Continuity Test
Checking with the ohm or buzzer range whether a conductive path exists between two points in a de-energised circuit. It quickly finds complete interruptions such as a broken core or a blown fuse, but it usually hides a bad, high-resistance connection.
A multimeter sends a very small current in the continuity range. An oxidised or loosened connection can pass this small current and the instrument gives a good result; the same connection can collapse under 20 A. This is the most important limitation of the test.
- Rule of use: the circuit must be de-energised, and if possible the line disconnected at both ends. Otherwise misleading continuity is read through parallel paths.
- Expected value: on a short, sound core the reading is typically below 1 ohm. Measure the resistance of the probe leads themselves and subtract it from the result.
- Where it is sufficient: fuse checks, connector pin mapping, searching for a broken core, verifying a button contact.
- Where it is insufficient: a connection that heats up, voltage that sags under load, suspicion of intermittent contact.
The order in field diagnosis is therefore this: eliminate gross interruptions with continuity, then assess connection quality by measuring the voltage drop under real load.
Context in which this term is used: DC motor and driver fault diagnosis matrix