Your mower won’t start and you can’t even get the engine to turn over. There are many different components you’ll need to check in order to get it running again.
A zero-turn lawn mower won’t turn over or crank when the battery is weak; the cables, wiring, or components are loose or corroded; the safety switch is bad; the fuse has blown; the ignition switch is bad, or the starter solenoid or motor has failed.
Take caution when working with the electrical system to avoid injuries and/or electrocution. Consult an experienced mechanic if you are unsure how to perform repairs safely.
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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 Zero Turn Mower Won’t Turn Over
Dead or Bad Battery
The first thing to check on a zero-turn when the engine won’t turn over is the battery. A battery that has a low charge or one that is dead may be the problem.
A fully charged 12-volt battery should give you a reading of about 12.7 volts. If you are getting a lower reading, it’s time to charge the battery.
Test the battery using the steps in the article “5 Things That Are Draining the Life of Your Lawn Mower Battery”. Here, you will find information on items that drain the battery so you can minimize having a dead battery in the future.
Charging a Lawn Mower Battery: Use a battery charger to charge your battery. Before you continue, wear protective gear to protect your eyes and skin.
Follow these steps to charge your battery with a charger:
- Access the battery and terminals. You may need to use a screwdriver to uncover the battery. Do not remove the battery from the casing.
- Connect the charging 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 the battery fails to hold a charge it must be replaced with a new battery. You can purchase a new battery at your local lawn mower dealership, hardware store, or automotive store.
Don’t forget to bring the old battery with you. You will most likely be charged a battery core fee if you don’t provide the store with the old battery when purchasing a new one.
Loose or Corroded Wires and Connections
There is usually quite a bit of bounding and vibration when mowing with a zero-turn. This can cause wires and connections to come loose.
Loose or corroded electrical components may be the reason your mower won’t start because of a break in continuity.
Check the connections to make sure they are securely in place. Remove any corrosion you find using a baking soda solution (2 cups water to 3 heaping tablespoons of baking soda). Secure any loose wires and connections.
If you find wires, connections, or terminals are damaged or severely corroded, replace them with new components.
Bad Fuse
You will find a fuse(s) used on a lawn mower to help protect the mower’s electrical system. The fuse can blow due to a short or overload.
If you are unsure you have a blown fuse, 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.
Replace a blown fuse with the same amperage as the fuse you are replacing.
If you continue to blow fuses, you should bring your mower to your local mower dealership or lawn mower repair shop to troubleshoot the root cause.
Bad Ignition Switch
The ignition key switch can be the culprit to your zero-turn starting problem.
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.
Bad Safety Switch
Zero-turn mowers utilize an OPC (operator presence control) system as a safety measure to assist with keeping the operator safe.
This is a system that includes safety switches to prevent a mower from starting if certain events are met like engaging the brake.
A safety switch can be defective and cause your mower to fail to turn over. Test the safety 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.
Bad Starter Solenoid
A starter solenoid is an electromagnetic switch that, when engaged, initiates the starter motor to turn over your engine.
The starter solenoid can go bad when the spring becomes weak or the copper plate begins to corrode. A weak starter, bad battery, or bad ground can also cause it to fail.
Before you test your starter solenoid, you must have a fully charged battery. Continue testing it by using the steps to diagnose a bad starter solenoid in How to Tell Your Lawn Mower Solenoid is Bad.
Bad Starter Motor
Once you have ruled out the battery, cables, wiring, ground, and starter solenoid as being the reason your zero-turn 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 that specializes in starter and alternator repairs test your starter and rebuild it if possible before just throwing a pricey new starter at your mower.
Still Experience Problems with Your Zero Turn Mower?
Many different types of problems can develop in a mower. It doesn’t matter what brand you own.
While some mowers are built with stronger materials, bigger filters, better engines, and tougher spindle housings, they are all going to break down and cause issues at some time. Some may just not develop problems as quickly as others.
I put together a guide with common things that go wrong on zero-turns. In this guide, you will find a list of causes and solutions for a mower dying, smoking, vibrating, not starting, having cutting issues, and more.
Check out my guide at Common Zero Turn Mower Problems: How to Fix Them
If you still can’t find the solution to your problem or you don’t feel comfortable troubleshooting or repairing your mower, it is best to have an experienced mechanic check out your mower.
You can visit your local dealership that provides repair support for your brand mower. You may also find a lawn mower repair shop with experienced small engine mechanics.