Disconnect power to the solenoid
Identify the solenoid terminals
Inspect the solenoid for visible damage, corrosion, or burnt wiring
Check the coil resistance with a multimeter
Compare the resistance reading to the manufacturer specification
Test for continuity across the coil
Verify there is no continuity between the coil and the solenoid body unless specified
Apply the correct rated voltage to the solenoid briefly
Listen and feel for an audible click or movement
Check for proper plunger movement
Measure current draw during activation
Confirm the solenoid returns to its normal position when power is removed
Test the solenoid under load if applicable
Replace the solenoid if resistance, movement, or current readings are out of specification