When I turn the key the mower does not do anything. But if I jump the soloind switch it will start. What can be the problem.

Thank you
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Hi, The fuse is an obvious place for failure. Additionally, the two most failed mechanical devices in the wiring are the solenoid and the key switch. Battery voltage must reach the switch which a blown fuse would prevent. The switch must pass this voltage to the solenoid trigger circuit which a bad switch will not. The solenoid must have the activated trigger coil throw the high current circuit by the magnetic field created within its trigger coil. All of this assumes a good ground.
If you would like to provide the model number(under the seat) I can possibly provide a parts breakdown with the schematic.
Peace,
Clarke