Cooling Water Temperature Alarm - Yanmar 3YM30 Service Manual

12. Electrical System
Inspection
Problem Inspection Item
Lamp not 1. Oil pressure lamp
illuminated when
main switch set
to ON.
2. Operation of oil
Lamp not 1. Oil level low.
extinguished
while engine
2. Oil pressure low.
running.
3. Oil pressure
4. Wiring between

12.7.2 Cooling water temperature alarm

A water temperature lamp and a water temperature switch (thermo switch), backed up by an alarm in the
instrument panel, are used to monitor the temperature of the engine cooling water. A high thermal
expansion material is set on the end of the water temperature unit. When the cooling water temperature
reaches a specified high temperature, the contacts are closed, and an alarm lamp and buzzer are
activated at the instrument panel.
Fresh water pump
Operating
temperature
Electric capacity
Response time
I.D. color
Tightening torque
Inspection method
(1) Visual inspection.
blown out. (2) Lamp not illuminated even
Lamp illuminated when checked as
pressure switch. described in (2) above.
Stop engine and check oil level with
dipstick.
Measure oil pressure.
Switch faulty if abnormal at (1) and
faulty. (2) above.
Cut the wiring between the lamp
lamp and oil and switch and wire with separate
pressure switch wire.
faulty.
Water temperature
switch
ON 93-97 deg. C
DC 12V, 1A
within 60 sec.
Black
23.54-31.38 N•m
(2.40-3.20 kgf-m)
when main switch set to ON
position and terminals of oil
pressure switch grounded.
Pilot lamp
Water temperature unit
(Water temperature alarm circuit)
198
Corrective action
Replace lamp.
Replace oil pressure
switch.
Add oil.
Repair bearing wear
and adjust regulator
valve.
Replace oil pressure
switch.
Repair wiring harness.
Fuse Main switch
Alarm buzzer
Battery
54.3 mm
M16 x 1.5
Black