How To Test A Lawn Mower Ignition Switch

How To Test A Lawn Mower Ignition Switch [Step-By-Step]

5 minutes

The ignition switch of a lawn mower is the most crucial component which helps to start the engine. And if your mower fails to turn on, then there is a chance of having an issue in the ignition switch. 

To figure out the fault in the switch, you need to understand how the switch works and it’s defective symptoms. And for that you must know how to test a lawn mower ignition switch.

That’s why today I’m here with you. In this article, I will guide you step by step of how you can test a faulty ignition switch. Also, I’ll be providing some symptoms of having a bad ignition switch as well. 

Symptoms Of A Defective Ignition Switch 

If you are facing an issue with your engine, there is a chance of having a faulty ignition switch in your lawn mower. So, if your mower’s ignition switch has any fault, you will notice the following signs. 

Key Won’t Turn On

If the key gets stuck and doesn’t turn on to the start state of the engine, then there is a fault in the ignition switch. 

Overheating Issue 

It’s another prominent issue where one end of the wire might become excessively overheated. 

Lawn Mower Stalls 

While starting or moving the lawn mower, it might stall after some time. 

Engine Won’t Start 

Another significant issue is that the engine attempts to start but fails every time. This might be due to faulty or broken ignition switches. 

Steps Of Testing A Ignition Switch 

Different types of procedure can be followed to test the lawn mower ignition switch with the help of digital and analog multimeter. You can follow any of the methods to test your mower’s ignition switch. 

1st Method Of Testing The Ignition Switch

  1. Get the “fuse panel”, lying under the “steering”, and open it. Now, get the starter signal fuse from the panel and check carefully whether the metal strip is in good condition. 
  2. Change the metal strip with a good one if it’s found to be damaged or defective. Make sure the new one comes with the same amperage as the damaged one. 
  3. Connect the digital multimeter to the positive and negative terminal on the battery. Recheck whether the red lead of the voltmeter is connected to the positive side of the battery. 
  4. The voltmeter marking should be at least 12.6 volt for moving the engine with its full speed. But if it becomes less than 12 volt, then probably the battery is dead. 
  5. To check the ignition switch, start your engine by putting the key to the switch. If the engine fails to start and at the same time, you don’t hear any clicking sound, then the ignition switch isn’t working. 

On the other hand, if you are hearing the clicking switch but the engine fails to start, then the issue is in the battery.

Lastly, if the engine starts successfully, both battery and ignition switch are okay. 

2nd Method Of Testing The Ignition Switch

1. Replace the spark plug with an old plug to the end of the boot and power the engine placing the key to the ignition switch.

Now check the ignition switch by checking whether there is a continuous spark to the old plug. If there is no spark, surely the switch of the lawn mower is faulty. 

2. Connect the voltmeter to the coil’s positive and battery’s negative terminal of the lawn mower. If the voltage of the battery is on the positive side, your ignition switch is okay. Otherwise for lower reading, there can be an issue with the switch. 

3rd Method Of Testing The Ignition Switch

  1. For beginners, check the multimeter carefully and turn on the key. Place the multimeter’s positive end to the power supply and the negative end to the distributor’s base. 
  2. Place the key to the running position in the ignition switch and inspect the voltage of the battery using the multimeter. 
  3. If the reading of the voltage is lower than 90% of the main battery’s voltage, then there is a huge chance of having an issue in the ignition switch or wire. 
Replacing The Ignition Switch

Replacing The Ignition Switch 

Once you have done testing the ignition switch, it’s time for taking the necessary steps, depending on the problem. Identify the underlying problem and replace the ignition switch if needed. 

Replacing an ignition switch is complex work. However, if you have a good technical knowledge, you can simply change the ignition switch without any trouble. Otherwise, you can visit any nearby engine repair shop to take help from professionals. 


In some cases, testing the ignition switch’s issue and resolving it becomes very frustrating and tiresome. But hopefully, following the above method will make your work easier. 

Nevertheless, regular cleaning and operating the lawn mower will lessen the tendency of having technical issues in the inner components. 

Todd L Miles
Lawn Mowers Enthusiast
I started "Landscape and Lawns Care" to provide clients with lawn care with better service, better products and, most importantly, better ethics. My promise to every customer is to give the greenest grass possible while controlling weeds, insects, and diseases! The most important thing is that I strive to always do the right thing for you, your lawn and your wallet!