Shibaura ST330, Workshop Manual

Page: 207 / 250

196
13
）
DIODE FOR ALTERNATOR
Description
This diode is as same as “9 ） DIODE OF HST CIRCUIT “ except installed position.
It is installed near alternator on the wiring harness.
14
）
ENGINE COOLANT
TEMPERATURE
SENDING UNIT
(385720011)
Description
The engine coolant temperature sendin g unit,
1, is located on th e left side of th e
thermostat h ousing.
The sendin g unit regulates a v ariable
resistan ce to ground, which tran slates to
movement of th e temperatu re g auge o n th e
instru men t pan el. The sending unit decreases
ground resistance as coolant temperatu re
rises, causin g th e temp erature gaug e to rise.
Removal
1. Disconn ect the negativ e (-) battery cable
from th e b attery.
2. Drain t he eng in e coolant from th e
radiato r.
3 . Disconnect the main wiring harness
termin al, 2 , fro m the coolant
temperatu re sending unit, 1.
4. Remove the send ing unit, 1, fro m th e
engin e.
Testing
WARNING:
Do n ot perform sending u nit test with tra ctor
engine running, contact with moving parts
will cause b odily inju ry.
NOTE:
･ Engine paint must be removed from sending
unit body or the ohmm eter will indicate a
false reading when th e o hmmeter test lead
is touched to sending un it b ody.
･ The resistance ra ting is measured on th e
special circuit for correctly.
1. Using an ohmmeter, touch one test lead
to th e send ing unit terminal. Tou ch th e
other test lead to th e sending unit body.
2. Observe th e oh mmeter for resistance
readings at different engin e operating
temperatures. If resistan ce is too h igh,
th e send ing unit is defective and needs
replaced .
545Y
Reference value
Coola nt
Tempera ture
Sending U nit
Resistance
35 ℃ 670.0 ± 80 o hms
80
℃
118.0
±
6 ohms
105
℃
54 .5
±
2 .7 ohms
115
℃
42 .0
±
2 .5 ohms
Installation
1 . Install the sending unit, 1, into th e
eng ine.
2 . Connect the main wiring h arn ess
terminal, 2 , to the sending un it, 1.
3 . Fill the radiato r with th e recommended
coolant mix ture.
4 . Connect the neg ativ e (
－
) battery cabl e
to the battery.