Temperature Gauge

The pointer of the Temperature Gauge is moved by the magnetic fields of two coils, the 100° F Coil and the 260° F Coil. The two coils are oriented at right angles so that the magnetic fields interfere with each other. Battery voltage is available from GAUGES Fuse 4 through the PNK (39) wire to the Instrument Cluster when the Ignition Switch is in RUN or START. Current flows through the 100° F Coil which places the pointer at 100° F (low temperature) if there is little current through the 260° F Coil. If the current through the 260° F Coil is high, then the pointer moves toward the 260° F (high temperature) indication.

The current that passes through the 260° F Coil has two paths to ground. Some of the current can pass through the fixed resistance of the 100° F Coil and to Ground G101 through the BLK/WHT (451) wire. The rest of the current will go to ground through the variable resistance of the temperature sensor. The Engine Coolant Temperature Gauge Sensor produces a resistance of approximately 1305 ohms when the temperature is 100° F (40° C). With this high resistance, more current flows through the 100 Coil and the pointer moves toward 100. The sensor's resistance is approximately 61.9 ohms at 245° F (118° C). With this low resistance, more current passes through the temperature sensor and not the 100 Coil. The pointer moves toward 260.

A high temperature condition causes the CHECK GAUGES lamp to light. The setpoint is at approximately 61.9 ohms or 245° F (118° C).

The Temperature Gauge's accuracy is adequate for normal operator usage because it provides a reasonably accurate indication of engine coolant temperature from which sudden or long term changes may be identified. The sensing element's response is non-linear over the operating range and this limits accuracy. The gauge accuracy specification is for 3.5 degrees (angular) at 260° F and for 7 degrees at 100° F. Gauge accuracy is not affected by changes in battery voltage.