We then use the ohmmeter to check the resistance after various stages of our testing to see if the thermistor is behaving according to the characteristics of the thermistor. Note that only one wire power wire can run a few circuits on the fuse panel. Parasitic Draw Test on Newer Cars. Anyway the test he had me do was put one probe of the multimeter on one of the big red wires on the heat relay and the other probe on the other big red wire on the heat relay. A good brake controller, like the Tekonsha P3, has test functions built in. A voltage drop test is done on a "live" circuit, meaning that you must create a load in the circuit while taking your readings. Take the positive lead of your multimeter and touch it to the terminal on your glow plug. How to measure current using a multimeter. Again, if your meter is auto-ranging you will only have one dial setting for resistance. Turn on the multimeter and set it to the diode-tester function, as directed by the instructions for your specific model. This is the multimeter I'm using:. PLEASE NOTE: WE DO NOT PUBLISH 3RD PARTY SPAM COMMENTS, TRACK-BACKS OR LINKS. Touch one meter lead to the switch relay socket and the other to the battery negative post. First, use the multimeter leads to check the resistance of the tabs by checking A to B, B to C and then A to C. Leave the red meter lead on the base and move the black lead to the collector. Related Articles: Toggle Switch Wiring. ) Now if you're doing this on a flipper coil (3 lugs), the same theory applies. 7 volts or less indicates a dead battery. Accuracy is another important feature that our multimeters offer. you should hear it in the cockpit of the car. With the help of above mentioned steps we can identify NPN and PNP transistor using multimeter. Photo about electrical, power, electric, tool, multimeter, worker - 93540150 Engineer`s Hands Close-up With A Multimeter Test Industrial Cabinet Of Relay Protection And Automation Stock Photo - Image of electrical, power: 93540150. Features overload protection. Insert the pointed tip of the red test lead first in one hole and then in the other. I want to test to see if it is even good using my ohm meter. Can anyone list which one actually controls what?. Again, if your meter is auto-ranging you will only have one dial setting for resistance. How to test an oil pressure sensor? The oil pressure sensor on my perkins 4108 always reads the same (about 65psi if I recall correctly), irrespective of load, hours run etc. Set the multimeter to the ohms setting X1. Disconnect the high current lead from the positive terminal of the battery and unplug low current connector from the starter relay. Look carefully at the starter relay and its socket. The top 1M and 100k from the meter create a combined PARALLEL resistance of 90k. Short & Isolate Facility Test: In this test we confirm the CT short & isolate facility for correct connection. This is located in the main fuse box under the hood, and should be the largest fuse in there, making it easy to spot. One test is to use a reliable voltage tester or voltage meter to measure the electricity flowing through the circuit. With the relay upside down, place the probes into the terminals labeled "S" and "M". There are many circumstances in which we need to control a high current/voltage load based on the operation of a low-power circuit, such as when using the 5V output of a microcontroller to turn on a 10A, 240V load. Also check for discontinuity between N/C contacts and pole. Pull one out and set it upside down somewhere. Perfect continuity (0 ohms). Just like in everything we do, there is a right and wrong way to test appliances. Jumper Wires You'll need two of them with alligator clips on both ends (you can make these yourself). Insert the pointed tip of the red test lead first in one hole and then in the other. This is the terminal going to the starter. The surest way to test your relays is by using a multimeter to check input, output, and signal voltage. Connect your ground connection on the power supply to the ground pin on the relay. 0024 %, basic 0. Hp Multimeter In Stock | Martin Farm, Business & Industrial Equipment Supply Company. With the alligator clip wires in place on the meter lead ends, clip one test wire to the gas valve (source) and the other one on the exposed copper wire leading to the thermocouple. If the swapped relay doesn't blow the fuse, it's obvious the first relay was shorted to ground. How to Test a Power Window Switch with a Multimeter. If there is not, change the relay. You can also identify the coils pin using multimeter. Re: How to test solenoid with multimeter? The two large posts should read near zero ohms when 12 volts is applied to the small posts but this doesn't take the high current needed for starter. Step 2: With the relay in the vertical position, coil of the relay upwards, check if there is continuity between terminals 1 and 3 of the. To test a relay you have to check its contact changing with continuity testing. Jumper wire may be used between common and open to close the relay circuit for testing and has a test port to easily check voltage. After pressing the pedal in and completing the circuit, voltage should be present at both ends of the brake light switch. Most multimeters include a settings option for measuring current in amps. Identify the terminals anode and cathode of the LED. If possible, secure the lead to the terminal by tucking it inside or underneath the clamping mechanism of the post. 1 Blade-type fuses have test points on top, a good place to meter the voltage in a circuit. Next, take a digital multimeter (DMM) and confirm the findings by using the device in its diode-test mode. Before staring the tests, be sure to thoroughly clean the part first, to eliminate any dust or carbon buildup that might have contributed to it's failure. Considering that you have got hold of the relay switch which is not working properly, here is the actual process: If required, turn the ignition on to energize the specific circuit you intend to test. This allows direct comparison of the drive readout to the meter display. So I'm building a circuit. A continuity test tells us whether two things are electrically connected: if something. To do this, you will have to disable your car's ignition system. It will show the movement in a more visual way than a digital multimeter that only display rapidly changing numbers. These two components are linked together so that when one operates, the other operates at the same time. Some manufacturers place a diagram and pin ID on the outside of the relay case to show which pins are part of the control circuit and which pins are part of the load circuit. This reads zero volts, but I have since read somewhere that you can't use a multimeter to test for power to the coil since the power comes as a pulse from the DME, and thus the multimeter will always read zero volts. The reading should be 5v as show in diagram A. Ask any field or bench technician what their most-used piece of test equipment is and they will probably say a DMM (Digital MultiMeter). A transformer, usually 24 volts, energizes the contactor which has a coil built into it. A diode is forward-biased when the positive (red) test lead is on the anode and the negative (black) test lead is on the cathode. Three-wire sensors with a process current output have a separate wire for ground, signal (4-20 mA), and the power supply. Compare measured resistance to the values in engine manual, If the value is not zero or infinite,the sensor is working ok. How to check the fuses using a multimeter. To determine which model you have remove the outer face plate. Product was successfully added to your shopping cart. Take out a multimeter and place it in the ohmmeter (Ω) setting. A multimeter is a convenience. This is operating the photodiode in photovoltaic mode - like a solar cell. Check the relay before plugging into the tester. The codes are defined as to what system is affected. Tester will check the pin configuration of the unknown relay. Place one probe on the COM terminal and the other probe on the NC Terminal. Move the stalk to either the left directional on position or the right directional on position and test across the center and either of the outer prongs as pictured. I know which ones they are. Experienced and skilled mechanics may test the mower solenoid without using a multimeter. A multimeter set to the Resistance mode (Ω) can be used as an additional diode test or, as mentioned previously, if a multimeter does not include the Diode Test mode. a continuity test is checking of a circuit to see if the current can flow through it or not. If the fuse is not good, replace it. Test the de-energized condition of the relay contacts. It may also be wise to check the relay switch. If it's a lot less than 3 seconds, the cap is open. Relays / Contactors are nothing more than a switch. If you hear a beeping sound and see a sign on the screen of your multimeter, you know that the fuse is in working condition. To make a voltage check on a set of contacts, take a voltage reading from one side of the contacts to the other. When you press the start button it should read zero volts across them, or maybe as high as. This test is for an infinite, two-wire, burner control switch on an electric stove. Jun 21nd 2016 at 8:40PM we will cover how to test the resistance of glow plugs to determine if they are functioning properly. After pressing the pedal in and completing the circuit, voltage should be present at both ends of the brake light switch. When testing relays it’s important to remember they’re not as complicated as they seem and neither is the test procedure. A circuits wiring and connections should have next to no resistance and as such, all voltage should be used through the load. Accordingly, the meter is set to make AC Voltage measurements in the range from zero to 200 Volts. The Reed Relay Multiplexer can close a relay and make a measurement at a maximum rate of 300 channels per second. Ignition relay 1: The bottom right terminal should have voltage when the ignition switch is ON and Start positions, if not the ignition switch is bad. All we need to test a thermistor is an ohmmeter or a multimeter that contains an ohmmeter. A multimeter (analog or digital). You can use a multimeter to check the condition of a capacitor by using its highest range for measuring resistance. Two jumper wires with alligator clips on the ends. Re: Starter relay multimeter test. Re: test a battery charger. Follow along to master the three most basic functions of a multimeter. That is the reason for the sharp probe, and for the sharp teeth on the clip. Resistance, symbolized by the (Ω) symbol and measured in Ohms, is a measurement of how well a current can travel through a circuit or a given path. Test Lead Set, Test Tip Probe to 4mm Right Angle Banana Plug, 1 kV, 10 A, 2 Leads. You also use the low-pass function to check the output frequency of the drive. When checking a normally open relay (with four terminals) with and ohmmeter, no continuity will be shown between two terminals and the other two terminals will show: No continuity. It's on the passenger side fenderwell and it's pretty loud. A multimeter is a versatile tester that measures a variety of electrical properties, such as voltage, amperage, and resistance. Let us see how to test an LED using a digital multimeter. To test a relay to see whether it is good or defective, the simplest way to do would be to use a multimeter set to the ohmmeter setting and Part 2 -How to Bench Test a Ford Relay (Large Relay). You can also measure the resistance across the pulldown coil within the relay with the multimeter. In the right photo, the fuse is OK, so the multimeter shows 0 Ω or Ohm. Now, we'll tackle the second-most common use of a multimeter in a car—measuring resistance and verifying continuity. In order that the multimeter does not alter the operation of the circuit when it is used to measure current, the resistance of the meter must be as low as possible. Photos show how to connect the ohm meter to the switch for testing. No continuity between smaller two terminals at any time (switch depressed or not). Coil on Plug: The Wired Differences 2011 ICAIA Fall Conference Ranken Technical College, St. Move the stalk to either the left directional on position or the right directional on position and test across the center and either of the outer prongs as pictured. First, you cannot simply connect a multimeter to the output of an SSR and measure the resistance when the input signal is applied. Insert the testing probes in the other end to complete the circuit, and then turn on the multimeter. Remove the fuse(s) you want to test. How Arduino Reads Temperature. To continue with your YouTube experience, please fill out the form below. To test fuses with this method, you will want the engine off and the key removed from the ignition. We have been receiving a large volume of requests from your network. A multimeter is a versatile tester that measures a variety of electrical properties, such as voltage, amperage, and resistance. To check a starter solenoid, you can use a digital multimeter and a few common tools. We have been receiving a large volume of requests from your network. How to Check and Replace Fuses Fuses stop excessive current flow that can overheat circuits, damage equipment, or cause a fire. If the gauge does not read at all, check the power with a multimeter at the gauge terminal. In order to check a dryer for no heat, here is a list of places to check. You might want to review the article on toggle switch wiring before proceeding. I was almost ready to call it a day and order a new motor assembly, but ran one other test with the dishwasher running and at a cycle where the motor should have been running. Checking the coils of a motor in permanent Delta connection. Another common problem is a bad relay. If the fuse is not good, replace it. There are no visual indicators to show that your relay is broken, but you can test if they still work by following this method. So now you know how to test a car fuse with a automotive multimeter. More Answers Below! Hey, if we didn’t answer you question yet, check the conversation board at the bottom of this page…lots of new answers and help there!. " jack of the multimeter; plug the BLACK test lead into the "COM" jack. If the relay is in good condition, multimeter. Measuring a fuse on board with an analog multimeter. Before staring the tests, be sure to thoroughly clean the part first, to eliminate any dust or carbon buildup that might have contributed to it's failure. Don’t worry, we will walk you through how to use a multimeter to troubleshoot your sensor and get it working properly in no time! But wait - what is a multimeter and how does it work? Let’s take a quick look. The easiest way to disable the ignition system will be to remove the relay or the fuse for the fuel pump. As such, swap an identical relay to the car horn relay. The test procedure is as follows. Then, move on to: 1. In the right photo, the fuse is OK, so the multimeter shows 0 Ω or Ohm. First, remove the thermocouple. Take the black ground lead of your multimeter and set it against the negative battery terminal. There are several ways to read temperature with an Arduino. You can check the ringing voltage with multimeter if you vat to make it to exactly right level. Go back to your Ohms setting. This is located in the main fuse box under the hood, and should be the largest fuse in there, making it easy to spot. Everything You Ever Wanted to Know About Capacitors Posted on March 30, 2012 by yorkcentraltechtalk What is a capacitor and why are they needed in a system and how do I check them out?. Touch one meter lead to the switch relay socket and the other to the battery negative post. If it's a lot less than 3 seconds, the cap is open. Test With Ohmmeter Testing with an ohm meter checking on a dryer These are the places that pass voltage to the heater elements on an electric dryer. Make sure that you read a resistance of near 0Ω. Pull one out and set it upside down somewhere. In this post I will complete guide you about how to test a refrigerator thermal overload protector using a multimeter. In heating and cooling these relay/contactors are used to turn on high voltage components such as motors, compressors, and other high voltage components. The Reed Relay Multiplexer can close a relay and make a measurement at a maximum rate of 300 channels per second. When the short is removed, it should take approximately 3 seconds to get within 4/5 of the supply voltage. While testing for clicks, check for closed or open connections across the contact points as applicable to the particular relay being tested. now the drawing of the circuit with the blade swith should either read open or no signal. If everything in the control panel appears to be working correctly to this point, use a voltmeter to (carefully) measure the two HOT connection points on the heating element receptacles on the bottom of the control panel. After all, we've got a sensor to troubleshoot. If you have a solid state relay and are wondering if its still good you might ask if it could be tested with a multimeter. The following steps can be used to perform the testing of the relay using a multimeter. Normally stamped into the plastic there will be a set of numbers. Determine relay number and pin out. Check the resistance value of Pt-100 to check / test if its okay. In the MGA 1500 car with the turn signal relay box, the first click you hear when the turn signal switch is activated will be the relay switching on, not the flasher unit. Re: How to check starter solenoid using multimeter. Checking a relay if its a bosch style relay as most are only takes a 9v battery and a Digital Multi Meter (DMM) or an Ohm Meter. Perform a cranking voltage test. Which pins do I need to bridge/apply power to in order to see if it is working. Place the multimeter one probe on NC terminal and other on COM terminal of Relay. How Arduino Reads Temperature. You use jumper wires. one with a needle display). If it’s a general purpose relay, look for the diagram on the relay body. To continue with your YouTube experience, please fill out the form below. 110-volt AC and 12-volt DC currents should be present as voltage inputs to the relay. The reading will show how much voltage is being lost. Since conventional ignition coils operate on 7 volts, the relay terminal supplies 12 volts to the ignition coil during. Normally a 3 phase supply is mentioned as R Y B. How to check a SCR with digital multimeter? Subramanian May 27, 2013 Power Electronics Testing 5 Comments SCR - Silicon Controlled Rectifier , Thyristor ( THYR atron and trans ISTOR ). Testing ABS relays w/ multimeter, How to? At some point during the month of August the Roadfly forums are going to become archive only. A relay has contact points that can go bad but can be tested. Check them. I want to test the female electrical connector to the lamp. A multimeter can be used to check how many amperes a household appliance is drawing to see if it is drawing excessive current, causing a circuit breaker to open. In this post I will complete guide you about how to test a refrigerator thermal overload protector using a multimeter. Perfect continuity (0 ohms). A diode is forward-biased when the positive (red) test lead is on the anode and the negative (black) test lead is on the cathode. To perform the test your solenoid, you would have to involve the multimeter. To test a relay to see whether it is good or defective, the simplest way to do would be to use a multimeter set to the ohmmeter setting and Part 2 -How to Bench Test a Ford Relay (Large Relay). In the case of a remote starter installation you should also listen to the engine to make sure that it is running properly. Connect 12 V supply to Control pins on the relay and listen for a physical click (Gross Test). The wire used in coils have fixed resistance in range of few 100's ohm. Wholesale and dealer pricing available on Multimeter Fluke. The only tool required to check a relay is a multimeter. If possible, secure the lead to the terminal by tucking it inside or underneath the clamping mechanism of the post. Turn on your multimeter and twist the selector knob to the nearest voltage scale higher than 12 volts. The meter indicates that the garage AC mains voltage is 120. The relays are located in the same fuse block and the fuses were. Knowing how to make a voltage measurement with a multimeter is a particularly useful skill and one which will be used time and again. The simplest way of finding this is to use a multimeter with an ohmmeter setting and then measuring the resistance values b. The display should now read one volt over the initial reading. If it isn't, check the ignition circuit. Do the test with a multimeter Electromechanical Relay EM. How to test an optocoupler posted in electro on June 28, 2011 - 47 Comments An optocoupler or optoisolator , is a device that contains a light-emitting diode ( LED ) and a photosensor ( photodetector, such as a photoresistor, a photodiode, a phototransistor, …etc ). So if you have only an multi meter without a big ammeter, go ahead and check resistance on pins of plug. Today I am writing about the refrigerator overload protector testing using multi meter. This accessory will allow the multimeter to measure starter current up to 1000 amps. You can test a fuse using either a digital volt-ohmmeter or an analog volt-ohmmeter. These are symptoms of a defective burner control switch. Remove the transistor from the circuit for accurate test results. 2014 · I cover 3. If the thermal fuse is blown, it will have to be replaced. Replace the light bulb if voltage is present and the light bulb is not lit; it may indicate a bad relay. 00 P B Pm 17ay 120 Power Relay Pm Series Socket Ac T137841 30 80a 300a - $42. I know one comes from the battery and the other goes to the starter. Power Relays Test Use this chart to identify the type of relay, then do the test listed for it. Re: [Electronics_101] How to test contactor coil You can not easily measure what the coil voltage is out of circuit. If the resistance value is around several MΩ , the NO terminal is working fine. How to Test a Spark Plug Wire: Video tutorial on how to test a spark plug wires. Testing The Normally Open (NO) Terminal of The Relay Put the multimeter in the ohmmeter setting. Placing test probes in A or mA inputs and then measuring voltage will create a short in the measurement circuit. Analog-type multimeters use a needle and printed scales to display results from a variety of electrical tests. Re: Starter relay multimeter test. Every fixer should know their way around a multimeter, which has just north of a zillion uses for testing electronic components and circuits. 5V reference voltages at TPS and mass air sensorSpeedo jumps to 80 when turning key to on. 2 Fluke Corporation Diagnosing voltage drop: electrical automotive troubleshooting 6. After all, the guide is titled, "How To Use a Multimeter to Test a Pool Pump Motor - Voltage". Dirk de Boer asks > > I have a question for the electronically inclined: Can you test a turn signal > flasher unit (say a Lucas three prong for an early MGB) on a bench using > a 12 V power supply and a multimeter? No, you test it using a 12 V power supply and a light bulb. A typical application would be to have an alarm on a door, with the switch mounted just above the. Leave the red meter lead on the base and move the black lead to the collector. Set the multimeter to the continuity setting. you should hear it in the cockpit of the car. Then use the Ohm scale on your multimeter to check. Check (listen) for the main relay clicking in when you turn on the switch. There is meant to be a 3 position toggle switch on my old Scimitar gear box but it is missing. Disconnect Relay. Today I am writing about the refrigerator overload protector testing using multi meter. 15A to 5 Ampere. The difference between a 4 and 5 pin relay is that a 4 pin relay is used to control a single circuit, whereas a 5 pin relay switches power between two circuits. There are other testing methods other than resistance that can be used. Set the function switch on your multimeter to the X1 Ohms range. The reading should be the same as the previous test. Procedure: Check the fuses with the meter. Is there a way to test my A/C compressor using a multimeter? My eyesight is really terrible even with my glasses, and I can't tell if it engages with the A/C on full blast. Relays are easy to test but often misunderstood. Put your voltmeter on DC volts in the 100 volt range. When you press the start button it should read zero volts across them, or maybe as high as. A quick look at how a car relay works and how to test them. Each set should read 0 ohms. To be able to switch the high current of the spindle motor I connected a solid state relay to the reed relay. If you test the thermocouple with the multimeter and you get a reading above 25, then you have another issue. When testing a solid-state relay, one has first to use an ohmmeter and check the relay across the NO (normally open) terminals once the control power is not working. Leave the red meter lead on the base and move the black lead to the collector. The easiest way to disable the ignition system will be to remove the relay or the fuse for the fuel pump. I know the connector has a high beam, low beam, & negative. A multimeter is a black box of electronic circuitry that allows you to troubleshoot just about any type of electrical wiring or. Products discounted daily so check back soon. The wire used in coils have fixed resistance in range of few 100's ohm. Learn more at flukeconnect. Check the connection bar for terminal (U, V, and W). The connections on the relay may not be tight. With the meter positive on the center terminal, the forward biased voltage drops were 0. This is kind of normal for electronic stuff. With motor current flowing, the TEST button can be used to check whether the relay is working correctly (device/solid-state TEST). Dirk de Boer asks > > I have a question for the electronically inclined: Can you test a turn signal > flasher unit (say a Lucas three prong for an early MGB) on a bench using > a 12 V power supply and a multimeter? No, you test it using a 12 V power supply and a light bulb. Ranges: DC and AC voltage, 500 volts, DC current, 0. Some manufacturers place a diagram and pin ID. If there is continuity, replace the relay. This means that the ability to write new posts and access various member features will go away. ) Fuel pump power relay – located under the driver’s seat in most stangs built before 92. Some manufacturers place a diagram and pin ID on the outside of the relay case to show which pins are part of the control circuit and which pins are part of the load circuit. In Electronics & Electrical systems, electrical wiring installations, maintenance, troubleshooting and repairing works. As you know that thermal overload protector is designed to protect the refrigerator compressor during over current flow. When testing for a wire which should have a positive polarity, you will need to do as follows. This means that the little wire enclosed in the mirror's glass is cut somewhere and stop the flow of current, preventing the wire to heat up, thus, no heated mirrors. Chevy Beretta, Cavalier, Corsica. Turn on the multimeter and set it to the diode-tester function, as directed by the instructions for your specific model. Photos show how to connect the ohm meter to the switch for testing. Touch one lead to one wire from the solenoid, the other lead to the other. Well I was so happy when I got 240v, I replaced the heat relay and got heat!! Thank You for your help!!. Set the multimeter to the continuity setting. By setting the selector switch to ohms and setting it on a lower range, you can test the resistance between the two points of the fuse. Let us see how to test an LED using a digital multimeter. We explain how a low voltage transformer is installed and wired, where the device is usually located, and how to test or troubleshoot & repair low voltage. To test if the fuse is blown, we require a multimeter. For extra credit, you can set a multimeter to measure conductivity (resistance) and connect it across relay terminals 30 and 87. If the fuse works, you need to check the connector. one with a needle display). Connect the A 1 (+) and A 2 (-) terminals to the multimeter according to the schematic. With your multimeter to Volts DC mode probe the wire that corresponds to the number 6 with the red multimeter test lead. The multimeter should have an infinite, or "OL," reading. the coily representation and the corresponding blades need to be tested and you should look for a reference number. Testing the Blower Resistor With a Multimeter. Look for 12 volts at the Pink/Black wire on the fuel pump relay. The final solenoid test. When a thermostat reaches a set temperature. On applications that have variable fan speed, the engine may also overheat if fan speed fails to increase when additional cooling is needed. Relay Wiring. We stock a full range of electrical testers ranging from 18th Edition testers & accessories to PAT testers and Part P electrical test meters. If your multimeter fails any. I assume that have a basic understanding of electrical systems and know how to measure voltage with a multimeter. For most reliable result, the input impedance of the meter should be 10 MOhm, or higher. The way that an automotive relay should be tested is to actually break out an automotive test meter and confirm proper operation of the relay. Test and Troubleshoot Relay: Older vacuums had a separate relay and transformer. Chevy Beretta, Cavalier, Corsica. Connect your black lead to chassis ground (-). Relays / Contactors are nothing more than a switch. Set the multimeter to the continuity setting. In the right photo, the fuse is OK, so the multimeter shows 0 Ω or Ohm. if not youll need a diagram of the blade positions and purpose. How can I test if PCM is good??These are the symptomscrank,no start. For the tester bulb to light there must be a good contact at the test points. With the vehicle warmed up and ECT triggering the PCM, there should be voltage at this red / orange wire. Place the multimeter selector in diode mode. It is very sensitive device. Test the circuit breaker with a voltage tester to see if it's faulty. Note the tacho in the background. A multimeter is a convenience. You will need an ohm meter to test the turn signal switch. In this post I explain how I test the inverter board in a laptop. The ammeter on the charger should jump to 20A to 25A, stay there for about 15 to 30 minutes and then drop off to about 6A to 10A. When testing relays it’s important to remember they’re not as complicated as they seem and neither is the test procedure. The multimeter, set to measure continuity, can be used in a similar way. Once configured, a multimeter can measure the resistance of the fuse element. Figure 15: Determine the common pin of the relay when the relay is activated. Without a scan tool capable of reading ABS codes, a visual inspection is the easiest thing to do when diagnosing an ABS light. Hp Multimeter In Stock | Martin Farm, Business & Industrial Equipment Supply Company. Multimeter used i. This article discusses how to test a switch with an ohm meter. A multimeter set to the Resistance mode (Ω) can be used as an additional diode test or, as mentioned previously, if a multimeter does not include the Diode Test mode.