Gauges and Indicators

See the circuit referred to for the complete operation of an indicator and other components that work with it. Only the indicators that do not appear in other schematics are described in this section.

OIL INDICATOR

The Oil Indicator bulb is permanently grounded at G200. The Solid State Module inside the Instrument Cluster gets a signal from the Fuel Pump Switch/Oil Pressure Sender. If the resistance in the sender decreases, indicating low oil pressure, the Cluster will provide voltage to the Oil Indicator, causing it to light.

COOLANT TEMPERATURE INDICATOR

The Coolant Temperature Indicator comes "ON" to warn the driver of high coolant temperature.
With the Ignition Switch in "RUN," "BULB TEST" or "START," voltage from Fuse 17 is applied to the Coolant Temperature Indicator. In "BULB TEST" or "START," the lamp is grounded through the Ignition Switch so that the bulb can be tested. In "RUN," the current path is completed through the Coolant Temperature Switch/Sender. The Coolant Temperature Switch/Sender contains a switch which closes when the coolant temperature exceeds 126°C (258°F) causing the lamp to come "ON."

FUEL GAGE

With the Ignition Switch in "RUN," "BULB TEST" or "START," voltage is applied from Fuse 17 to the Fuel Gage. The Fuel Gage pointer is controlled by varying the Fuel Gage Sender resistance. Voltage is applied from Fuse 17 to the Empty coil of the Fuel Gage and divides into two paths: 1) through the Fuel Gage Sender to ground, and 2) through the Full coil to ground. The Gage pointer is controlled by changes of the sender resistance. When the Fuel Gage resistance decreases, more current flows through the sender and the Empty coil. At the same time, the current through the Full coil decreases.
With two coils operating the pointer, the gage is not affected by changes in the voltage of the system.

COOLANT TEMPERATURE GAGE

The Coolant Temperature Gage applies voltage from CKT 135 to the Coolant Temperature Switch/Sender. The Coolant Temperature Switch/Sender contains a variable resistor. At 40°C (100°F) the resistance is approximately 1365 ohms and at 125°C (260°F) the resistance is approximately 55 ohms. As the resistance of the Coolant Temperature Switch/ Sender decreases, the Coolant Temperature Gage senses a smaller voltage drop across the Coolant Temperature Switch/Sender, indicating higher coolant temperature. As the resistance of the Coolant Temperature Switch/Sender increases, the Coolant Temperature Gage senses a larger voltage drop across the Coolant Temperature Switch/Sender, indicating a lower coolant temperature.

"GATE AJAR" INDICATOR

Voltage is applied at all times to the "GATE AJAR" Indicator from Fuse 2. When the Tailgate is opened, the Gate Ajar Switch closes completing the path to ground which turns "ON" the indicator.