My Cub Cadet Lawn Tractor Will Not Turn Off With a Key

Ignition Switch

• The ignition switch for your Cub Cadet mower starts the electrical process needed for engine combustion. When the key is turned to the start position, it’s commanding the ignition switch to generate a charge by forcing two electrical poles inside it to connect. Normally, the poles would disconnect when the key is turned to the “off” position, effectively severing the combustion processes and turning off the engine. However, a damaged key receptacle may not allow that. A shorted or otherwise faulty switch won’t allow the two poles to disconnect. It’s easier to replace the switch than to repair it because of its size.

Magneto

• The magneto is the next step in the ignition process. Magnetos have two coils- one wound with thick, metal wire and another, more smaller and more compact coil. When the magneto receives the ignition switch’s “on” command, a flywheel spins a magnet past an armature connected to the thick coil, creating an electrical charge. The charge passes from the thick coil to the smaller coil once a circuit breaker is tripped. The smaller coil amplifies the charge, so it generates enough electricity to cause a spark to release through the spark plug. Coil damage, magnet problems or a broken circuit breaker in the magneto can keep your Cub Cadet’s motor running after the key is turned off.

Wire Damage

• Examine your Cub Cadet mower’s starting system for obvious wire damage. Look for exposed wiring caused by tears or breaks in the wires. Also idenitfy any unusual crimping or bends in the wires that may cause intermittent signals throughout the system. Other surrounding electrical wiring may be damaged and cause arcing to your ignition system.

Negative and Ground wires

• Look for negative and ground wires throughout the starting system. Check at the ignition switch, magneto, and spark plug areas. Negative and ground wires prevent electricity from leaving the ignition system. Negative wires are black and sometimes have a “minus” sign printed on them, while separate ground wires have a dissimilar metal on the end and are attached to another part of the engine. If either of these are disconnected, the electrical charge could be arcing, causing the ignition system to continue running after you disengage it.