Brute-force Starter Test

If the engine won't crank when you turn the key, first be sure one of the interlocks isn't engaged.  For tractors with a clutch, the clutch must be fully depressed.  The PTO needs to be disengaged.  Tractors with hydrostatic transmissions must be in neutral.

Once you have verified that you haven't created the problem by (for example) having the PTO engaged, you want to determine if the problem is associated with the battery, battery cables, and starter or with the contol signal that energizes the starter.

Brute-force Starter Test.  Refer to this starter diagram:
Starter diagram


On Kioti tractors, the starter is located low on the left side near the back of the engine.  The starter case is connected to battery negative through the engine block.  The battery positive cable is connected directly to the "big" outside terminal of the solenoid.  The other large terminal feeds power to the starter when the solenoid is energized.  In addition, there is a small spade terminal on the top of the solenoid.  When this small terminal is energized with +12v, the solenoid  closes a heavy-duty contactor that provides battery power to the starter motor while simultaneously forcing the starter motor's pinion gear to engage the flywheel gear. 

If you measure the voltage (to chassis ground) at the big outside terminal, it should be the same as the battery voltage.  This is illustrated in the above figure. 

The Acid Test:  If you use a piece of wire to jump (temporarily connect) the small solenoid terminal to the big outside solenoid terminal, the starter should engage the flywheel and crank the engine.  The key switch position does not matter except the engine could start if the switch is on; so be sure the transmission is in neutral.  This is equivalent to turning the key to the start position but it bypasses all of the logic and safety interlocks in the normal start circuit. 

Interpreting the result: If the engine cranks normally during this test, the battery, battery cables, and starter are OK so it's time to troubleshoot the start logic circuits (interlocks, key switch, relay, etc.) .  But if the engine fails to crank or cranks slowly investigate the battery, cables, and starter.