How to Make a Kill Switch for a Lawn Mower

A kill switch is a safety device that will turn off the lawnmower if it becomes caught on something. This prevents the machine from becoming dangerously out of control and harming anyone in its path. Making your kill switch can be a quick, easy way to ensure your family’s yard remains safe. 

In this article, we’ll show you how to easily create one for any push or riding lawn mower with just a few simple supplies. One of the scariest moments for a homeowner is mowing their lawn, and something goes wrong. The worst scenario can be avoided with a kill switch. A kill switch will stop the engine if it becomes dangerous, like catching on fire or running off course. This article will walk through how to make a kill switch for a lawn mower. 

How to Make a Kill Switch for a Lawn Mower

Why Should You Make a Kill Switch for a Lawn Mower?

1. To stop your gasoline lawnmower, the best way is to turn off the fuel and pull out the spark plug. If, for example, you need to inspect under your mower’s deck without turning off the gas first, this can be helpful. If you remove the spark plug first, there will be no gas in the line, and it will be safe to start removing the deck.

2. If you are riding your lawnmower through an area where you do not want to cut any more grass or where there are plants that your lawnmower may damage, you cannot quickly turn off the blades without removing the spark plug. The spark plug prevents the engine from running and will also prevent the blades from turning.

3. If you are cutting tall grass or weeds, the blades will stop moving while the engine is still running unless you release the kill switch lever.

4. You can damage your lawn mower by accidentally leaving it in gear while it is idling. This often happens when people sharpen their blades and need to move them around with the motor running. This can be dangerous as you could injure yourself or others, damage the mower blade, and even start a fire if you work with gasoline. How do you start a lawn mower with a blade on it?

5. You will not have to worry about forgetting that your lawnmower is still in gear, which is very dangerous because someone could easily get caught by a moving lawnmower.

6. You can easily transport your lawnmower in the back of your truck because you can disconnect it without having to stop the engine first.

10 Ways on How to Make a Kill Switch for a Lawn Mower:

A kill switch for your lawnmower is an excellent addition to the safety of your riding lawnmower. Lawn equipment can be dangerous if it is not used correctly, but with a few tools, you can make yourself a very safe kill switch that will ensure no one gets injured while using your lawnmower. Here are ten ways how to make a kill switch for a lawn mower:

1. Pull Starter:

A pull start kill switch is a cord that attaches to the starter cord. When you pull the cord, it turns on the lawnmower, and when you let go of it, it stops. This type of kill switch can be dangerous if not done correctly because someone could still walk into the mower’s path and get hurt.

2. Clutch Cable:

A clutch cable kill switch is a metal wire that attaches to the clutch lever arm on your lawnmower’s engine and goes under the mower’s handlebar. When you squeeze the clutch, it releases an electrical connection from one end to another, stopping the electrical current to the spark plug and the motor. This type of kill switch will prevent injuries, but it can also be dangerous for small children or pets that could get caught in the blades.

3. Bar with Wire:

A bar with a wire kill switch is a metal rod that goes through your lawnmower’s handlebars, and when you lift the bar, it breaks the electrical connection to the spark plug, which stops your lawnmower. This type of kill switch is simple and effective, but it can be dangerous if you or anyone else lifts the bar while using the mower.

4. Seat Switch:

A seat switch kill switch is activated when you sit down on your lawnmower. You can attach a wire that runs from the bottom of the lawnmower to the top of it, going through your handlebars and connecting to a switch inside of your seat. This will keep an individual safe but may not be ideal for everyone riding a lawnmower because you can’t easily adjust the height of your heart.

Ways on How to Make a Kill Switch

5. Mow-Stop Switch:

A mow-stop switch is connected to the blades of your lawnmower, and when you hit something like a bit of stick or rock, it stops the edges of your lawnmower, which contains the rotation of the engine. This kill switch is relatively safe because if someone runs into it, it will stop the blades, and nothing harmful will happen.

6. Key Switch:

A key switch kill switch is like a standard light switch you have in your house, but with an electrical current to it. This type of switch needs to be wired with the lawnmower’s ignition, so when you turn on the mower, it turns on all the electrical parts, including the engine. When you turn off the ignition, it stops. This type of kill switch is safe because no one can accidentally hit or start the lawnmower when they are in the path of the mower’s blades.

7. Speed Controller Switch:

A speed controller switch electronically controls how fast or slow your lawnmower’s engine will run. This type of kill switch is usually wired into the speed controller on your lawnmower, so when you turn up the speed, it increases the electrical current to increase how fast your mower can go. If someone ran into this switch, it would simply stop the mower from going as quickly and nothing else would happen.

8. Servo Motor:

A servo motor kill switch is wired into your lawnmower’s engine, so when you turn all the electrical parts on, it activates the machine by increasing the rotation of the blades. If someone were to hit this type of switch, nothing would happen except making sure your lawnmower stops.

9. PTO Switch:

A PTO switch, or power take-off switch, kills the engine by disconnecting its brake lines from the clutch. This type of kill switch is wired into your lawnmower’s brake line, and when you turn it on, it breaks the electrical connection between the two creating a safety switch. If someone were to hit this kill switch, it would stop the blades from rotating, and nothing harmful would happen.

10. Remote Control:

A remote-control kill switch is a wireless device that can be put into a bag or a pocket when you’re mowing your lawn, but if something happens and you need to stop your mower immediately, you can hit the kill switch, which controls the blades of your lawnmower. This type of switch is suitable for individuals mowing their lawns to prevent injuries, but it can be dangerous because anyone could set off the remote control to stop your mower.

Precautions and Safety Measures:

1. You will be working with a gas-powered lawnmower, so make sure the engine is turned off before attempting to work on it.

2. Some parts of the lawnmower are sharp and can cause injury if touched or caught on clothing; please be careful when connecting any parts of the machine.

3. Make sure the lawnmower is placed in a well-ventilated area when underuse.

4. A fire extinguisher should be kept nearby in case of an emergency.

5. You should wear gloves when working with lawnmowers due to their sharp edges.

6. Follow all safety precautions that are outlined in the user manual. Failure to do so can result in injury or death.

7. If you are not confident, please seek assistance from someone more experienced or read the entire guideline on how to make a kill switch for a lawn mower before proceeding.

How to Test the Kill Switch?

First of all, test the system between an old battery and a new one you want to use on your lawnmower. Then, connect the two batteries at their positive (+) ends utilizing a piece of wire or cloth dipped in saltwater or battery acid. The old battery should act as the ground (-), while the new battery will serve as the power.

Testing the Kill Switch

If the old battery starts charging the new one, your kill switch is working correctly. These batteries should drain at different rates (this will be due to their overall health), which you can determine by monitoring their voltage levels. You’ll want to make sure that each of them gets drained down to about 1V before disconnecting them.

If the old battery doesn’t start charging the new one, then check to see if you have a broken wire somewhere between your old battery and your switch. If that is not the case, then it could be possible that you have the polarity of the cables backward. You can use a Digital Multi-Meter (DMM) to check for this.

Frequently Asked Questions

Why won’t my lawn mower shut off?

If your lawnmower is having trouble shutting off, it could be because the engine is overworked. If the engine is working too hard, it may not have enough time to cool down between uses. This can cause the engine to overheat and shut off.

The blade on the lawnmower may be stuck in the grass. If this happens, the blade will keep spinning and damage the engine. You will need to remove the blade and clean it to fix it.

If neither of these solutions works, you may need to replace the engine.

Why does my lawn mower keep running after turned off?

The most common reason why lawnmowers keep running after being turned off is because of a clogged gas or oil line. If the line is clogged, the engine will keep running until the line is cleared.

To clear the line, you will need to use a plunger to suction onto the end of the line and push and pull until the obstruction is removed. Make sure to wear gloves and avoid getting any grease or oil on the lines.

Can a bad spark plug cause a mower to stall?

A bad spark plug can cause a mower to stall, but it is not the only thing that can cause this. A misfire in the engine may also be responsible for the mower stalling.

Will a dirty air filter cause a lawn mower to stall?

A lawnmower has filters that help it trap small particles and dust. If the filter gets clogged with dirt or other things, the lawnmower might not work as well.

Why is my mower dying?

A few things can cause your mower to die, and fuel starvation is the most common.

When your mower’s engine runs out of fuel, it will not be able to start. This can happen if the gas cap is not tight or if too much grass is caught in the blades.

To fix this problem, you must remove the grass from the blades and refill the fuel tank with fresh gasoline. Make sure you do this before mowing again so the engine does not run out of fuel again.


To make a kill switch for your lawnmower, you will need to find an old-fashioned phone cord. First, cut the end of the wire off with wire cutters and strip about half-inch of insulation from each side of it. You can then attach this wire to both ends of a push button mounted in an insulated box.

When you want to stop the blade on your mower, press down on the top half of the pushbutton until it clicks into place, which completes or interrupts power flow through one circuit in your home’s electrical panel system. We hope this blog post on how to make a kill switch for a lawn mower has been helpful. If you still have any questions feel free to let us know in the comment section below!

Check our article How to Build a Mini Bike With Lawn Mower Engine

Jennifer Branett
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