How to test an open circuit in a closed circuit
An open circuit has a break in a wire and prevent current flowing through a circuit.
Voltmeter or a Multimeter
Step # 1 Use an ohmmeter or a multi meter. A volt meter only read voltages and a multi meter reads ohms, amps, voltage etc…Set the multi meter to ohm setting. A “1” represent an open circuit and a “0” (zero) represent a closed circuit.
Step #2 Locate on the vehicle wires where the fault may be. Use a pin or a needle and probe the wires at each part of the wires.
Step #3 Use the negative lead of the multi meter and touch one end of the pin, and the positive lead at the other end.
Step #4 Now you should get a reading. A reading of “1” is an open circuit and a reading of “0” is a closed circuit.