Continuity/Resistance/Diode

This group of settings on a multimeter allow you to accurately test for continuity and determine the resistance of many vehicle components.

Continuity
To check for continuity in a circuit use the lowest ohm scale available. Place the leads of the multimeter on each end of the circuit or component being tested. A reading of less than one ohm indicates acceptable continuity.

Resistance
To test for resistance values, place the leads of the multimeter on each side of the circuit or component being tested. Adjust the ohm settings on the multimeter until an acceptable reading is displayed. The lowest scale that gives a reading without going over the range (1 or OL) gives the most accurate reading. Compare the reading displayed on the multimeter to the specification found in the service manual or bulletin. Verify that the scale reading on the multimeter is the same as in the specification (megohms, kilo-ohms or ohms).

NOTICE: when using a multimeter on the ohmmeter or diode test scale, make sure the circuit or component is disconnected from a power source. Applying voltage to a multimeter when you are measuring resistance can damage the multimeter.

Diode Testing
Most digital multimeters have a Diode setting. This setting is used to test a diode to verify current flows in only one direction.

A good diode will display between 0.4 and 0.8 volt on the meter when the leads are forward biasing the diode, this indicates the diode is allowing current to flow in that direction. When the leads are reversed, the meter should read 1 or 0L, indicating the diode is blocking the flow of current in the opposite direction. This indicates a good diode. If the diode allows current flow in both directions or prevents current flow in both directions, the diode is damaged and should be replaced.