Operation CHARM: Car repair manuals for everyone.

Testing For Voltage Drop




This test checks for voltage drop along a wire, or through a connection or switch.
1. Connect the positive lead of a voltmeter to the end of the wire (or to the side of the connector or switch) closest to the battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connector or switch).
3. Operate the circuit.
4. The voltmeter will show the difference in voltage between the two points. A difference, or drop of more than 0.5 Volts may indicate a problem. Check the circuit for loose or dirty connections.