The starter solenoid on a lawn mower acts like an electronic switch. When the ignition key for the mower is turned to the "start" position, the solenoid engages and sends electrical current from the battery to the starter. When the solenoid fails, there is no way to repair it, and it must be replaced.
Place the mower on a level surface. Open the hood of the mower and remove the negative battery cable by unscrewing the the cable nut with your ratchet and the correct socket.
Trace the positive battery cable to the solenoid. The first place the positive battery cable connects to leading away from the battery is the solenoid.
Disconnect or unplug each wire connected to the solenoid. In some cases, they will just be wiring harness plugs that can be pulled apart. In other cases, connecting nuts on electrical posts must be loosened before the wires can be taken off. Mark each wire removed by wrapping a piece of masking tape around it, and using a pen, label the post it came off. For example, a wire removed from the upper left post can be labeled "TL" for "top left."
Unscrew the bolts that anchor the starter solenoid to the lawn mower chassis. Take out the old solenoid.
Bolt in the new solenoid exactly the way the old one came out. Attach the wires to their correct electrical posts as marked on the masking tape, reconnect the negative battery cable and close the hood.
Turn off all lights and other electronic devices when the mower is not in use.
Replace the battery before the recommended replacement date as all batteries lose power over time. As the battery ages, it proves more difficult to regain or retain a charge.
Use the adjustable wrench to remove battery cables from the terminals if the lawn mower is going to be stored for a long time. Even with nothing turned on, the cables draw small amounts of power from the battery. If the cables are left connected during a long storage period, you may encounter a dead battery when trying to start the mower.
Press the Cub Cadet brake pedal down with your foot and push down on the parking lever to set the parking brake. Hold the lever in place while you remove your foot from the brake pedal.
Remove the black battery cable by loosening the bolt holding it to the Cub Cadet battery terminal using an adjustable wrench. Loosen the bolt on the red cable and remove it from the battery terminal.
Dispose of the used Cub Cadet battery at an auto parts store, or contact your city or municipality for an approved disposal location.
Install the replacement battery in your Cub Cadet. Attach the red battery cable to the positive battery terminal first, and then attach the black cable to the negative battery terminal. Make sure the bolts are tight and the connections to the terminals are secure.
Raise the lawn tractor hood to the fully opened position. Slide the terminal covers off the battery terminals if your lawn tractor uses covers.
Loosen the negative black cable clamp and the positive red cable clamp, using a 7/16-inch open end wrench. Lift the black cable off of the battery terminal first and then lift the red cable off the opposite terminal.
Lift the old battery straight out of the battery compartment. Set the new battery inside the compartment.
Slide the positive red cable clamp over the positive battery terminal. The positive terminal has a “+” stamp on the top of the terminal. Tighten the red cable clamp to the terminal with the wrench.
Attach the black cable clamp to the negative terminal. Tighten the clamp on the end of the cable with the wrench. Slide the terminal covers over each of the battery terminals. Close the hood.
Park the Sears Craftsman mower on a level surface and pull the ignition key out of the ignition. Open the lawn mower hood to the fully open position, if your battery is under the hood. Some Sears Craftsman mowers have the battery under the operator's seat. Lift the seat forward to access the battery.
Loosen the black battery cable clamp on the battery with an open-end wrench. Pull the black battery cable off the battery terminal. Loosen the clamp on the red battery cable and pull the red battery cable off the battery. Grab the battery on two sides and lift the battery out of the battery compartment.
Place a replacement battery inside the battery compartment. Position the cable clamp on the red cable over the "+" terminal on the battery. Tighten the clamp with the wrench.
Push the black cable clamp over the "-" terminal on the battery and tighten the clamp with the wrench. Lower the operator's seat or the lawn mower hood, depending on the location of the battery.