How to Test a Solenoid Valve

Three isolated solenoid valves against a gray background.
  • 0-2 hours
  • Intermediate
  • 0-300
What You'll Need
Torch bulb
What You'll Need
Torch bulb

Solenoid valves are an essential part of any timed electronic water system. It allows water to pass through a particular tube, and it is therefore essential to the correct functioning of the system.

If you find that there is no water being sent to a particular area of your garden, or if you find that the plants in your greenhouse are not being watered, then a quick test of the valve should show you whether or not this is the cause of your problems.

Step 1 - Locate the Solenoid Valve

Remove the electronic water timer from the tap, and take off the back using a screwdriver. The solenoid valve will be inside, connected to both the timing mechanism and the inlet flow device.

It is made up of two parts: a coil of copper wire (which forms the solenoid), and a plastic plunger which is used to limit the flow of water (which forms the valve). You can leave this part in the timer, but you may need to remove the battery or power supply from the latter before you perform any kind of test.

Step 2 - Test With a Multimeter

The quickest way to test the solenoid valve is to apply a charge directly to it. There are two wires which cross directly above the valve as it lays in the timer that you will touch with a multimeter.

This should send a charge onto the valve, and if it is functioning normally, it will open. If you want to make sure that you are applying enough power to the valve, then you can take a lamp or torch bulb and hold it to the wires while the multimeter is supplying the power.

A sufficient charge will light the bulb. If the voltage is correct but the valve does not open, you will need to remove the whole solenoid valve and replace it.

Step 3 - Perform a Homemade Test

For those not lucky enough to possess a multimeter, there is another simple test you can perform using the bulb and a battery. Press the battery onto the wires which surround the solenoid valve, and then use the torch or lamp bulb to test that there is enough power going through. The bulb should light up, just as with the multimeter, and if the valve is working then it should also open.

You may also perform this test with an ohmmeter, checking for anything below 3.4 ohms or so.

How to Test a Solenoid Valve

How do you test a solenoid to see if it's good?

Connect a solenoid valve to an air supply, a gauge, and a power supply to test its functionality. Use air pressure on the valve's inlet port, connect the power supply to the valve terminals, and switch on the power supply.

Monitor the gauge pressure. The pressure should increase when the power is turned on and decrease when the power is turned off.

How do you test a solenoid with a multimeter?

To test a solenoid valve with a multimeter, turn on the solenoid valve's power supply.

Connect the red probe to the red post on the valve. Next, attach the black probe to the black post.

Do not allow these probes to touch at any point, or you could cause a short circuit.

Set the multimeter to resistance and listen. If you hear a tone, this will indicate that the solenoid valve is making a complete circuit when it is powered on.

The number on the display is the resistance in ohms. Change the dials to VAC to get a reading of the alternating current voltage.

How does a solenoid valve go bad?

Solenoid valves go bad for a number of reasons. Rust and wear over time alone can cause the valve to fail.

Irregular pressure, the wrong amount of electrical voltage being sent to the valve, and simple dirt in the engine can all cause this valve to fail to function properly.

Damage that results in some part of the valve becoming bent or otherwise damaged can also cause it to stop working.

What is the life expectancy of a solenoid?

On average, a solenoid valve will last one to three years before it needs to be replaced. With regular maintenance, however, the valve can last even longer.

Can a solenoid be bad and still click?

Solenoid valves, specifically the solenoid that powers them, can make a clicking noise even if the valve itself has gone bad. However, the same problem can occur with a dead battery.