Back to the Basics: The "Beep Test"

Many digital multimeters (DMM) have a diode/continutiy setting, often referred to as the "beep test".  This setting is designed to give an audible indication that a circuit is open or closed and, when combined with the Diode test, will display the voltage drop being measured.

While this beep test can have its benefits, never use it to make the determination that a circuit is acceptable  The setting can emit a beep even when the circuit has excessive resistance because it is designed to measure the voltage drop across a diode, where 0.7 VDC is perfectly acceptable.  If that reading was obtained while testing a main ground wire, the motor would be in for some serious trouble when under operation.

Only use the continuity setting to determine if you are on the correct ends of a wire, such as when you are trying to identify a wire within a boat harness where several of the same color may be present.  The diode setting should be used when attempting to determine if a diode is damaged or not, such as when testing a rectifier.

If you use the beep test to locate the correct end of a circuit, always follow up with either a resistance or a voltage drop test to ensure that the circuit is intact and undamaged.