Instrument Panel, Gauges and Warning Indicators: Description and Operation

OIL PRESSURE INDICATOR (BASE)

With the ignition switch in the "ON" position, Battery voltage is applied through Fuse C-7 to the Oil Pressure indicator. When engine oil pressure falls below 25 kPa (4 psi), the OIL PRESSURE SWITCH closes. With this switch closed, a ground path is provided to the Oil Pressure Indicator and the bulb lights.


OIL PRESSURE GAGE (GSi)

When the ignition switch is in the "ON" position, Battery voltage is applied from Fuse C-7 to the Oil Pressure Gage. When oil pressure is high, resistance in the OIL PRESSURE SENDER is low, allowing more current to flow through the coil in the Oil Pressure Gage to ground through the OIL PRESSURE SENDER. As more current passes through the Oil Pressure Gage, the coil creates a magnetic field pulling the indicator toward the "110" position.

FUEL GAGE

The pointer of the FUEL GAGE is moved by the magnetic fields of two coils. The coils are at right angles to each other. With the ignition switch in the "ON" position, Battery voltage is applied through Fuse C-7 to coil F of the Fuel Gage. The circuit divides at the ground side of the coil. One path to ground is through coil E and the other path seeks a ground through the variable resistor in the FUEL TANK SENDER.

When fuel level is low, resistance in the FUEL TANK SENDER is high. Since current will always seek the path of least resistance, current will flow through coil F and coil E to ground at the negative (-) BATTERY Terminal. The length of coil E's winding is twice the length of coil F's winding. Therefore, the magnetic field generated by coil E is twice as strong as the magnetic field generated by coil F and the pointer will be pulled to the "E" position.

As fuel level increases, resistance in the FUEL TANK SENDER decreases. Since current will always seek the path of least resistance, more current will begin to bypass coil E and travel directly to ground through the FUEL TANK SENDER. Under these conditions, coil F's magnetic field becomes stronger than coil E's magnetic field and the pointer moves toward the "F" position.

COOLANT TEMPERATURE GAGE

The pointer of the Coolant Temperature Gage is moved by the magnetic fields of two coils. The coils are at right angles to each other. With the ignition switch in the "ON" position, Battery voltage is applied through Fuse C-7 to coil H of the Coolant Temperature Gage. The circuit divides at the ground side of the coil. One path to ground is through coil C and the other path to ground is through the variable resistor in the COOLANT TEMPERATURE SENSOR.

When coolant temperature is low, resistance in the COOLANT TEMPERATURE SENSOR is high. Since current will always seek the path of least resistance, current will flow through coil R and coil C to ground at the negative (-) BATTERY Terminal. The length of coil C's winding is twice the length of coil M's winding. Therefore, the magnetic field generated by coil C is twice as strong as the magnetic field generated by coil H and the pointer will be pulled to the "C" position.

As coolant temperature increases, resistance in the COOLANT TEMPERATURE SENSOR decreases. Since current will always seek the path of least resistance, more current will begin to bypass coil C and travel directly to ground through the COOLANT TEMPERATURE SENSOR. Under these conditions, coil M's magnetic field becomes stronger than coil C's magnetic field and the pointer moves toward the "H" position.


TACHOMETER

While the engine is running, the Tachometer displays engine speed in revolutions per minute (rpm). Electrical pulses are taken from the ignition system and sent to the Tachometer. The Tachometer responds to the frequency of these electrical pulses, which increase or decrease with engine speed.


VOLTMETER (GSi)

With the ignition switch in the "ON" position, Battery voltage is applied to the Voltmeter through Fuse C-7. The Voltmeter is permanently grounded at the negative (-) BATTERY Terminal. As system voltage increases, the magnetic field generated by the coil in the Voltmeter becomes stronger pulling the indicator toward the "16" position. The purpose of the diode next to the VOLTMETER in the INSTRUMENT PANEL CLUSTER printed circuit is to provide a large forward current to the Voltmeter.