Your guide to multimeters & how they work

If you’ve ever found yourself staring at a multimeter, unsure of what all those buttons, dials, and symbols mean, you’re not alone. Whether you’re a seasoned DIYer or a total beginner, understanding the different functions of a multimeter is important for quickly determining what’s going wrong with your appliances. 

But we’ve got you covered! Let’s break down the key features of a multimeter so you can use them like a pro! And if you have any questions, don’t hesitate to ask us. If you find out that you need any replacement parts for your appliances while you’re troubleshooting, you can enter your model number at AppliancePartsPros.com to order them. Most orders arrive in just two business days, and we have thousands of free guides to show you how to install your new parts.

What is a multimeter?

A multimeter is a tool that allows you to measure electrical values like voltage, current, and resistance. It’s very useful for DIY repairs since it can show if there’s a problem with your appliances or electrical systems. You can use a multimeter to test different appliance parts to pinpoint exactly what’s wrong.

You can also use a multimeter to check batteries, diagnose issues in household wiring, and more. Multimeters have different settings for different tests, so you’ll need to know which one to use depending on what you’re checking.

What’s on a multimeter display?

When you first look at a multimeter, you’ll see a display section that shows the measurements. If you’re using a digital multimeter, it’ll show numbers and units. If you have an analog multimeter, you’ll see a needle pointing to different values.

Here’s what you’ll see and what it means:

• Voltage, current & resistance: The numbers you see on the display will tell you the value of what you’re testing, and the units will show whether it’s volts (V), amperes (A), or ohms (Ω).
• Current symbols: The display may also include symbols like a straight line for DC (direct current) and a wavy line for AC (alternating current) so you know what type of signal you’re measuring
• Other readings: If you’re testing things such as a diode or continuity, then the display will show relevant information to confirm if the part is working or if there’s a problem.

Read more: How To Use A Multimeter To Check Appliance Parts

Multimeter functions & what they’re used for

There are several tests you can perform with a multimeter. Here’s what you should know about them.

Voltage (V) testing

AC voltage (alternating current) is what powers most household appliances. When you set your multimeter to AC voltage (usually indicated by a “V~”), you can check things like wall receptacles, power cords and the voltage intake of the appliance itself.

DC voltage (direct current) is found in things like batteries, motors and small electronics. You’ll have to set your multimeter to DC voltage (usually indicated by a “V—”) when you’re testing those items.

Important: You should always start with the highest voltage setting to avoid damaging the meter and be sure to safely place the probes on the correct contacts (red probe to positive, black probe to negative).

Current (A) testing

Current measurement lets you test how much electricity is flowing through a wire or part. This function is usually reserved for more advanced repairs.

To measure current, you’ll need to break the circuit open so the multimeter can be placed in series with the device. This means that the current would be forced to flow through the multimeter.

Important: Always set the multimeter to the correct range for amperage and never try to measure current without disconnecting power first as it could damage the meter or cause serious injuries. 

Resistance (Ω) testing

Resistance testing is useful for checking whether a part like a resistor, wire, or fuse is still good. A higher resistance typically means the part isn’t conducting electricity properly.

To test, you’ll set your multimeter to resistance mode (Ω symbol), and connect the probes across the part you’re testing.

If the reading shows zero or close to zero, then the part is likely shorted (bad). If the meter shows a very high number or infinite resistance, then the part could be broken or disconnected.

Continuity testing

Continuity testing helps you identify whether there’s an electrical path or break in a circuit. It’s a quick way to find faulty wires or connections.

In continuity mode, your multimeter will usually make a beeping sound if the circuit is complete (i.e., the wire or part isn’t broken). No beep means there’s an open circuit or a break in the wire or part.

Diode testing

When testing diodes, your multimeter will check if the diode is allowing current to flow in one direction and blocking it in the other.

To perform this test, you’ll set your multimeter to the diode test function ( marked with a diode symbol), and place the probes on the diode.

The multimeter should show a voltage drop (typically 0.7V for silicon diodes) in one direction, and no reading in the opposite direction. If it doesn’t behave like that, then the diode is faulty.

Read more: Tool Maintenance 101: The Basics You Need To Know

Common situations for multimeter testing

Now that you’re more familiar with how to use a multimeter, let’s dive into some common DIY repairs where it’ll come in handy.

Check batteries and power supplies

One of the simplest uses for a multimeter is testing batteries to see if they’re good or if they should be replaced.

1. Set your multimeter to DC voltage mode (V—) and place the probes on the battery terminals.
2. Check the meter reading. A good 1.5V battery should read about 1.5 volts, and a 9V battery should read close to 9 volts.
3. If you’re testing a power supply, check the output voltage to make sure it matches the required specifications.

Troubleshoot electrical systems in household appliances

If an appliance such as a dryer or dishwasher isn’t working, a multimeter can help you figure out where the issue lies. You can use it to check the power supply, internal wiring, and individual parts like thermostats or switches.

1. Test the power input to the appliance. If there’s no voltage where it should be, then you’ll need to check the power cord, fuse, or circuit breaker.
2. If power is coming through, use the continuity mode to check individual parts like switches, motors, or heating elements. A lack of continuity in any of these parts means they’re faulty and need to be replaced.

Test fuses, wires, and switches

You can use a multimeter to check the condition of fuses, wiring, and switches.

1. Use the continuity setting to test fuses. If the multimeter beeps, the fuse is good; if it doesn’t beep, it’s blown and needs to be replaced.
2. You can check if switches are functioning properly by measuring the continuity when they’re turned on and off.

Important: When testing wires, use continuity mode to make sure there are no breaks or shorts. This is especially useful if you suspect a wire is damaged but can’t see it.

Read more: Must-Have Tools for Appliance Repair – DIY For Beginners

More help is here

Thanks for reading! We hope this guide helped you learn more about multimeters! If you need some replacement parts or help with troubleshooting, grab your model number and head over to AppliancePartsPros.com. We have over two million parts in stock and most orders arrive in just two business days. If you need some help with finding the right part or placing an order, you can contact our team at 1 (877) 477-7278.

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