Set the voltmeter to the correct DC or AC voltage range for the relay coil
Identify the relay coil terminals and the contact terminals
Measure the supply voltage at the relay coil terminals while the relay is energized
Check that the measured coil voltage matches the relay’s rated coil voltage
Measure the voltage across the coil when the relay is de-energized
If the relay is supposed to be on, verify that the coil is receiving voltage
If the coil is receiving correct voltage but the relay does not click, suspect a faulty relay
Measure voltage at the relay common terminal and normally open terminal
Energize the relay and check for voltage change across the switched contacts
Measure voltage at the normally closed terminal when the relay is de-energized
Compare readings to the relay’s expected contact behavior
Check for voltage drop across closed contacts while the relay is energized
If contact voltage readings are abnormal, suspect burned or stuck contacts
Remove power before testing resistance or continuity with the voltmeter
Confirm all readings against the relay’s wiring diagram or datasheet