Yanmar 1GM10, Shop Manual, Page: 203 / 240

ELECTRICAL SYSTEM 197
Coolant temperature
sender
I
Positive
.
To
nsors
I
WARNING LAMPS
Engines covered by this manual are equipped with an
instrument panel that has three warning lamps. The warn-
ing lamps illuminate to indicate high coolant temperature,
low oil pressure or insufficient charging current.
Coolant and Oil Pressure Warning Lamps
1. To check the circuit for the coolant or oil pressure
warning lamp, detach the lead from the coolant tempera-
ture or oil pressure sender.
2. With the key switch ON, ground the sender lead. The
warning lamp should come on.
3. To determine if a bulb is defective, substitute a good
bulb. All warning lamps use the same type of bulb.
Charging System Warning Lamp
The warning lamp for the charging circuit should illu-
minate when the key switch is ON and the engine is not
running, or when there is a malfunction in the charging
circuit.
1. To check the circuit for the charging system warning
lamp, detach the lead
the L terminal on the alterna-
tor.
2. With the key switch ON, ground the detached lead.
The charge system warning lamp should come on.
3.
To determine if the charging system bulb is defective,
substitute a good bulb. All warning lamps use the same
type of bulb.
4. If a good bulb does not light, check the charging sys-
tem as described in Chapter Two.
ALARM BUZZER
The alarm buzzer provides an audible warning in addi-
tion to the coolant and oil pressure warning lamps. Two
types of alarm buzzers are used: a buzzer with two leads
and a buzzer with multiple leads. Note the terminal loca-
tions in Figure 28 for the buzzer equipped with multiple
leads.
1. Check the alarm buzzer while it is installed.
a. Detach the lead from the coolant temperature or oil
pressure sender.
b. With the key switch ON, ground the sender lead.
The alarm buzzer should come on.
2. Check the alarm buzzer with all leads disconnected
from the buzzer or with the buzzer removed from the in-
strument panel.
a. On the buzzer with multiple terminals, note the ter-
minal locations in Figure 28.
b. Connect a 12-volt battery to the terminals as fol-
lows: Connect a positive battery lead to positive
buzzer terminal. Connect the negative battery lead
to each of the remaining buzzer terminals. The
buzzer should sound; if it does not, replace the
buzzer.
TACHOMETER
Some engines may be equipped with a tachometer. A
sensor located on the clutch housing (Figure 29) provides
an electrical signal that drives the tachometer. The elec-
tromagnetic sensor counts the teeth on the flywheel ring