How To Use A Multimeter

Step 1 Testing Continuity

• A continuity test tells us whether two things are electrically connected: if something is continuous, an electric current can flow freely from one end to the other.
• If there's no continuity, it means there is a break somewhere in the circuit. This could indicate anything from a blown fuse or bad solder joint to an incorrectly wired circuit.
• Continuity is one of the most useful tests for electronics repair.
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Step 2




• To begin, make sure no current is running through the circuit or component you want to test. Switch it off, unplug it from the wall, and remove any batteries.
• Plug the black probe into the COM port on your multimeter.
• Plug the red probe into the port labeled with a V symbol (in this case, the right port).
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Why do we need to make sure that no current is running through the circuit?
When there is another parallel branch with 24VDC power and 4-20mA output, the value of the resistance measured comes as zero. Whats the reason?
Fraz - Jun 2, 2017 Reply
The way that a meter measures resistance is by sending a small current across the probes and then measuring the resulting voltage. So, another current will disturb your digital multimeter's (DMM) reading.
nicO - Feb 1, 2023
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Step 3
• Switch on your multimeter, and set the dial to continuity mode (indicated by an icon that looks like a sound wave).
• Not all multimeters have a dedicated continuity mode. If yours doesn’t, that’s okay! Skip to step 6 for an alternate way to perform a continuity test.
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I want to search the resistance of gold and see if I have some
Joel Stegner - Sep 8, 2016 Reply
What does a sound wave look like?
Greg Janssen - Mar 15, 2018 Reply
Gold is highly conductive near zero resistance which is why they use it in conducters. Use "specific gravity" type tests or "mass spectromatry" type tests for elements.
Sound looks like sine waves with various amplitudes and cycles per unit of time.
MidnightWolf - Apr 4, 2023 Reply
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Step 4
• The multimeter tests continuity by sending a little current through one probe, and checking whether the other probe receives it.
• If the probes are connected—either by a continuous circuit, or by touching each other directly—the test current flows through. The screen displays a value of zero (or near zero), and the multimeter beeps. Continuity!
• If the test current isn't detected, it means there's no continuity. The screen will display 1 or OL (open loop).
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Step 5
• To complete your continuity test, place one probe at each end of the circuit or component you want to test.
• As before, if your circuit is continuous, the screen displays a value of zero (or near zero), and the multimeter beeps.
• If the screen displays 1 or OL (open loop), there's no continuity—that is, there's no path for electric current to flow from one probe to the other.
• Continuity is non-directional, meaning it doesn't matter which probe goes where. But there are exceptions—for instance, if there's a diode in your circuit. A diode is like a one-way valve for electricity, meaning it will show continuity in one direction, but not in the other.
• To check for this, reverse what the probes are touching and check for continuity. If the multimeter shows continuity, then it's possibly a diode.
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Step 6 Test for continuity (alternate method)
• If your multimeter doesn't have a dedicated continuity test mode, you can still perform a continuity test.
• Turn the dial to the resistance mode.
• If your multimeter has manual ranging, set the resistance to the lowest setting.
• Resistance is measured in ohms, indicated by the symbol Ω.
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Step 7
• In this mode, the multimeter sends a little current through one probe, and measures what (if anything) is received by the other probe.
• If the probes are connected—either by a continuous circuit, or by touching each other directly—the test current flows through. The screen displays a value of zero (or near zero—in this case, 0.8). Very low resistance is another way of saying that we have continuity.
• If no current is detected, it means there's no continuity. The screen will display 1 or OL (open loop).
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You mentioned that if your meter screen displays 1 or OL
But what happen if it shows other numbers
Like 5.5 or somewhat?
ddplc - Oct 8, 2019 Reply
It means you have current flowing which would indicate a good path or circuit. Also means you have a power supply connected which I think was mentioned earlier in the article to disconnect all power supplied, as in a.c., d.c. Especially in a vehicle as running tests on computer module circuits with the vehicle battery connected can damage a computer module circuit..
Henry DeVito - Jan 30, 2021 Reply
I'm very pleased to have discovered these directions. Interestingly, I tried the two probes on different sections of a screwdriver – resistance showed very high. Is that possibly because of chrome coating on the screwdriver?
James O'Neil - Jan 27, 2023 Reply
May not be a chrome coating at all even if it looks like it. The screw drivers "resistence" is the result of what alloys are used in the shank of the screw driver ... ie ... tin, zinc, carbon, etc.
MidnightWolf - Apr 4, 2023 Reply
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Step 8
• To complete your continuity test, place one probe at each end of the circuit or component you want to test.
• It doesn't matter which probe goes where; continuity is non-directional.
• As before, if your circuit is continuous, the screen displays a value of zero (or near zero).
• If the screen displays 1 or OL (open loop), there's no continuity—that is, there's no path for electric current to flow from one probe to the other.
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What does it mean when I first get 1 then the meter jumps to all kinds of numbers and there is no beeping?
Choymae Huie - Mar 29, 2018 Reply
Most likely you have bad contact with whatever you are measuring.
MidnightWolf - Apr 4, 2023 Reply
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Step 9 Measuring voltage
• The next four steps will show you how to measure voltage.
• Plug the black probe into the COM port on your multimeter.
• Plug the red probe into the port labeled with a V symbol (in this case, the right port).
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Step 10
• Switch on your multimeter, and set the dial to DC voltage mode (indicated by a V with a straight line, or the symbol ⎓).
• Virtually all consumer electronic devices run on DC voltage. AC voltage—the kind that runs through the lines to your house—is considerably more dangerous, and beyond the scope of this guide.
• Your multimeter may be auto-ranging or manual ranging. An auto-ranging multimeter (such as the iFixit multimeter) will automatically determine the best measuring range. All you have to do is set what kind of measurement you want to take.
• If your multimeter is manual ranging, you'll also need to set the correct range for the voltage you expect to measure.
• Each setting on the dial lists the maximum voltage it can measure. So for example, if you expect to measure more than 2 volts but less than 20, use the 20 volt setting.
• If you're not sure, start with the highest setting.
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Step 11 Auto-ranging voltage measurement
• If your multimeter is manual ranging, skip to the next step.
• Place the red probe on the positive terminal, and the black probe on the negative terminal. The multimeter will display the measured voltage.
• Reversing the probes won't do any harm; it just gives a negative reading.
• Skip the next step, which describes how to measure voltage using manual ranging multimeters.
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Step 12 Manual ranging voltage measurement
• Follow this step to measure voltage with a manual ranging multimeter.
• Place the red probe on the positive terminal, and the black probe on the negative terminal.
• If your range was set too high, you may not get a very precise reading. Here the multimeter reads 9 volts. That's fine, but we can turn the dial to a lower range to get a more precise.
• If you set the range too low, the multimeter simply reads 1 or OL, indicating that it is overloaded or out of range. This won't hurt the multimeter, but we need to set the dial to a higher range.
• With the range set correctly, we get a reading of 9.42 volts.
• Reversing the probes won't do any harm; it just gives us a negative reading.
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Step 13 Measuring resistance
• The next three steps will show you how to measure resistance with your multimeter.
• To begin, make sure no current is running through the circuit or component you want to measure. Switch it off, unplug it from the wall, and remove any batteries.
• Remember that you'll be measuring the resistance of the entire circuit. If you want to measure an individual component such as a resistor, measure it by itself—not with it soldered in place!
• Plug the black probe into the COM port on your multimeter.
• Plug the red probe into the port labeled with an Ω symbol (in this case, the right port).
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Be careful when testing ohms on the circuit board, the best test is to remove the part so you are only testing the part not the circuit around the part. Transistors, resistors, caps need to be removed or at best one leg of the part. One time I had a burn open resistor, then I tested the resistor with my Ohms test I got some resistor reading. This was caused by back feed in the circuit.
John E Reese - May 18, 2021 Reply
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Step 14
• Switch on your multimeter, and set the dial to resistance mode.
• Resistance is measured in ohms, indicated by the Ω symbol.
• The iFixit multimeter is auto-ranging, meaning it will automatically determine the best measuring range.
• If your multimeter is manual ranging, you will need to set the correct range for the resistance you expect to measure. If you're not sure, start with the highest setting.
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Step 15
• Place one probe at each end of the circuit or component you want to measure.
• It doesn't matter which probe goes where; resistance is non-directional.
• If your multimeter is manual ranging:
• If your multimeter reads close to zero, the range is set too high for a good measurement. Turn the dial to a lower resistance range.
• If you set the range too low, the multimeter simply reads 1 or OL, indicating that it is overloaded or out of range. This won't hurt the multimeter, but we need to set the dial to a higher range.
• The other possibility is that the circuit or component you are measuring doesn't have continuity—that is, it has infinite resistance. A non continuous circuit will always read 1 or OL on a resistance test.
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