SYSTEM / Electrical System MAIN CIRCUIT The major functions and circuits in the main circuit are as follows. Electric Power Circuit: Supplies all electric power to all electrical systems on this machine. [ Key Switch, Batteries, Fuses (Fuse Boxes, Fusible Links), Battery Relay ] Accessory Circuit Becomes operative when the key switch is turned to the ACC position. Starting Circuit Starts the engine. [ Key Switch, Starter, Starter Relay ] Charging Circuit Charges the batteries. [ Alternator, (Regulator) ] Serge Voltage Prevention Circuit Prevents the occurrence of serge voltage devel- oped when stopping the engine. [ Load Damp Relay ] Pilot Shut-Off Circuit (Key Switch:
ON) Supplies pressure oil to the pilot valve from the pilot pump by the pilot shut-off solenoid valve. Security Lock Circuit Cut electrical current for starting from the key switch according to the signals from external alarm system or monitor unit. Turns the pilot shut-off solenoid valve OFF and blocks the pilot circuit. Engine Stop Circuit (Key Switch: OFF) Stops the engine by using ECM. (MC, ECM) Security Horn Circuit Operate the security horn according to the sig- nals from external alarm system or monitor unit. Working Light Circuit Turn on the work light and cab light. Wiper Circuit Operate the intermittent operation of wiper and the washer. T2-5-2