This test already assumes the existence of an open in the circuit and it is used to help locate the open portion.
- Isolate the circuit from power and ground.
- Connect the self-powered test light or ohmmeter ground clip to the ground side of the circuit and probe sections of the circuit sequentially.
- If the light is out or there is infinite resistance, the open is between the probe and the circuit ground.
- If the light is on or the meter shows continuity, the open is between the probe and the end of the circuit toward the power source.