Locate the solenoid on the water valve.
Unscrew the plunger from the valve by turning the solenoid counterclockwise.
Remove any dirt or debris from inside the plunger well. Insert the solenoid and test the unit.
Remove the wires from the solenoid unit by pulling on the connectors.
Set a voltmeter, a unit used for the testing of electrical voltage, to the ohms setting.
Touch one probe to each of the solenoid wire connectors. You should receive a reading of 20 to 60 ohms. Anything over or under requires you replace the solenoid.