Are Lawn Mower Solenoids Universal? – Answered

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A solenoid is a device that interacts with the starter motor and plays a role in turning on the engine. If your lawn mower refuses to start and there is no clicking sound, the solenoid is probably damaged and needs to be replaced. But can you choose just any type of solenoid?

Lawn mower solenoids are not universal. If you have to replace the solenoid, check if it is a 3-post or a 4-post and make sure the replacement is the exact type. Using the wrong one can damage your lawn mower.

Why Solenoids are Not Interchangeable

Lawn mowers typically use 3-post or 4-post solenoids. Sometimes the solenoid is on the starter mount, and in others it is closer to the battery. Some mower solenoid designs include voltage and lighting, but others do not. There are round solenoids and there are square ones too.

Lawn mowers use different schematics for solenoids. If you install the wrong one it will cause all kinds of problems. Is it possible to replace a 3-post lawn mower solenoid with a 4-post? Yes. But it could void the mower warranty. If you make a mistake this could damage the system. If you are going to replace the solenoid, it is best to get a product that is exactly like the old one.

Starter solenoids serve similar purposes in lawn mowers, though some have extra features. Because manufacturers have proprietary designs, you cannot us just any type. If you have to get a new, make sure the component will work with your mower.

If your lawn mower does not start, there are many possible reasons for this. A faulty solenoid is one of them. Knowing what the symptoms are is essential so you can take the right approach.

In the following sections w will explain how to test a solenoid and also how to replace them. If your tests show this is necessary, it is crucial that you learn what type of solenoid must be used. That is why we had to explain in this post what a solenoid does for your lawn mower.

How to Test a Lawn Mower Solenoid

Usually we only test a solenoid if there is something wrong with the lawn mower. Here are the most common signs of a bad solenoid. If one or more of these symptoms appear, you should check the solenoid right away.

Signs of a damaged solenoid

  • Engine does not start
  • No clicking sound when engaging the engine
  • The flywheel is not engaged by the starter
  • Engine does not crank or does so slowly

If you notice any of these symptoms, a test is in order.

Required Tools

  • Multimeter (the AstroAI Digital Multimeter does the job really well)
  • Wrenches
  • Screwdriver
  • Light (Porter Cable work lights for additional illumination)

Step 1

Charge your mower battery to full power. Use a multimeter to check if the battery has at least 12 volts. Now turn your mower off and take out the key.

Step 2

Find the solenoid, usually it is near the battery. Check your owner’s manual to be sure. In some cases you have to raise the seat and remove the positive and negative terminals off the battery.

Next you have to take out the battery out of the mower. This might require removing some tabs or switches depending on your mower model.

Look for two cables. On is from the cable to the starter and the other from the cable to the battery. Place the screwdriver over the solenoid so that it makes contact with the wires. It is normal for the plug to spark when you do this.

What you have done is bypass the solenoid. If the engine runs, it means the solenoid is broken and must be replaced. Before replacing, make sure the grounding and cables are properly set.

Step 3

If the solenoid is on the starter mount, remove it from the starter. Now you can use a battery charger to verify the status of the solenoid.

Once you have detached the starter solenoid, connect the positive clamp to the solenoid exciter wire and the large post. Next, click the negative clamp to the starter.

This is also a good time to examine the solenoid and find out why it is not working. There are many reasons this can happen such as wear and tear, moisture, corrosion or a faulty metal plate.

How to Replace a Lawn Mower Solenoid

If your tests indicate the solenoid is broken, you have to purchase a new one. The most important thing is to check if the solenoid is 3-post or 4-post. You can look in the owner’s manual or the manufacturer website for the specific type of solenoid you must buy.

If you plan to use lawn mower gas with your car you have to use the right gas. This rule also applies to solenoids, as using the wrong can be disaster.

Once you have a new solenoid, installation is a straightforward process. It is however, still a good idea to have your lawn mower manual on standby. This is because lawn mowers have different designs and configurations. Even so, the basic process is the same.

Step 1

Remove the old solenoid. You use the same steps you did earlier during testing. Ensure the ignition switch is off. Take out the key if you have not already done so.

Step 2

Set the mounting clip that is on the old solenoid onto the new one. Position the mounting clip onto the mower. Fasten the mounting bolts and connect the wires. Use the nuts to connect the terminals and the wires.

Step 3

Put the mower battery box back into its original location, right where you took it off earlier. Set the tabs and reattach the seat switch clip on the bracket.

Bring the battery box down and configure the wires accordingly. Plug the positive cable to the positive terminal and plug the negative cable to the negative terminal. Put the cover on and you are don.

Return the key, turn the mower on and it will run like new. If you followed the instructions here, the mow will run fine. If it does not, check the connections and wiring. The might be a few loose screws or cables.

Related Questions

Can you bypass a lawn mower solenoid?

Yes, just place a screwdriver or needle nose pliers across the metal contacts of the solenoid. This will bypass it completely. If you turn the engine and it is working, there is a problem with the solenoid and must be replaced.

What is the right way to wire solenoids?

Just make sure the terminals touch and it should be fine. As long as the wires are not frayed the set up will work.

I just replaced the solenoid and now it is no longer working. Why?

There could be a problem with the wiring. Check if the wires are properly connected. There could also be other problems with the engine that are not related to the solenoid.

How long will a solenoid last?

Typically a solenoid is good for at least 3 years. A lot of factors determine its longevity such as the lawn mower design, how often it is used and maintenance.

Why do mower solenoids fail?

It can be due to wear and tear. Using the wrong voltage can cause damage. Sudden electrical spikes or misuse of the lawn mower are also likely casus.

If my lawn mower refuses to start, does that mean the solenoid is damaged?

There are many reasons why a lawn mower may refuse to start. There could be issues with the fuel, the spark plug, carburetor etc. If there is smoke the problem is likely fuel related. But if you do not hear a clicking sound it is likely due to the solenoid.

What happens if the wrong type of solenoid is installed?

It depends. If you have a round solenoid and you bought a square one, you may not even get it to fit in the system. If you bought a 3-post while the required one is a 4-post, it could damage the mower. This is why you should take steps to ensure you are using the right type.