Electrical tests are easy once you know how and when to use a multimeter.
Select the appropriate function.
Make sure the device is unplugged and the switch is ON.
Connect the multimeter's probes to the device.
A multimeter tests electrical continuity. It also can measure the amount of alternating current (AC or household current) or direct current (DC or battery current) in a plugged-in or live circuit. It can check voltage, too. For example, a multimeter can verify that there are about 120 volts in an AC circuit or that a 9-volt battery is fully charged. In addition, a multimeter can check resistance. A continuity tester checks resistance, but answers YES or NO. A multimeter checks resistance and reports how many ohms (the measurement of resistance) a circuit has.
Multimeters are relatively inexpensive. Multimeters are available in digital and analog models. Digital multimeters will display readings in numbers. Analog multimeters indicate values with a needle over a scale.
The analog unit shown was $10 and the digital multimeter was $20, though you can pay $50 or more for more accurate models. The ones used in this book are sufficient for most electrical tests.
You can use a multimeter to test motors, switches, controllers, and many other electrical gadgets. Specific instructions will come with the multimeter (also called a volt-ohmmeter or VOM) you purchase.
Here's how to use a multimeter to test an electric appliance:
Disconnect the cord from the power source, except when testing a live circuit.
Plug the test leads in to the multimeter.
Select the function (ACV, DVC, RESISTANCE) and the range (maximum reading expected).
Connect the probes to the cord or appliance component.
Interpret the reading. The Fix-It Guides and the device's owner's manual will tell you what to expectand what to do about it.