Using voltage drop testing to diagnose a problem circuit

By ALLDATA Tech-Assist Team

Voltage drop testing is a simple but effective method of diagnosis to quickly locate high-resistance problems in a circuit. The DC voltage scale on a digital volt ohm meter (DVOM) or digital multi-meter can be used to measure the voltage drop across a load, device, or conductor.

Voltage drop is defined as the loss of voltage caused by the flow of current through resistance. Increased in resistance equals increases the voltage drop.

IMPORTANT NOTE: Whenever checking voltage drop, current must be flowing in the circuit.

Each load device (or component) must receive enough voltage to operate properly. The available voltage at a component should always be above that component’s minimum required voltage specification. If not, a loose connection, corrosion, or faulty power source is the problem. Open circuit problems such as broken or disconnected wires or connections can stop current flow. Even after fixing an open circuit, you should …

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