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How to Tell Your Toro Starter Solenoid Bad (Troubleshoot)

When you try to start your Toro riding mower or zero-turn, all you hear is a clicking or humming sound and nothing happens. You can’t get it to turn over the engine.

This is often what you hear when the starter solenoid is bad and no longer getting power to the starter.

Keep reading and I’ll go over where to find the starter solenoid and how to determine whether it is good or bad.

Lawn mower starter solenoid

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Follow all safety instructions provided in your equipment operator’s manual before diagnosing, repairing, or operating. Consult a professional if you don’t have the skills, or knowledge or are not in the condition to perform the repair safely.

What Is a Toro Starter Solenoid? 

A Toro starter solenoid is an on/off switch of sorts. It is an electromagnet switch that is actuated to engage the starter motor to turn your engine over. 

The solenoid is often found mounted on the starter. However, it does not have to be mounted on the starter to do its job. 

You may have the solenoid mounted on the frame closer to the battery than the starter.

Three & Four Post Solenoids 

This is a typical wire schematic of three and four-post solenoids. Remember, not all wire schematics are the same for every lawn mower.

Some schematics will include wiring for options like lights and 12-volt ports. These diagrams only show the basic wiring schematic. 

How to Identify Your Toro Starter Solenoid? 

You will find solenoids on every electric start engine. Your solenoid may be round or square in shape with either 3 or 4 posts sticking out of it.

You will find some solenoids attached to the top of the starter and others may be attached to the mower’s frame.

The positive (+) wire from the battery attaches to one side of the solenoid. Following the positive wire of the battery is an easy way to find your solenoid. 

What Causes a Toro Starter Solenoid to Go Bad? 

A solenoid is an electrical switch. As we all know, an electrical item can fail at any time.  

Inside the solenoid, you will find a spring and copper plate. A Toro starter solenoid can go bad if the spring gets weak or the copper plate starts to corrode.

The solenoid can also fail as a result of a weak starter, bad battery, or bad ground.  

Symptoms of a Bad Toro Starting Solenoid

A Toro starter solenoid may be bad when you hear a click or hum when you turn the ignition key and your mower doesn’t start.

Another indication your solenoid may be bad is when a wire gets hot and begins to smoke or melt

Steps to Diagnose a Bad Toro Starter Solenoid 

List Tools Needed: 

  • Volt-Ohms Meter 
  • Screwdriver 
  • Continuity Light
  • Wrenches to check for loose wires 
  • Needle Nose Pliers (If screwdriver does not work) 
  • Battery Charger (Optional) 

If you are going to diagnose the solenoid on your lawn mower, there are a few ways to do so. 

1. Make Sure Your Battery Has a Full Charge

Use your voltmeter to make sure your battery has at least 12.3 volts in it. Read more about testing your battery in our article “5 Things That Are Draining the Life of Your Lawn Mower Battery“.

2. Get Your Mower Ready to Start

  • Set the parking brake
  • Make sure your lawn mower is in neutral
  • Turn the key to the on position

3. Bypass the Starter Solenoid Using a Screwdriver

Lay a long screwdriver over the solenoid to touch the two cables to bypass the starter. The two cables you are looking for are the cable from the battery and the cable to the starter.

It may throw a spark when the screwdriver makes contact with the wires. This is common so don’t be alarmed.

If the engine happens to turn over while you have your solenoid bypassed there is a good chance your solenoid is bad. If the screwdriver does not work well, you can also use needle nose pliers to jump the solenoid. 
You may only have loose wires or bad ground so you will need to check these items out before you replace the solenoid. 

4. Test the Solenoid

Starter solenoids that are mounted on the starter can be tested. Remove the starter from the engine and test the solenoid with a battery charger. This is a good way to watch if the starter is working with the solenoid. 
Once the starter has been removed from your lawn mower, you need to attach the negative (-) clamp to the case of the starter and touch the positive (+) clamp to the big post and exciter wire on the solenoid. This is just a quick bench test when the starter is out. 

Can You Bypass a Toro Lawn Mower Starter Solenoid? 

A lawn mower solenoid can be bypassed by placing a long screwdriver across the solenoid by touching the cable from the battery to the cable to the starter. Be careful. The connection could cause a spark which is normal.  

If you’re not getting sufficient power to the solenoid to engage the starter, there are several other items to check. These include the battery and loose or corroded cables.

Check out this article for additional items that can cause your Toro to click and not start.

Still Having Problems with Your Toro Lawn Mower?

It would be great to own a problem-free lawn mower, but it’s never the case. No matter what brand mower you own, you’re going to run into problems the longer you own it.

To help you troubleshoot your mower problems, I have put together a list of common problems along with causes and solutions to fix them. Check out Common Toro Lawn Mower Problems and Solutions to learn more.