Warning Devices - Yanmar 4LHA-HTP Operation Manual

Chapter 9 Electrical System

6. Warning Devices

6. Warning Devices
6-1 Oil pressure alarm
If the engine oil pressure is below 0.0098 ~ 0.0294 (0.1 -
0.3) MPa (kgf/cm), with the main switch in the ON position,
the contacts of the oil pressure switch are closed by a
spring, and the lamp is illuminated through lamp — oil
pressure switch — ground circuit system. If the oil
pressure is normal, the switch contacts are opened by
the lubricating oil pressure and the lamp remains off.
Pilot lamp
(Oil pressure alarm circuit)
Oil pressure
Oil pressure switch
Spring
Problem
Lamp not illuminated when Lamp not illuminated when
main switch set to ON main switch set to ON
Lamp not extinguished Lamp not extinguished Lamp not extinguished Lamp not extinguished
while engine running while engine running while engine running while engine running
Main switch
Fuse
Battery
Contacts
Oil pressure
Inspection item
1. Oil pressure lamp
blown out -
2. Operation of oil pressure
switch
1. Oil level low
2. Oil pressure low
3. Oil pressure faulty
4. Wiring between lamp and oil
pressure switch faulty
Part No.
Rated voltage
Operation pressure
Lamp capacity
Inspection method
(1) Visual inspection
(2) Lamp not illuminated even
when main switch set to ON
position and terminals of oil
pressure switch grounded
Lamp illuminated when checked
as described in (2) above
Stop engine and check oil
level with dipstick
Measure oil pressure
Switch faulty if abnormal at (1)
and (2) above
Cut the wiring between the
lamp and switch and wire with
separate wire
9-37
4LHA Serie:
Oil pressure switch
124060-39451
12V
0.0098-0.0294(0.1-O.SlMPalkgf/cm')
5W
Corrective action
Replace lamp
Replace oil pressure switch
Add oil
Repair bearing wear and
adjust regulator valve
Replace oil pressure switch
Repair wiring harness