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15-12
GROUP 15- LIGHTING SYSTEM, HORNS, AND INSTRUMENTS
(288)
PART
15-4
INSTRUMENTS
Section
Page
Section
Page
1
Description and Operation ................ 15-12
3 Removal and Installation ................. 15-14
2 In-Car Adjustments and Repairs ........... 15-14
D
DESCRIPTION AND OPERATION
All of the instruments are elec-
trically operated except the speedom-
eter. Illumination is provided by
lights controlled by a rheostat on the
lighting switch. A front view of the
instrument panel is shown in Fig. 1.
GAUGES
The gauges and lights are shown
in Fig. 7, Part 15-2. Figure 2 shows
the gauge circuits. The upper por-
tion of the instrument cluster con-
tains the speedometer, trip odometer,
turn signal indicators, and the high-
beam indicator. The lower portion
of the cluster contains the fuel gauge,
oil pressure gauge, ammeter, and
temperature gauge.
A constant voltage regulator main-
tains a constant voltage supply to
the fuel gauge, oil pressure gauge,
and temperature gauge circuits.
The constant voltage regulator
(Fig. 3), maintains an average value
FIG.
1-lnstrument Panel
of 5.0 volts at the gauge terminals.
The regulator is temperature com-
pensated for all expected ambient
(surrounding air) temperatures.
FUEL GAUGE
The fuel gauge consists of a send-
ing unit, located on the gas tank, and
a remote register unit (fuel gauge)
mounted in the instrument cluster.
The remote register unit pointer is
controlled by a bimetallic arm and
heating coil. The sending unit is a
rheostat that varies its resistance de-
pending on the amount of fuel in the
tank. The fuel gauge circuit is shown
in Fig. 2.
LOW FUEL LEVEL
WARNING SYSTEM
The low fuel level warning sys-
tem consists of the fuel level sending
unit located on the fuel tank, the
warning relay, and the warning light
incorporated in the fuel gauge. The
warning light will light just before
the fuel gauge pointer indicates
empty and/ or when there are ap-
proximately three gallons of fuel
in the tank.
A thermistor assembly (Fig. 4),
attached to the fuel sender outlet
tube, is kept cool when covered by
gasoline. When the fuel level drops
low enough to expose the thermistor
to air, the thermistor heats up. The
thermistor resistance then drops and
allows current to flow through a
warning signal relay. The relay con-
tacts then close to light the warning
light. The low fuel level warning
system circuit is shown in Fig. 2.
TEMPERATURE GAUGE
The temperature gauge consists of
a sending unit mounted in the cyl-
inder head, and a remote register
unit, (temperature gauge) mounted
in the instrument cluster. The prin-
ciple of operation is similar to the
fuel gauge except that the resistance
of the sending unit is varied by en-
gine temperature. The temperature
gauge circuit is shown in Fig. 2.
OIL PRESSURE INDICATOR
GAUGE
A meter-type oil pressure gauge
is used. The gauge consists of a send-
ing unit on the engine and a remote
register unit in the instrument cluster.
The meter-type gauge circuit is
shown in Fig. 2.
CHARGE INDICATOR GAUGE
The charge indicator used is a
magnetic-loop type ammeter.
TURN INDICATOR
Fig. 1, Part 15-2 shows the turn
indicator wiring diagram.
SPEEDOMETER
The speedometer is connected to
the output shaft of the transmission
by means of a flexible shaft, and a
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