It’s time to cut the grass again. However, this time your mower won’t even turn over. Use this guide to troubleshoot your starting problem so you can get back to mowing before the lawn becomes an overgrown mess.
A riding mower won’t turn over when the battery is weak; the cables and wiring are loose or corroded; the fuse is blown; the safety switch is faulty; the ignition switch is bad; the starter solenoid is bad; the starter is faulty, or you have developed engine problems.
Take caution when working with the electrical system to avoid electrocution. Follow all safety precautions outlined in your mower operator’s manual.
Troubleshooting Steps: Engine Won’t Turn Over or Crank
- Check for a dead battery
- Look for loose wires and connections or corrosion on the wiring and terminals or bad ground
- Look for a blown fuse
- Check for a bad safety switch
- Check for an ignition switch failure
- Check the starter solenoid
- Have your starter motor tested and replaced if needed
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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.
This is Why Your Riding Mower Won’t Turn Over or Crank
1. Dead or Bad Battery
Your lawn mower relies on power from the battery to assist with starting. When the battery has a weak charge or is dead, it won’t turn over the engine.
The first thing you should do when your mower won’t start is to check the battery’s charge using a multimeter. A fully charged 12-volt battery should give you a reading of about 12.7 volts.
If you are getting a lower reading, charge the battery. You can find steps to test a battery in 5 Things That Are Draining the Life of Your Lawn Mower Battery. Here, you will also find information on what can cause your battery to lose charge.
Charging a Battery: Use a battery charger to charge your battery. Before you continue, wear protective gear to protect your skin from electrical shock and protect your eyes. Follow these steps to charge your riding mower battery with a charger:
- Access the battery and terminals. You may need to use a screwdriver to uncover the battery. You will find the battery under the hood or under the seat. Do not remove the battery from the casing.
- Connect the battery charger cables beginning with the positive cable first. This is the red cable or the one with the plus sign. Place the cable on the positive battery terminal.
- Attach the negative cable to the negative battery terminal. This is the black cable or the one with the negative sign.
- Do not touch anything that doesn’t have a rubber coating to prevent electrocution.
- Set the charger’s voltage and amperage level to the desired level. The average volt level for lawn mower batteries is usually 12 volts. More amperage charges the battery faster. Start with two amps and work up to no more than 10 amps. A slow charge is best.
If you find the battery won’t hold a charge, you must replace it with a new battery. You can find 12v lawn mower batteries at your local hardware or automotive store. You will also find batteries at your local lawn mower dealership.
Bring the old battery with you. Most places will charge you a core fee unless you provide them with your old battery. Core fees average $20.
2. Loose Wires and Connections
With the bouncing around and vibration of the riding mower, the cables, wiring, and connections can become loose. The wiring and electrical components will no longer have good continuity.
In addition to looking for loose wires and making sure they are securely attached, you must inspect the connections and wiring for corrosion. Moisture can cause corrosion that will affect continuity.
Remove the corrosion using a baking soda solution (2 cups water to 3 heaping tablespoons of baking soda). Secure any loose wires and connections.
If wires, connections, or terminals are damaged or severely corroded, they must be replaced.
3. Bad Fuse
A fuse is installed on your riding mower to protect the electrical system. You’ll want to check to make sure you don’t have a blown fuse.
If you’re unsure if the fuse is blown, you can check it by placing a multimeter probe on each prong of the fuse to measure resistance. A resistance reading near 0 means your fuse is good. An infinity resistance reading indicates a bad fuse.
When you find a blown fuse, you must replace it with a new fuse. Replace the fuse with the same amperage as the one you are replacing. Do not use a different amperage.
Take your riding mower to your local lawn mower repair shop if you continue to blow the fuse to find and repair the root cause of the problem.
4. Bad Ignition Switch
The ignition key switch can be the culprit when your riding mower won’t turn over after you insert the key and turn it to find nothing happens.
Check the switch using a multimeter to check continuity to determine if the ignition switch is the problem. To do this, look for the prongs marked “B” for Battery and “S” for Starter Solenoid.
Insert the key and turn it to the start position. With the multimeter set to measure resistance, touch one probe to the B prong and the other probe to the S prong.
A good ignition key switch will measure resistance near 0 ohms. A bad ignition key switch will measure infinite resistance and will need to be replaced.
5. Bad Safety Switch
There are several safety switches installed on a riding mower designed to keep the operator safe. These switches prevent a mower from starting if certain events are not met like engaging the brake.
A safety switch can be defective and cause a mower to fail to turn over. Test the switch using a multimeter. You can also temporarily bypass the safety switch to identify a bad switch but only do this for troubleshooting purposes.
Never operate a mower without the safety switch. Never run a mower when a safety switch is bypassed. A safety switch can save you from serious injury and you never know when you’re going to need it.
6. Bad Starter Solenoid
The starter solenoid is an electromagnetic switch that initiates the starter motor to turn over the engine once it is engaged.
The starter solenoid can fail when the internal spring becomes weak or the copper plate begins to corrode. A starter solenoid failure can also be caused by a weak starter, bad battery, or bad ground.
Before you test your starter solenoid, you must have a fully charged battery. Continue testing the solenoid by using the steps to diagnose a bad starter solenoid in “How to Tell Your Lawn Mower Solenoid is Bad”.
7. Bad Starter Motor
Once you have ruled out the battery, cables, wiring, ground, and starter solenoid as being the reason your mower won’t turn over, it’s time to look at the starter. The starter can be removed and tested.
I recommend having your local repair shop specializing in starter and alternator repairs test your starter and rebuild it if possible before throwing a pricey starter at it.
Still Having Problems With Your Riding Mower?
As a lawn mower owner, when you own it long enough, you are going to run into different types of problems. This may include problems where your mower is smoking, cutting unevenly, losing power, not starting, leaking fuel, and more.
Check out this handy guide including charts for common mower problems and solutions:
Common Riding Lawn Mower Problems & Solutions.
If you are unable to fix your mower or don’t want to attempt a more complicated repair, have your local lawn mower dealership or repair shop for assistance.