Base

The operation of an Indicator is explained) in the operation of its circuit. See the circuit referred to for complete operation of an Indicator and the other components that work with it. Only the Gages and Indicators that do not appear in other schematics are described in this Section.

FUEL GAGE DISPLAY

The pointer of the Fuel Gage is moved by the magnetic fields of two coils. The coils are at right angles to each other. Battery voltage is applied to the E coil and the circuit divides at the opposite end of this coil. One path continues to ground through this)e F coil. Another goes to ground through the variable resistor of the Fuel Gage Sender.

When the fuel level is low, the resistance of the Sender is low. A large current passes through the E coil and the Fuel Gage Sender resistor. This pulls the pointer towards E on the scale. When the tank is full, the Sender resistance is high. More current now flows through the F coil, moving the pointer to F on the scale.

With two coils operating the pointer, the Gage is not affected by changes in the voltage of the system.

OIL PRESSURE INDICATOR

The Oil Pressure Indicator comes on to warn the driver when the engine oil pressure is low. Battery voltage is applied to one side of the bulb. A ground path is provided by the Fuel Pump/Oil Pressure Switch/Sender; It closes when the oil pressure is below 27 kPa (4 PSI) and the Indicator bulb lights. After the engine starts and normal oil pressure builds up, the Fuel Pump/Oil Pressure Switch/Sender opens. The Oil Pressure Indicators goes out.

COOLANT TEMPERATURE INDICATOR

The Coolant Temperature Indicator warns the driver of a high coolant temperature. With the Ignition Switch in RUN, BULB TEST or START, voltage from the INDIC Fuse is applied to the Coolant Temperature Indicator. The bulb is grounded through the Coolant Temperature Switch. The switch closes when the coolant temperature exceeds 258°F (126°C). The bulb lights.

SPEEDOMETER/ODOMETER

The Speedometer and Odometer are digital displays controlled by a microprocessor within the Instrument Cluster. The Cluster receives a vehicle speed signal from the ECM in the form of voltage pulses. The frequency of these pulses 'is 4000 pulses per mile. The ECM receives its speed signal from the vehicle speed sensor.