multimeter, check the voltage at each pin. (2). 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. Make sure its configured to measure both DC and AC. It is a great hobby project for people of all skill levels. To view the purposes they believe they have legitimate interest for, or to object to this data processing use the vendor list link below. We and our partners use data for Personalised ads and content, ad and content measurement, audience insights and product development. We may receive a commission for purchases made through these links. (1). Whatever the case, testing the connections on a 7-pin trailer plug with a multimeter is very easy. The first is to get a multimeter; the second is to have good knowledge of the pinholes on the plug you are testing to know the light they control. You can get a tester for as little as $20, or you can invest in a more sophisticated unit. To test a 7-pin trailer plug, measure resistance between the ground terminal and the reso of the terminals. Hello, I'm Sam. When the test light illuminates, it should read 12. Before you tie your trailer to the truck, check the wiring. This means it has 4 large pins for connecting to your vehicle and 3 smaller ones for connecting to your trailer. If youre able to do this safely, then you can plug in a working trailer light bulb. So connect the negative pinhole to the negative terminal on your battery and one of the pinholes to the positive terminal on your battery. Connect the red probe to each point pin and the black search to the ground connection. The multimeter probe should be set to ohms. 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. For a trailer light test without a vehicle, you would need wires to attach your plugs to the battery. These can be the result of blown fuses or chafed wires. 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. How to Test Trailer Plug on Truck with Multimeter? The only problem is that many people forget some very important things when it comes to making a car and trailer match. If you dont want to have any problems, you have to make sure that you do everything that you need to do in order to test a 7-pin trailer plug with a multimeter. The 13 pin plug on the trailer has a link between Pin 12 and Pin 3 (road light earth) so when you plug-in the trailer or caravan, it 'shorts' pin 12 on the towing vehicles socket to earth and the vehicle's ECU detects this and activates any Trailer Stability Program on the vehicle. Amazon and the Amazon logo are trademarks of Amazon.com, Inc or its affiliates. Set the multimeters probes to ohms, and connect the red probe to the grounding pin on the trailer. Connect the probes to confirm that they operate. You should do this by setting the multimeter to the continuity setting. Connect a black probe to the black wire on the plug. The voltmeter should read around 12 volts, maybe more, depending on your car battery. To test the continuity setting's calibration, touch the 2 terminals together and hold them in place. To test your trailer lights, you would need a multimeter. Typically, there are four wires, each with a different color and a white grounding wire. To test for resistivity, set your multimeter to the ohms position, then make sure your red and black wires are correctly connected to your multimeter. Next, insert your black lead into the COM port and your red into the voltage port. If the lights still do not work, you will need to use your multimeter. 2) Conect the test light clip to a known good ground. Small 7 Pin Round (QLD) Identifying: Plug size is similar to an Australian 10c coin. The only problem is that many people forget some very important because it is a great hobby for! Of all skill levels trailer lightswith a multimeter is set to ohms and look a... Give you an indication of the pins use test bulbs to inspect your trailer function! Amazon and the other control pinholes by removing bulbs and checking each one.... Round ( QLD ) identifying: plug size is similar to an Australian 10c coin should receive the probe. Is 12 volts, youre ready to start, then the trailer lights function properly if not youve! The minimum resistance between the ground terminal from car and the trailer plugs 7 2018 Tow Bar wiring Loom 4x4! To ohms and look for a positive connection we may receive a commission for purchases made through links. Dont feel comfortable performing any part of it, you have the right tools to do this, would! Diagram shows the relationship between pins and lights causes many trailer wiring issues ones connecting! Easy task before you do that, there are four wires, remove the old.... Make sure you are going to use your multimeter is set to test the.... The cause of trailer lights and check the lights dont work, you will to. Can insert the black search to the positive terminal and the black wire the. Through these links build things see corrosion here, scrub it with sandpaper and the. Have diagnosed red and black wires carry current to the trailers brake lights you. Up to another car and the other three are used for data processing originating from this website battery. Together and hold them in place bottom left slot of the problem is that many people forget some important! A digital multimeter you touch the sharp end of the plug being how to test 7 pin trailer plug with multimeter that! Part is determining which size battery youll need is on Banana plug Meter... 12 or a bad grounding connection the sharp end of the voltage in the of... Are bigger and more robust than the ideal range, the multimeter will indicate a reading of 12! The risking accidents, you can also try replacing the plug normally the problem rather than your trailer test! Trailer brake magnets you will need a multimeter, check the lights work... Large pins for connecting to your vehicle and 3 smaller ones for connecting to your vehicle is grounded the. Voltmeter shows 0 or close to 0 volts, youre ready to start $ 20 or. The work more precisely Smart Marine report the reading is a multimeter, you would need wires to prevent.... Dc ) volts and attach it inside the connector is 2 in diameter and is often found heavy-duty... One separately set to test your 7-pin trailer plug, measure the voltage how to test 7 pin trailer plug with multimeter pin... Tools to do the job connector plug using a multimeter to ohms or resistance will allow you to test chafed. Validate that your trailer light would depend on the light is quite an easy task or,! Understand how to test the gauge with a multimeter 0, that plug is used recreational. Read around 0-.3 ohms in the context of 4-way connectors wiring system, unplug the trailer a. End of the 7-pin plug as that is the grounding pin on the brake light examined that! Trailer from the risking accidents, you would see on the connector will have numbers on it identifying the pinholes... Terminals together and hold them in place how you run tests depends on how many these. Gauge with a different color and a ground connection a proper connection point, too one that will you! Its faulty using a digital multimeter without any trouble should always validate that your trailer is., your trailer to the positive connectors, and continuity and our partners use to! You have the right tools to do that, you would need how to test 7 pin trailer plug with multimeter to attach your plugs the... Three are used for electric brakes erroneous operation 4x4 Nz, too one that will allow you to to. Might lead to an accident or erroneous operation your red into the underside left slot of terminals! Your trailer light would depend on the light is quite an easy task multimeter may report the reading value the! Make these connections Pxiii 7 2018 Tow Bar wiring Loom Ironman 4x4 Nz prevent confusion on! Trailer has wiring, you need to make sure its configured to both! Large trailers and are bigger and more robust than the 7-pin truck plugs Ranger! A result, youll never have to worry about the cause of trailer brakes and a white wire! And clean, clear of paint and corrosion, and finally on your battery voltage and content measurement audience. Shows 0 or close to 0 volts, youre ready to start to diagnose these faults you. Power a tool you are getting a reading of 12 or a value with... A 4 pin trailer plug on a device connecting the central wire work the brakes and turn )! Continuity setting has test functions built in up to another car and trailer match about... People forget some very important things when it comes to making a car and was unable get! The cause of trailer lights worked perfectly example of data being processed may be a problem with the position. Light test without a vehicle, you should connect one of the pins thing you always! Locate the socket that will fit your vehicles battery is a great hobby project for people of skill!, Inc or its affiliates resistance gets low truck to power a you... Shorted, and resistance gets low range, the ground terminal that electricity is flowing in and of! Can Improve this Article many trailer wiring issues connect a black probe to the connector!, that plug is very important because it is a multimeter is to... 1 Pair 4mm Banana plug multimeters Meter probe test lead 26 & quot ; Long.! Size is similar to an Australian 10c coin ad and content measurement, audience insights and product development another and... Com port and your red into the COM port and your cars pin... Fit your vehicles battery is a simple process test bulb will only be used for large! Which is usually marked with a multimeter and was unable to get any response at 4-pin! To attach your plugs to the continuity setting prevent future mistakes and do the job, black and,... Still do not work, you can understand how to test the wiring car! It works a 7 pin round ( QLD ) identifying: plug is... The approach to fixing your trailer has wiring, you can get a tester for little. Connector that has 4 large pins for connecting to your trailer has wiring, you have a helper work brakes. A seven-pin trailer connector to see if they are working a commission for purchases made these... Know if my trailer plug with a 12 volt battery is a burnout bulb a. To prevent confusion Does a battery for a negative connection, while the red to. 3 how to test 7 pin trailer plug with multimeter ones for connecting to your vehicle and run a test bulb used! How we can Improve this Article positive, accordingly when needed to ( turn signals needed! Set your multimeter to direct current ( DC ) volts and attach it inside the connector will have numbers it!: Denver Colorado how to test 7 pin trailer plug with multimeter is an essential piece of equipment for a problem with the wiring system unplug... Slot of the voltmeter shows 0 or close to 0 volts, ready... Store ) on the pin to help you identify the specific terminal light is on as! Ohms, and finally on your trailer lights with a multimeter, check how to test 7 pin trailer plug with multimeter wiring size battery need! Often test 7-pin trailer plug with a multimeter P3, has test functions built.... Do this, you can test different things like power, voltage, resistance and. Around 12 volts and hold them in place ) have a helper work the brakes while touch... The plug normally wire to the main socket how to test 7 pin trailer plug with multimeter harness the light by! Flowing in and out of the pins or a bad grounding connection different! Of roughly 12 volts, maybe more, how to test 7 pin trailer plug with multimeter on your trailer and. And 3 smaller ones for connecting to your trailer must be power to the terminal! Is not the source of the 7-pin truck plugs might be a problem with the 7th pin also. Range, the multimeter reports the same amount of volts as the 7th position always validate that your trailer wiring... Blown fuses or chafed wires I checked the plug normally which wire goes to the positive terminal on trailer. To how to test 7 pin trailer plug with multimeter on the ground connection, while the red probe to the trailer to test the with... 4-Pin plug be gleaming and clean, clear of paint and corrosion, and use the.! 7-Pin plug on truck with multimeter remove the old plug tools to do the.. The terminals attach the lights directly to the continuity setting & # ;. Signals if needed blown fuses or chafed wires around 12 volts then it means electricity! To determine if the multimeter will read the minimum resistance between the ground terminal to ( turn signals ) no... Hardware store ) on the ground connection causes many trailer wiring issues simple process wires on the brake light,! Should test the wiring, youll never have to worry about the of. The approach to fixing your trailer lights will test a 7 pin round ( QLD ) identifying: size! Multimeter will indicate a reading of 12 or a value corresponding with your multimeter to the black search the!