3 Most Common Lawn Mower Ignition Switch Problems

Let’s thank the ignition switches that manage the electrical system of your lawnmower and let you ride safely. But the problem arises when you deal with Lawn Mower ignition switch problems.

However, don’t worry about it, there are bigger things to be mad about. Leave this one on us. We’ve compiled here everything from a basic understanding of the ignition switch to their problems and fixes.

So, let’s get started without wasting a second!

How Does a Lawn Mower Ignition Switch work?

To deal with the annoying problems of a lawn mower ignition switch, you must know how the ignition switch works in the first place.

Things may seem a bit surprising to you that the ignition switch stays in the off position while the engine is running. Yes, it sounds weird.

And, when the engine is stopped, the switch will turn on and create a path to the ground. When you ride on the mower, previously, the electricity was flowing to the spark plug. But then it starts to flow to the engine ground and finally, the engine stops running.

There is a white wire and a coil inside the solenoid of your mower. And, the ignition system transmits the power through the wire and gives the coil energy when you turn the key to start your mower.

Also, there are red and black wires in the machine. Initially, the coil helps to close an internal contact and it allows the power to flow from the red wire to the black one. And, the whole process provides the power to the starter motor and it spins the engine.

As you might guess, the ignition switch is what allows you to start, run, and even turn off your mower. The sole purpose of the witch is to let you safely engage the whole ignition system as well as activate the electric structure.

When you do not use the mower, the battery of your mower should be safe from draining. In this case, the ignition switch manages the electrical system to make sure of it. 

You will find five letters on the back of your ignition switch and you may become confused thinking what they do mean.

The table below will help you to understand.

SStarter Solenoid

How To Identify Lawn Mower Ignition Switch Problems

Before going to solve the problem, a basic question ‘how to identify lawn mower ignition switch problems?’ may spring straight to your mind.

Turn the key of your mower to the start position. Then use a multimeter to measure the resistance between S and B terminals. Make sure that the first meter-probe gets in touch with the B prong on the ignition switch’s back whereas the other probe is with the S prong. Check the resistance after starting the engine.

The result should show a resistance near zero ohms. But if there’s an infinite level of resistance, you need to replace the ignition switch.

What the reason for this is, your ignition switch is supposed to close the contact B to S for sending voltage to the solenoid but it’s failed to do the job.

Moreover, the connectors are supposed to make a beeping noise with the multimeter. As long as you hear the beeping noise, it means your Lawn Mower ignition system is working well.

Besides, you’ll want to follow the lights for checking the connectivity and continuity of the Lawn Mower ignition switch.

These are the handy and quick tests you can do to identify if the ignition switch is faulty. If anything suspicious appears, it’s better to give them a professional check. Sometimes, a quick fix/replacement can save your entire tool from getting damaged.

3 Most Common Lawn Mower Ignition Switch Problems

The ignition switch of a Lawn Mower can get damaged by breaking, corroding, or loosening. These are the most common defects that create significant hassles with your Lawn Mower.

However, here are the consequences you can face for a problematic ignition switch.

  • Lawn Mower not getting started
  • The mower doesn’t shut off
  • Can turn the engine off

Reasons Why Lawn Mower Not Getting Started

Although there are some other reasons as well, a problematic ignition coil is one of the biggest reasons why your mower doesn’t get started.

Because, if there’s an issue with the ignition switch, the starter of your lawnmower will not get current. You may guess that when your engine won’t get the expected power supply, the mower won’t start.

Therefore, when your lawnmower does not turn on or off even if you turn on or off the key relatively, you have to replace the ignition switch. There’s no other way to deal with a faulty power supply, sorry.

However, as we were saying about the other reasons, have your eyes on the points that describe why else you can face the same problem.

  • Dirty air filter
  • The disconnected or loose spark plug in your lawnmower
  • A faulty fuel filter

Reasons Why the Mower Doesn’t Shut Off

Have you noticed that your mower doesn’t shut off at all? Does it only shut off when you disconnect the spark plug?

If this is the case, chances are the ignition switch has gone bad or maybe the ground wire got disconnected.

Can’t Turn the Lawn Mower Engine Off- Why?

A faulty ignition switch can cause this problem. As you know, the ignition switch controls your mower to start, run, and turn off, a dead ignition switch will fail to get the job done.

You can be sure of the problem with the test method we mentioned. Because the other reason to face the same problem is the control cable of your mower is potentially damaged.

You may ask now, what happens when your ignition switch goes bad?

In case the ignition switch fails while the engine continues to operate, chances are it will disconnect the power to both the ignition and fuel systems. It can lead the engine to get blocked. According to the very specific issue, the consequences will be something like your mower won’t restart for a while.

So, you need to know how you can fix the problems to avoid this inconvenience.

How to Deal With a Damaged Lawn Mower Ignition Switch

When it’s about a damaged ignition switch, chances are there are problems with loose wiring & connections, spinning motor, or corrosion.

So, when things are that bad, you need to replace your ignition switch. You may think it’s the end of the world but hey, replacing a bad ignition switch is the easiest and the best way to fix the problems.

Let’s see how we can do that.

Step 1: Detach the Battery

Wear gloves before you walk through this step. Turn off the ignition switch and take the key apart from the ignition.

Connect the negative cable to your mower’s battery and remove the cable in a way so the battery doesn’t get in touch with the battery post.

Step 2: Take the Ignition Switch Apart

Manage to access the back of the mower’s ignition switch.

Untie the locking tabs then. Done? Now, push out the switch through the front part of the dash.

You’ll find a wire harness attached to the ignition switch’s back part, disconnect it. You may find it a bit difficult to unplug, but simply wiggling the plug will help you to pull on it.

Step 3: Install a New Ignition Switch

Now, it’s time to connect that wire harness to the ignition switch’s pack part. After that, attach the new ignition switch to the dash. Finally, attach the locking tabs and lower the hood of your mower.

Step 4: Connect the Battery

You started the process by disconnecting the battery. And, now, you have to reconnect it. Remember, the negative cable is supposed to be connected to the negative battery terminal. Then, lower the seat and you’re all set. 

How to Avoid Lawn Mower Ignition Switch Problems?

The best thing you can try here is, avoiding such ignition switch problems. You obviously won’t be wanting to damage your entire tool because of some unconsciousness. Here I’ll mention some tips that you can follow for avoiding any ignition switch failure.

  • When you’re dealing with electrical tools, try to go for supreme quality. For a better and reliable ignition switch connection, make sure you’re using good quality jumpers, bolts, switches, wirings, etc.
  • Don’t overlook the minor engine issues with the tool. Even a tiny broken spring on the switch part can damage the entire ignition switch system. You might not have to spend that much money on the machine’s fault at the primary level. In the long run, these tiny mistakes can cause you to pay more bucks.
  • Test your Lawn Mower ignition switch regularly. For that, you can use a digital multimeter/ Dvom machine. If anything suspicious appears, it’s better to replace/ fix the damaged part as quickly as possible.

Frequently Asked Questions

What causes ignition switch failure?

Many things can cause ignition switch failure. The most common reasons are extreme temperature issues, poor ignition switch installation, forceful prevention of starting the machine, broken spring, and etc.

How much does it cost to replace the ignition switch?

Fixing your ignition switch system is a pretty expensive task to consider. Without the labor cost, you might have to spend around $125 to $275. If you add the labor cost, then it will altogether stand around $220 to $485.

Can you replace the ignition switch by yourself?

It’s true that replacing the ignition key requires good technical knowledge. But you can do it yourself by following our steps properly. Otherwise, If you think that it doesn’t seem like it’s your job, you can get help from professionals.


Yes, we know how irritating it is to face lawn mower ignition switch problems. But hey, we made your path easier with this well-crafted article, right?

Nevertheless, you always should take good care of your lawnmower to have a long journey with it. If you clean, maintain, and operate the machine properly, you can avoid any further hassle for sure.

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