Lawn mower starting circuit. Can You Overcharge a Lawn Mower Battery? Why This Is Bad

Can You Overcharge a Lawn Mower Battery? Why This Is Bad

The question “Can you overcharge a lawn mower battery?” is a common one among gardeners, and the answer to this conundrum is that it is not only possible but a recurrent problem we face on behalf of lawn mower owners.

People who rely on cheap chargers that continue automatically and are not voltage controlled eventually end up decreasing their lawn mower’s battery life or damaging it altogether. Our team discusses this problem in detail and how to prevent overcharging batteries.

• Is It Possible to Overcharge Your Lawn Mower Battery?

• – Overcharging Releases Toxic Gases
• – Temperature of the Battery Will Increase
• – The Battery’s Capacity Will Decrease
• – Overcharging Is Potentially Dangerous

• 1. Invest in Automatic Chargers
• 2. Build a Circuit That Prevents Overcharge
• 3. Keep a Close Eye on the Battery While It Charges
• 4. Go for a Voltage Regulator

• 1. Follow Important Safety Precautions First
• 2. Find Out Where the Lawn Mower Battery Is Located
• 3. Use a 12-Volt Battery Charger
• 4. Connect the Charger and the Battery
• 5. Keep the Battery Plugged in Until Charged
• 6. Unplug the Charger

Is It Possible to Overcharge Your Lawn Mower Battery?

Yes, it is possible to overcharge your lawn mower battery, so you will need to charge with more care. Older lead-acid batteries are easily damaged by overcharging, whereas rechargeable lithium-ion mower batteries are slightly better tolerant of overcharging but will still acquire damage.

Overcharging is when the charger doesn’t stop on its own once the battery has reached 100 percent charged. That is why we are such vocal advocates of going for automatic chargers that stop the outflow of electricity to the battery once its charging is complete.

Chances are that most of you are still using any old regular charger for your batteries of lawn mowers. The charging time varies according to the size of the battery and the amperes of these trickle chargers.

Keep an eye on when the mower becomes fully charged to turn the charger off. Cheap and fast type of chargers also ends up overcharging the batteries. It is very easy to overestimate how much time it could take to recharge the battery.

Here are some effects of overcharging on your lawn mower’s health and lifespan.

– Overcharging Releases Toxic Gases

Lawnmower batteries, when overcharged, release toxic gases that are not good for anyone. In the lead acid type of batteries, this can have life-threatening consequences. These batteries produce hydrogen gas when overcharged, which can cause an explosion in case of poor ventilation.

In other cases, sulfide gas might be produced within the battery. You can easily smell this gas being produced because of its nasty rotten eggs smell. It would significantly make you sick and even be fatal in large quantities.

– Temperature of the Battery Will Increase

Rising temperature is one of the best indicators that your battery has been overcharged. Every time you overcharge, the battery will become hotter quicker than before. There comes the point when the temperatures within the battery will rise to such an extent that it causes some pretty serious damage.

This is called a thermal runway and must be avoided at all costs. Once the battery reaches the point of the thermal runway, there is no way to stop it from heating more and more. On a very basic level, a runaway is a chemical reaction that sustains itself and is difficult to control.

Overheated lead acid batteries face another major problem. The battery needs water mixed with sulfuric acid to work, and this water begins to evaporate when the temperature within the battery rise. Most batteries do not have adequate ventilation to release these vapors. As a result, intense pressure will develop in the battery, and it might begin to swell.

– The Battery’s Capacity Will Decrease

Occasionally overcharging lawn mower batteries to a few volts higher than normal is not that big of a deal. Modern batteries have been designed to withstand slightly higher voltages without much deterioration. For example, a typical 12-volt battery will typically be able to store a charge of upto 14 volts with no problem at all.

Still, it would be best to not make overcharging a long-term habit. When repeatedly overcharged, batteries slowly lose their capacity to hold a charge. You will see that the battery starts to drop sooner than before and needs more frequent recharges. This is true whether you have a lead-acid or a lithium-ion battery running your mower.

– Overcharging Is Potentially Dangerous

Habitual overcharging lawnmowers will eventually destroy their batteries. The continual rise in temperature, discharge of toxic gases, and the breakdown of battery parts will eventually cause it to start swelling and bulging.

If your battery seems to be swelling, this means that it has already begun to break down from within. Some mower batteries start leaking fluids instead of bulging outwards. Only lead-acid battery types tend to leak fluids when distressed. Be extremely cautious when dealing with this because the leaking fluid is acid. Don on your thickest rubber gloves and take the battery to an experienced mechanic as soon as possible.

The good news is that most batteries have thermal and toxic gas sensors that prevent a complete meltdown of the battery and keep it from blowing up. We still urge you to pay attention to the warning signs and have the defective battery checked at the first sign of trouble.

How Do You Prevent Lawn Mower Battery Overcharging?

To prevent lawn mower battery overcharging, you can try investing in an automatic charger for your machine, building a circuit that prevents overcharging, keeping a close eye on the battery while it charges, or going for a voltage regulator for the mower’s engine.

Let us look at these four clever ways to keep your batteries from overcharging ever again.

Invest in Automatic Chargers

Using the right charger will never allow your battery to get overcharged. Take care of the original one that came with the mower and try to make it last as long as possible. Otherwise, buy automatic chargers that will stop feeding electricity into the battery once it is full and will let you know as well.

If your battery is 12 volts, then a 12 volts charger with a flow of 10 amperes per hour is a must. If not, look for a voltage-regulated one that allows you to set the voltage of your choice. Ditch and exchange those Rapid chargers for regular ones.

Build a Circuit That Prevents Overcharge

Building an overcharge protection circuit will give your battery an extra layer of safety if you are good with electric equipment. Even if you can’t build one yourself, we are sure your local hardware professional can put one in for you.

With this circuit in place, the connection between the charger and the battery automatically becomes null after a set time has passed, so that even if you have to use a non-automatic charger or forget to unplug it, your battery will stay safe.

Keep a Close Eye on the Battery While It Charges

This is easy, but only a few can commit to this method. All you have to do is be vigilant about when to disconnect the charger from the switch.

Most chargers take a set amount of time to charge the battery in one go. Notice how much time yours takes, then set a timer each time you charge your machine. This would ensure you remember to take the charger out when it’s done and no later.

Go for a Voltage Regulator

A voltage regulator also helps with overcharging as it disconnects the mower’s engine from its battery. The engine will only use power from the battery at a particular voltage.

It can strain the battery when used for a long period, though, and must be used with a trickle charger only.

How Do You Safely Charge a Mower Battery?

To safely charge a mower’s battery, make sure you are wearing protective clothing and follow important safety precautions. Use a 12-volt battery charger and connect it to the lawn mower’s battery. Keep the charger plugged in until it is fully charged, and unplug it immediately after.

Learn how to charge your lawn mower’s battery professionally to make it last as long as possible. This will also prevent overcharging, battery damage, and potential damages from occurring.

Follow Important Safety Precautions First

Wear thick rubber gloves when dealing with potentially dangerous electric equipment. Change your shirts and shorts for full-sleeved clothing that does not leave your skin bare. Wear safety goggles to keep sparks from getting into your eyes.

For those who wear metallic jewelry on their hands, take them off during charging. Ensure the engine is turned off first, then take the spark plug off. This is important for preventing the engine from turning on accidentally.

Go through the instructions manual of your mower to see if the manufacturers have given any special instructions for charging batteries.

Find Out Where the Lawn Mower Battery Is Located

If you know where the mower’s battery is located, refer to its instructions manual for guidance. In most riding lawnmowers, the battery is either under the seat or the hood. Lift the seat or the hood to gain access to it.

There are many different lawn mower designs, and your battery might be elsewhere. Even if your instructions manual has been misplaced, you can still go online and check the manufacturer’s website regarding the location of the battery.

It would help if you kept the battery in its place to charge it. This is much more convenient and safer than removing and attaching batteries each time for charging.

Use a 12-Volt Battery Charger

Lawn mower batteries display on a label the voltage at which they operate. Check it out to see the voltage of your battery. Most newer models operate on 12 volts, but there may be some older models with a six-volt battery for which you will need a six volts charger.

For most batteries, purchase a standard 12-volts charger, preferably from the same manufacturer. Make sure that the charger runs on at most 10 Amperes per hour. Chargers with amperes more than this are not suitable for lawnmowers.

Some chargers come with the option of adjustable amperes per hour. These might be more expensive than ordinary chargers but can be used on different batteries, which is a major plus point.

Connect the Charger and the Battery

Find out where the battery’s positive and negative terminals are located and clean them using a paper napkin. Before connecting the charger to the battery, disconnect the charger from the electricity supply first.

The color red, the letter P, or the plus sign mostly denote the battery’s positive terminal. First, the battery’s positive terminal needs to be connected to the positive clamp of the charger. Then connect the battery’s negative terminal to the charger’s negative clamp.

An N, a negative sign, or the color black denotes the negative terminal. Once these terminals are connected, move away from the mower and plug the charger back into the socket.

Keep the Battery Plugged in Until Charged

An adjustable charger helps you decide the right voltage, amperes, and charging time. Adjust the settings on it to match the voltage and the ampere of the mower battery. Even if the charger is of a fast type, still go for an average charging time and speed.

Before turning the voltage regulator charger’s switch on, ensure everything is set and settled. Allow the battery to charge while keeping it continually plugged. An automatic charger will turn off automatically when the battery becomes fully charged.

Unplug the Charger

If the charger isn’t automatic, then notice the time when you switch the charger switch on. After exactly one hour, your 12 volts battery would have charged fully. The charging indicator will also display a fully charged sign or turn completely green. Be sure to plug the charger off after one hour is over.

Remove the charger’s clamps from both terminals of the battery. In the case of a lead-acid battery, you must wait five to six minutes after turning the charger off before you can unplug the terminals. While unplugging, disconnect the negative terminal first and the positive terminal next.

Conclusion

Such a long and comprehensive guide calls for a brief recap as our conclusive words.

• It is easy to overcharge a lawn mower battery when the charger is not automatic, and you need to keep a vigilant eye over it.
• When a battery is constantly overcharged, it gets overheated and produces toxic fumes.
• Always invest in a good-quality automatic battery charger that is voltage regulated and runs on 12 amperes per hour.
• The least you can do to prevent your riding mower’s battery from overcharging is to keep an eye on it so that you can turn it off at exactly 100 percent.

Take lawn mower charging seriously for good battery life and an engine that runs smoothly. Always try to charge your batteries in one go and use the best quality charger, preferably from the company that manufactured your lawn mower.

​How to Tell Your Lawn Mower Starter Solenoid is Bad: SOLVED!

Home » Blog » Lawn Mowers » ​How to Tell Your Lawn Mower Starter Solenoid is Bad: SOLVED!

I jumped on my lawn mower to start it and all I heard was a clicking sound when I went to start my mower. Electrical problems can be pretty hard to diagnose and take a lot of time to narrow down the issue.

It’s a good idea to narrow down the problem and not throw expensive parts at the mower hoping it fixes the issue.

Here are some of my favorite items I use when testing my battery and diagnosing electrical items on my lawn mower: volt-ohms meter, battery charger, and continuity light.

Additional guides that may help:

• Lawn mower clicks and won’t turn over
• Why does my lawn mower battery keep dying
• Reasons a lawn mower won’t start
• Reasons a zero turn won’t start

This post may include affiliate links. Purchases made through these links may provide a commission for us, at no extra cost to you. As an Amazon Associate, we earn from qualifying purchases.

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 Lawn Mower Solenoid?

A lawn mower 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 can be found mounted on the starter. However, it does not have to be mounted on the starter to do its job.

Some lawn mower solenoids can be found mounted 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 Lawn Mower Solenoid?

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 right to the top of the starter and others attached to the frame.

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

You will find solenoids on every electric start engine. Not only will you find solenoids on electric start lawn mowers, but you will also find them in trucks, cars, and tractors.

What Causes a Lawn Mower 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 lawn mower 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.

It is good to know what to look for when you are diagnosing a solenoid.

Symptoms of a Bad Solenoid on a Riding Lawn Mower

A riding lawn mower 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 Lawn Mower 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.

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“.

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

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 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.

Test the Solenoid

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 Lawn Mower Solenoid?

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

Related Topics

Another reason why your mower may not start is due to water in the electrical system. Read our article “Why Your Mower Won’t Start After Leaving in the Rain”.

Starter Solenoid FAQ

Symptoms of a faulty solenoid are a clicking or humming sound when turning the ignition key, wiring getting hot and smoking, and the starter engaging and not disengaging after letting go of the ignition key.

When the starter solenoid fails, it will not provide the current required to engage the starter motor to turn over the engine.

A starter may click but not crank or turn over when the solenoid isn’t providing the power to turn over the starter. This may be due to a weak battery, loose or corroded wiring, or a faulty starter solenoid.

A lawn mower solenoid is an on/off switch of sorts. It is an electromagnet switch that is actuated to engage the starter motor by sending more current to turn over the engine.

The lawn mower solenoid is either attached to the top of the starter motor or to the frame of the mower. You can easily locate the solenoid by following the positive red cable from the battery to the solenoid.

Still Having Problems with Your Lawn Mower?

Lawn mower ownership doesn’t come without its frustrations. Own a mower long enough, you are bound to run into many lawn mower problems including starting, smoking, leaking, cutting, and overheating.

For mower troubleshooting, check out my guide Common Lawn Mower Problems: Solved.

Saturday 24th of June 2023

Motor stopped in the middle of mowing for no reason at all. Would not crank over then. I think now it could be my solenoid bad I will check it out. but whey would it just shut down?

The starter solenoid is used to engage the starter motor to start the mower. It will not cause your mower to quit running after it’s started, but it will keep a mower from starting. I would check the safety switches on your mower. A bad switch can cause the mower to stop running and also be a reason your mower won’t start.

Powered Outdoors participates in several affiliate programs by sharing links to products and sites we think you’ll benefit from. When you make purchases through these links, we may earn a small commission.

Lawn Mower Parts

Search and shop all the parts you need for your riding lawn equipment and Gator UTV including lawn mower blades, filters, belts, spark plugs, oil, and home maintenance kits.

Find Parts

Search part numbers and John Deere parts diagrams to identify exactly what you need to keep your equipment running smoothly.

Quick Reference Guides

As a John Deere owner, when it’s time to maintain, service or repair your equipment we have easy-to-use information sheets that keep your John Deere equipment running well.

Home Maintenance Kits

Feel confident in tuning up your lawn mower or garden equipment this season with our Home Maintenance Kits. Easily find the right product so you can DIY and save!

Looking for your Serial Number?

Finding your lawn mower’s model number and serial number is as easy as locating the identification tag on your machine. As seen in the example, the model number will be displayed below the MODEL heading (Example: Z235), and the serial number will be underlined on the top-right corner of the tag (Example: 130002).

If you’re looking for the engine number, that can be found directly on the engine itself.

Home and Garden, eat your heart out.

Get the latest on how to care for and enjoy your yard and garden. The articles and videos are informative and the ideas are amazing.

MowerPlus Mobile App

MowerPlus is the app you need to keep your John Deere riding lawn mower running well and your lawn looking great this season. The app tracks and records yard tasks and serves as a one-stop shop for seasonal care tips and maintenance activities. Know your mower and know how you mow with John Deere’s MowerPlus app.

The Right Part. The Right Price.

At John Deere, you get the value of choice for your maintenance and replacement parts for all makes and ages of machines – at any budget.

Genuine Parts

Genuine John Deere Belts Blades are your best choice for your newer machines.

Alternative Parts

Alternative Parts are an economical solution for your John Deere equipment.

The John Deere Easy Change™ 30-Second Oil Change System

Never drain engine oil again.

We’ve changed the oil change. Revolutionized it really. See how fast and easy changing your oil can now be on 100 Series Riding Lawn Tractors with the John Deere Easy Change™ 30-Second Oil Change System. Only from John Deere. Included on the E120, E130, E150, E160, E170, and E180 models.

Step One. Take it off.

Lift the hood. Make sure the engine is cool, then, twist to remove. It’s that simple.

Step Two. Twist and lock.

Grab the new Easy Change™ Canister, twist and lock into place. Make sure the arrow on your Filter System aligns with the arrow on your engine.

Step three. Done.

Close the hood and mow. John Deere recommends the Easy Change™ 30-second Oil Change System every 50 hours or at the end of your mowing season. Don’t drain engine oil ever again.

Draining engine oil is so 2017.

The engine modifications and new technologies are in. The re-envisioned oil filter with a media designed to resist breaking down in oil over time is here. The thousands of hours of testing are done. The end result is an all-in-one, oil and oil filter system like no other. The first of its kind. And thanks to the new John Deere Easy Change™ 30-Second Oil Change System (“System”), you’ll never have to drain the oil from 100 Series Riding Lawn Tractors again.

Here’s why: The new System captures contaminants and recharges your engine with nearly a quart (0.8qt) (0.76 l) of new oil. In fact, this System increases the amount of oil in the engine by nearly 40%. 2 Your engine likes that.

What do you mean, I will never have to drain oil from my engine again? How is that possible? The answer is simple. We have developed a better filtration system and filter design for our 100 Series Riding Lawn Tractors 1. This fully synthetic filter media has greater surface area which increases its capacity to hold harmful contaminants. What’s more, the filter media is designed to resist breaking down in oil over time. Which means you’ll get a cooler running engine. And a cooler running engine and better filtering helps increase engine oil life. John Deere’s recommended oil service for 100 Series Riding Lawn Tractors 1. is to change the System every 50 hours or once a season, whichever comes first. Remember, the System replaces a portion of your engine oil. And that’s plenty.

The System uses John Deere Turf-Gard™ Oil. Using John Deere Turf-Gard™ Oil ensures you are using the exact oil specified by John Deere engineers.

Testing. Testing. Testing. Thanks to thousands of hours of rigorous and extensive testing, you can feel confident your engine will run for years to come.

1 The John Deere Easy Change™ 30-Second Oil Change System is available on E120, E130, E150, E160, E170 and E180 Lawn Tractors today.

2 Compared to similar V-Twin engine models that do not have the John Deere Easy Change™ 30-Second Oil Change System. That includes equivalent Deere 2017 models and 2018 models without the System.

Frequently Asked Questions:

What is new with John Deere Riding Lawn Equipment?

We are excited about the exclusive John Deere Easy Change™ 30 second oil change system. Exclusive to John Deere and only available on certain models of the new 100 Series Lawn Tractors. These tractors are designed for ease of use for both operation and maintenance. The John Deere Easy Change™ System (“Easy Change”) allows the user to easily complete the recommended engine oil and filter maintenance in 30 seconds.

What is this new oil change system?

We changed the oil change. The all-in-one oil and oil filter system gives the owner the ability to change a portion of the oil and the filter in less than 30 seconds.

What happens to the rest of the oil in the engine when the Easy Change system is replaced?

The Easy Change system replaces.8 quart of oil. The remaining oil in the engine is refreshed by the charge of new oil included in the replacement Easy Change system. Combined with 40% more engine oil capacity, improved filtration and cooler running temperatures which help extend oil life, it is no longer necessary to remove and dispose of all the oil in your engine during service.

What makes the Easy Change system unique from other filters?

It is not just a filter. It is a newly developed technology system that allows a new “filter” to come already charged with oil and allows you to remove an existing filter and the contaminants inside without tools and without making a mess. Beyond the filter, technology within the canister and on your engine makes this possible.

Models with the Easy Change oil system use a fully synthetic filter that has more capacity to trap and hold contaminants. The larger surface area of the Easy Change canister acts like a radiator helping the oil to stay cool.

Does the Easy Change system somehow decrease the life of the engine?

The John Deere 100 Series lawn tractor models, with and without Easy Change, are specified for the same lifetime and are rigorously tested to the same standards to ensure the life of the tractor meets expectations.

Can I add the Easy change system to an existing tractor?

Because this system also requires unique features within the engine, the Easy Change system cannot be added to an engine that was not equipped with it at the factory.

Can I change all the oil if I choose to?

You could if you wanted to. There is an oil drain plug. It is not required for maintenance.

How often do I need to change the Easy Change canister?

Every 50 hours or once a year. The 100 Series Lawn Tractors with and without the Easy Change system have the same maintenance schedule.

What type of oil is recommended?

We recommend only John Deere Turf-Gard™ 10W30 Oil. The Easy Change canister comes pre-filled with John Deere Turf-Gard™ 10W30 oil.

How do I recycle the old oil?

Many local government recycling programs, authorized retailers, auto repair stations, and auto parts stores will puncture and recycle used oil filters and oil.

Do I ever need to add oil?

Yes. Consistent with our service recommendations for this product, you should check oil level daily and add oil if required.

Mower Only Starts When I Jump Solenoid? (Why What to Do)

There’s nothing more frustrating than having to switch your mower on, open the hood, and use a screwdriver to fire up the engine. And if anything, it’s a bit dangerous. If this is your current method, then you are jumping your solenoid. While this certainly works, it’s definitely not a convenient way of starting your lawn mower every time you want to use it. So, instead of putting up with this annoying process, let’s take a look at why your mower only starts when you jump the solenoid and see how to fix it.

Why Does My Mower Only Start If I Jump the Solenoid? (The Short Answer)

The starter solenoid is an electromagnet that is energized by a control cable connected to the ignition. The control cable circuit can become damaged and fail to give the solenoid the necessary power needed to activate and become energized. In addition, the internal components of the solenoid can wear down, resulting in a break in the starter electrical circuit. Jumping is a manual method to bypass the task of the solenoid.

Mower Not Starting Unless You Jump the Solenoid (4 Possible Reasons)

Within the starter circuit, there are several components that can stop your lawn mower from starting. So, let’s go over how you can diagnose which part is at fault.

Ignition

The ignition is responsible for providing the starter circuit with the temporary power needed to activate the starter solenoid. Therefore, if there is a fault with the ignition, the activating power will not reach the solenoid.

To test if the ignition is causing the problem, you need to test the output voltage of the ignition. So, take a multi-meter and connect the ground to either the lawn mower’s frame or to the battery’s negative side. Then, connect the positive side of the multi-meter to the starter terminal of the ignition switch.

Once you have everything connected, turn the key and test the voltage on the multimeter. If you’ve got a 12v mower, then you should see a 12v reading confirming the ignition is providing the required power. If the reading is under 12v, then you’ve found the root of the problem.

Control Cable

There is a control cable that connects the ignition to the solenoid. If this cable gets damaged, like there is a break, then it will lose continuity. If this happens, then power will not be able to reach the solenoid.

To check the cable, you can test the continuity or the voltage. Now, all multimeters have voltage testing, but not all of them can test continuity. Therefore, we’ll use voltage to check the control cable. To do this, connect the negative side of the multimeter to the negative battery terminal, then connect the positive side of the multimeter to the furthest cable end away from the ignition.

Now, turn the ignition to start and check the reading of the voltage. Again, you should see a reading of 12v for your 12v lawn mower.

Terminal

If you look at the terminals, you will see a number of connections on the various components of the starter circuit. If any of these are loose or corroded, then the electrical circuit will be broken.

To test the terminals of the starter circuit, you will need to use a multimeter. Connect the negative side of the multimeter to test the incoming power against the outgoing power. You should be getting the same voltage going out as the voltage that is coming in.

If you see that there is a drop of voltage or no voltage at any point, you will have diagnosed the potential cause of why the solenoid is not working.

Solenoid

Inside the solenoid is an electromagnet. When power is provided to the electromagnet, the plunger inside the solenoid moves and completes the circuit between the battery and the starter motor. Inevitably, these parts wear down over time and can no longer complete the circuit.

In addition, the mechanism of the plunger can wear down and jam up. This deterioration process can be slow, which is why you’ll find that the starter solenoids can sometimes work on and off.

So, if you have tested everything else in the starter circuit and the solenoid is receiving the power to energize, then you’ll know the solenoid is at fault.

How to Fix a Mower That Won’t Start Without You Jumping the Solenoid

If you find that you are not getting the reading you were expecting during your testing, then you’re one step closer to resolving your starter problem. So, here are my fixes to overcome your mower only starting when you jump the solenoid.

Replacing the Ignition

Modern riding mowers, like Craftsman, have quick disconnect ignitions that are common on many riding lawn mowers. It will take you no time at all to change these types of ignitions, and you won’t need any tools either.

So, start by removing the main battery fuse and then remove the ignition key. Next, lift up the lawn mower’s hood and find the ignition behind the mower’s dash. For the quick release, you will need to squeeze the tabs on the back of the ignition. It’s a bit fiddly, but if you squeeze the tabs and push the ignition, you should be able to push the ignition through the dash.

Once you have the ignition free of the dash, you’ll see that it is connected to the wiring loom with a large connector. So, pull off the connector and attach it to the new ignition switch. Next, press the new ignition through the dash so that it clips into place. Finally, close the hood and refit the fuse. This is all you need to do to replace the ignition.

Tools Parts Required

Replacing the Control Cable

To replace the faulty control cable, you have two options. You can either replace the individual cable or completely replace the ignition wiring harness. Now, as ignition harnesses are not all that expensive, I recommend you replace the whole thing. That is, unless you happen to enjoy electrical work.

So, to swap out an ignition harness, all you need to do is disconnect the individual connections and connect the new harness. I suggest that if this is the route you are going to take, then swap out one connection at a time. Doing it this way will prevent any confusion and wrong connections.

Tools Parts Required

Cleaning Up the Terminals

To clean corrosion on the terminals, you need to get hold of a small wire brush and some electrical contact cleaner. Start by disconnecting the battery, then grab the cleaner. Give the terminals and connections a good spray with cleaner and allow a few minutes for it to do its work.

Once the cleaner has soaked in, take the wire brush and brush off the affected areas. You will probably need to apply a few sprays of the cleaner for it to do a good job and remove all of the corrosion.

Once you have cleaned the terminal and connector, double-check how they fit. During your diagnosis, you may have found some loose connections. You might find that pinching the connector with a pair of pliers helps to get a tighter fit.

Also, for connections that require a nut and washer, check to see that the washer hasn’t totally flattened out. A lot of electrical connections on lawn mowers use tooth and split washers so that they stay in place with all the mower’s vibrations. So, if they don’t look any good, swap them out.

As a safety precaution, be aware that corrosion on batteries can burn your skin, so it would be a good idea to wear a pair of protective gloves.

Tools Parts Required

• Electrical Contact Cleaner
• Small Wire Brush
• Pliers
• Replacement Washers
• Small Socket Wrench Set
• Screwdriver
• Protective Gloves

Replacing the Solenoid

Ride-on lawn mowers, such as Gravely and John Deere, use an inline starter solenoid that bolts to the frame of the mower. This is very common for ride-on, tractors, and zero-turn lawn mowers. So, if you have this type of starter solenoid, this is what you are going to have to do to swap it out.

First, disconnect the cables from the battery and tuck them out of the way. Then, take a socket wrench and remove the nuts holding the cables to the solenoid. Next, remove the mounting bolts that hold the solenoid to the frame of the lawn mower. Once these bolts have been removed, the old solenoid should come free from the mower.

Now, grab your new solenoid and bolt it to the mower using the same bolts that you previously removed. Then, attach the electrical cables to the solenoid and tighten the nuts using your socket wrench. Finally, reattach the battery cables and give the lawn mower a try.

Tools Parts Required

If you successfully diagnosed why your mower only starts when you jump the solenoid, these fixes should stop you from having to use a screwdriver instead of the ignition key.

About Tom Greene

I’ve always had a keen interest in lawn care as long as I can remember. Friends used to call me the lawn mower guru (hence the site name), but I’m anything but. I just enjoy cutting my lawn and spending time outdoors. I also love the well-deserved doughnuts and coffee afterward!

Leave a Reply Cancel reply

Copyright © 2010. 2023 LawnMowerGuru.com, All Rights Reserved.

Affiliate disclosure: As an Amazon Associate, we may earn commissions from qualifying purchases from Amazon.com. You can learn more about this here.