Trouble Starting or Engaging John Deere Lawnmower Blades

A worn or stretched mower deck belt, a belt that has come off the pulleys, a malfunctioning PTO switch, a faulty clutch, a weak battery, a faulty safety switch, or a blown fuse might prevent the John Deere lawn mower blades from engaging or turning.

When working on your John Deere, be sure to exercise extreme caution. Take out the key and disconnect the wire from the spark plug. Stop any motion before proceeding.

John Deere Mower Blades

Problems Starting or Engaging John Deere Mower Blades

Deck Belt Fastened on a John Deere Lawn Mower

If your mower blades are stuck and not turning, the problem may be the belt on the mower deck. The belt that drives the mower blades can wear out and stop working.

Deck belts made by John Deere that are cracked, frayed, or have a glazed look have seen better days and are considered worn or bad. As a result of wear, a deck belt may fall into the pulley grooves.

If the belt is worn, you should get a new one. When the belt shows symptoms of wear, you should replace it regardless of whether this is the primary cause of your blades not engaging.

Blade speed is determined by the tension of the belt around the pulleys. Grass needs to be lifted and cut uniformly, which can only be done with a fast blade speed that creates suction under the deck.

A John Deere Mower Deck Had Its Belt Come Off Its Pulleys.

If the belt has come unlatched from the pulleys, it will no longer be able to rotate them and so propel the mower’s blades. Check for a missing spring, worn tensioner arm, stretched belt, damaged pulley, and a worn belt.

John Deere Idle Arm and Spring Wear

The idler pulleys are kept in place by a tensioner arm and spring. The pulley and spring are often located on opposite sides of the bracket on mower decks.

Either the spring or the hole in the bracket where it is attached can wear out over time. Because of this, the belt may get untied and start to vibrate between the pulleys.

Damaged Bearing in a John Deere Pulley

Each pulley has a bearing inside of it. After some time, the pulley’s bearing may wear out, causing it to no longer sit perpendicular to the mower’s deck. As the pulley’s bearing wears, it will get looser and cause it to wobble.

It’s possible that the pulley’s deck mounting on one side is not level with the other. The deck belt may become dislodged from the pulley as a result of the increased rotation.

A faulty bearing will cause the pulley to move, and you can also locate a failed bearing by spinning the pulley very gently by hand. Check for squeaks or other noises coming from the bearing to determine if it is failing.

If the bearing in a pulley assembly is worn out, you should replace the whole thing. Some idler pulleys may be serviceable by replacing the bearings.

The John Deere Mower’s Defective PTO Switch (Electric Clutch)

The PTO switch is a knob on most lawn mowers that activates the clutch using battery electricity. The inability to turn on the blades is a direct result of a faulty switch.

Verify that the switch has continuity. Substitute a break in continuity for a toggle switch.

John Deere Mower with a Faulty Clutch

When the drive belt is engaged, power from the engine is transferred to the blades via the PTO clutch. When a worn or broken clutch can’t turn the blades, it needs to be replaced.

Read A Look at Lawn Mower Clutches for more information about clutches.

John Deere Clutch Cable Frayed (Manual Clutch)

Those John Deere mowers that require manual engagement of the clutch will have a clutch lever and cable.

Be that the clutch is being engaged and that the clutch lever, cable, spring, bushings, and linkages are in good shape.

All broken or worn items must be replaced.

John Deere Mower Has a Weak Battery

The battery is what powers a John Deere electronic clutch. The clutch solenoid cannot activate the mower blades when the battery is too weak to supply enough power.

Use a multimeter to determine the battery’s current state of charge. The voltage of a fully charged 12-volt battery should be around 12.7 volts.

If the readout is lower than this, it’s time to charge the battery. In 5 Things That Are Draining the Life of Your Lawn Mower Battery, you’ll uncover the most common causes of a dying battery and how to fix them.

To recharge a John Deere battery, you should use a dedicated battery charger. It is imperative that you safeguard your eyes and skin from any electrical shock before proceeding. To use a charger on your battery for your riding mower or zero-turn, do as follows:

  • Discover where the battery and connections are located. The battery compartment may require removal of screws. The battery is either underneath the seat or in the engine compartment. Keep the battery inside its case at all times.
  • Start by plugging in the positive cable to the battery charger. The plus sign cable, or the red cable, is this one. Connect the wire to the terminal labeled “+” on the battery.
  • Don’t forget to connect the negative end of the battery cable to the negative battery terminal. This is the negative-sign cable, sometimes known as the black cable.
  • For fear of electric shock, avoid touching anything that isn’t covered in rubber.
  • The voltage and current output of the charger can be adjusted to suit your needs. Lawn mower batteries typically have a voltage of 12 volts. The rate at which a battery is charged is sped up by a boost in amperage. Initiate with 2 amps and increase to no more than 10 amps as needed. Charging slowly is preferable.

If the battery isn’t holding a charge, you’ll need to get a new one. The batteries for your lawnmower’s 12-volt system can be found at any hardware or auto parts store. Your neighborhood lawn equipment retailer might also stock batteries.

Make sure to bring along the dead battery. Unless you return the old battery, most stores will charge you a core fee. On average, basic charges amount to $20.

John Deere Mower’s Faulty Safety Switch

To further ensure the operator’s safety, safety switches are installed. The seat switch is one example of a safety feature like this.

When the driver is seated, he or she will activate this switch. The mower’s blades won’t stop spinning unless the seat switch is activated.

A John Deere lawn tractor was what I used to mow my lawn with when I was a kid. Since the terrain was not flat, every time I hit a bump the mower deck would turn off because the seat switch would no longer be engaged after I had bounced off.

When the seat switch is malfunctioning, the mower blades won’t start spinning since it doesn’t know there’s a person sitting in there.

If you suspect a faulty seat switch, you can test it with a multimeter or temporarily disable the safety feature. In order to avoid injury, never start a mower without first installing the safety switch.

Make sure that all of the safety switches on your machinery are functional at all times.

A John Deere Lawnmower Fuses Out

The electrical circuitry of a John Deere lawn mower is shielded by a fuse. It’s possible that a fuse has blown, leaving you without electricity.

Fuse replacement requires usage of a fuse of the same amperage rating. If the fuses keep blowing, I suggest taking the mower to a John Deere service store or a lawn mower repair business so they can investigate the problem.

Is Your John Deere Mower Still Giving You Trouble?

If you buy a John Deere mower, you may expect to deal with a wide range of issues during the course of its service life. For example, it may have trouble getting started, may shut off unexpectedly while mowing, may vibrate excessively or cut unevenly, or may simply stop moving.

I compiled a useful guide for diagnosing issues with your John Deere mower so you can figure out what’s wrong with it. Please refer to “Common John Deere Lawn Mower Problems and Solutions” for help.