How to replace starter solenoid on a lawnmower, step by step

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With your schedule cleared up, you plan to cut the grass with your trusty lawnmower. But as soon as you turn the ignition key, the lawnmower does not start. It means that either the battery or the lawnmower’s solenoid is the problem. This is the very first time you’ve come across a situation like this. Checking the battery is easy. Use a multimeter and check the voltage, if you measure around 12 Volt the battery is fine. That leaves the solenoid, but no need to worry. This blog helps to fix the problem.

How to replace starter solenoid on a lawnmower, step by step:

  • Step 1: Detach the solenoid from the mower’s body
  • Step 2: Test whether the solenoid is functional using a multimeter
  • Step 3: Purchase a new solenoid
  • Step 4: Install the new solenoid
  • Step 4: Test the lawnmower with the new solenoid

The lawnmower’s starter solenoid is typically located below the battery on the vehicle’s lower left side. It’s connected via screws to the lawnmower’s metal body. As its service life can end, the solenoid may also deteriorate, or its terminals can become weak due to corrosion. A 3-post solenoid or 4-post solenoid are the two types of a solenoid. For both, however, the procedure for replacing the solenoid is the same.

The section below includes in-depth descriptions of the above steps, such as what kind of equipment to use to replace the starter solenoid, making the solenoid connections, etc. Stay tuned to this post, as we are here to solve your problem without any further ado.

Replacing the lawnmower starter solenoid, a step-by-step approach:

The following method explains all the necessary steps to inspect the solenoid and, if worn out, replace it with a new one.

● Step 1. Removing the solenoid from the lawnmower:

Over time, the lawnmower solenoid may become faulty. Its terminals may become rusty because of the air’s humidity, or the metal plate within the solenoid may have stopped working. It should be removed from the lawnmower first to verify the root cause of the solenoid’s malfunctioning.

– Step 1.1. Turn the ignition off:

The solenoid is usually positioned below the battery, on the bottom left of the mower. Turn off the ignition switch and remove the key. This is done because you have to do some steps with the battery terminals, so it mustn’t be charged during that!

– Step 1.2. Remove the battery terminals:

Lift the lawnmower seat and remove the negative terminal of the battery. Likewise, remove the positive terminal from the battery. You have to remove the battery from the lawnmower, so battery terminals must be removed first.

– Step 1.3. Release the seat switch wire clip:

Detach the seat switch wire clip from the seat and take the battery out of the battery case. Then remove the retaining tabs and raise the battery box from the body of the mower.

– Step 1.4. Remove the wires from the starter solenoid:

A solenoid can be seen now, connected to the lawn mower’s metal body. Disconnect the wires attached to the terminals of the solenoid. Also, pull out the wires from the coil spades.

– Step 1.5. Remove the starter solenoid from the lawnmower:

 Next, remove the starter solenoid bolt from the mower’s frame by loosening the screws that attach the solenoid to the lawnmower’s metal body. Rotate the starter solenoid forward and take it out of the lawnmower.

– Step 1.6. Take a good photo of the connections!

It’s also an excellent choice to take a good snapshot from your phone before disengaging the solenoid’s connections so that it can help you reconnect the solenoid back into the lawnmower.

Since the solenoid has been removed, now it’s time to test it.

● Step 2. Test the solenoid using a multimeter:

 With the help of a 12V battery source and a multimeter, the testing procedure is carried out. The 3-post and 4-post solenoid testing strategies are the same, so no need to think about that!

– Step 2.1: The “click sound” test:

To perform this test, you need to connect the available battery’s negative terminal to the solenoid’s negative terminal first. If the solenoid is a 3-post solenoid, there is no separate connection to link the battery’s negative terminal. The battery’s negative is attached to the metallic screw plate of the 3-post solenoid in this case. However, in a 4-post solenoid, there is a separate connection available on the solenoid where the negative terminal of the battery is connected.

Now, after the negative terminal has been attached, as soon as the positive terminal of the battery is connected to the positive connection of the solenoid, the person conducting the test hears a “click sound” If no sound is present, this means that the solenoid is defective and needs a replacement.

– Step 2.2: The connectivity test:

In case the solenoid passed the test mentioned above, the next one on the list is the connectivity test using a multimeter. To perform this test, you shall make the positive and negative connections in the same manner as listed in the” click sound test.” The multimeter must now be switched to the beep testing mode. The multimeter’s positive and negative terminals need to be connected to the two main terminals located on the solenoid’s upper part. If the multimeter gives a beep sound, it means that the solenoid is perfectly functional and doesn’t need to be changed.

But if no beep sound is heard, it means that the solenoid is faulty and needs to be replaced.

● Step 3. Buying a new identical solenoid:

Now, as you have seen that the solenoid has failed the test, you know one thing that the only option available is to buy a new one and dispose of the old one. For doing that, you should ensure that the one you are purchasing is identical to the one being replaced. The crucial thing to be remembered is whether the faulty solenoid was 3-post or 4-post. So you should purchase the new one accordingly. It is better to consult the user’s manual of your lawnmower while doing this. While purchasing, always ask the seller to provide you the solenoid according to your particular model.

● Step 4. Install the new solenoid:

Maybe you are exhausted after going through such a long testing and shopping phase. Just hang on; you are almost at the point where your lawnmower gets up and running again. Installing the new solenoid into the lawnmower is just another last step.

– Step 4.1. Rechecking the ignition switch:

The first thing to be done is ensuring that the ignition switch is off and the key is removed.

– Step 4.2. Reattach the solenoid to the lawnmower’s body:

Switch the mounting clip from the old solenoid to the new one. Place the new starter solenoid on the lawnmower’s frame and install the mounting bolt, attaching the lawnmower’s metal body to the solenoid.

– Step 4.3. Reconnect the removed wires to the solenoid:

 Attach the wires to the coil spades of the solenoid. Next, on the terminal posts, install the cables, attaching them to the mounting nuts. The new solenoid has now been successfully mounted.

– Step 4.4. Install the battery back into the battery box:

In the gap, position the battery box and engage the retaining tabs. The seat transfer clip is now to be reconnected to the seat bracket. Lower the battery and align the battery cables in the battery case.

– Step 4.5.  Reconnect the battery terminals:

Reconnect the battery’s negative cable to the negative terminal and its positive line to its positive terminal. Put the insulating cover in place again. Lower the seat, and the lawnmower is now ready for testing!

● Step 5. Test the lawnmower:

After all the hustle of the day, why not test the lawnmower and take it to your garden for a spin? Turn the ignition switch by putting the key back in. Just guess what? The lawnmower has started and is humming as if it were a new one! Have a good day and make your garden even more beautiful than before!

For a hands-on demonstration of how to replace a starter solenoid, you should watch this video:

Related Questions:

1. My lawnmower wasn’t used even once in the winter, and now it won’t start. What may be the problem?

Before keeping your mower away for a long time, you must ‘winterize’ it. The main reason for start-up failure is the thickening and clogging of the lawnmower’s stored fuel. It would help if you poured in some fuel stabilizer into the stored fuel before putting the mower away for a long time to prevent the fuel from clogging.

2. The solenoid is requiring a replacement every month. What shall I do?

For some years, typically, a solenoid can do its job correctly until a replacement is necessary. The solenoid needs a replacement because, due to some debris or dust, the ground connection given to it might not be good enough. Ensure that there is a substantial ground for the metal on which the solenoid is installed. To get a better connection, remove the solenoid and use sandpaper to clean up the metal area on which it is fixed.

Final Remarks:

If you love your garden and your mood on a bad day is ultimately improved by gardening, then the lawnmower must be maintained and well cared for. It’s not a pleasant feeling if you turn the key on your lawnmower, but it won’t start. But after reading this post, the lawnmower’s solenoid can now be easily removed, checked, replaced, and reinstalled in your home. Our top priority is your well-being, so don’t forget to take some precautions when carrying out the testing process. Before starting the operation, you must always wear work gloves to shield you from accidental cuts. The wrench collection and other equipment need to be used with great caution and kept out of children’s reach. It would be best to detach the spark plug wire from the spark plug while lubricating a lawnmower to avoid the risk of an accidental start. Also, don’t forget to maintain other lawnmower parts, such as filters, cutting blades, oil, etc.