SYSTEM / Electrical System SECURITY LOCK CIRCUIT 1. When the external alarm signal or password in- put error signal from ICF is input to the monitor unit, terminal #A4 is connected to the ground in- side the monitor unit. 2. Therefore, the security relay and starter cut relay are excited. 3. When the security relay is excited, the ground circuit in pilot shut-off solenoid valve is blocked and the pilot shut-off solenoid valve is turned OFF. 4. Therefore, pressure oil which flows to the pilot valve from the pilot pump is blocked by the pilot shut-off solenoid valve. 5.
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. 6. Therefore, when the key switch is turned to the START position, the engine does not start. T2-5-18