SYSTEM / Electrical System PILOT SHUT-OFF CIRCUIT (KEY SWITCH: ON) 1. When the pilot shut-off lever is turned to the UNLOCK position, the pilot shut-off switch is turned ON. 2. Electrical current from fuse #4 flows to the ground through the pilot shut-off relay and pilot shut-off switch so that the pilot shut-off relay is excited. 3. At the same time, the starter cut relay is con- nected to the ground circuit. 4. When the pilot shut-off relay is excited, the ground in pilot shut-off solenoid valve is con- nected to the ground through the pilot shut-off relay and security relay. 5.
Therefore, the pilot shut-off solenoid valve is turned ON, pressure oil from the pilot pump is routed to the pilot valve. 6. When the key switch is turned to the START po- sition, the starter cut relay is excited. 7. When the starter cut relay is excited, the circuit between terminal ST in the key switch and ter- minal S in starter relay is blocked. 8. Therefore, when the pilot shut-off lever is in the UNLOCK position the key switch is turned to the START position, the engine does not start. T2-5-16