Hitachi ZW180 Technical Manual page 113

Engine Oil Low Pressure Indicator Control
Purpose: To light the engine oil pressure indicator on
monitor unit in order to inform the pressure
lowering in engine lubricant oil to the
operator.
Operation:
1. When the engine lubricant oil pressure becomes
lower than the normal range, ECM excites the
engine oil pressure relay. Therefore, terminal 1-8
of the monitor unit is grounded.
2. When terminal 1-8 of the monitor unit is grounded,
the monitor unit lights the engine oil pressure
indicator.
Engine Oil Low
Pressure Indicator
Stop Indicator
SYSTEM / ECM System
From Fuse #9 of
Fuse Box B
Monitor
Unit
Diode H
1-8
3. When the engine lubricant oil pressure returns to
the normal range, ECM demagnetizes the engine
oil pressure relay. Therefore, terminal 1-8 of the
monitor unit is disconnected form the engine.
4. When terminal 1-8 of the monitor unit is
disconnected form the engine, the monitor unit
turns off the engine oil low pressure indicator.
NOTE: The monitor unit lights the stop indicator as
well as the engine oil pressure indicator.
Engine Oil
Pressure Relay
T2-2-7
ECM
48
T4GD-02-02-006