Temperature Gauge

The pointer of the temperature gauge is moved by the following components:
^ The 38°C (100°F) Coil
^ 93°C (260°F) Coil

The 2 coils are oriented at right angles so that the magnetic fields interfere with each other. Battery voltage is available from the GAUGES Fuse 4 through the CKT 39 (PNK) wire to the instrument cluster when the ignition is in the RUN or START position. Current flows through the 38°C (100°F) coil which places the pointer at 38°C (100°F) (low temperature) if there is little current through the 93°C (260°F) coil. The pointer moves toward the 93°C (260°F) (high temperature) indication if the current through the 93°C (260°F) is high.

The current that passes through the 93°C (260°F) coil has 2 paths to ground. Some of the current can pass through the fixed resistance of the 38°C (100°F) coil and to Ground G101 through the CKT 451 (BLK/WHT) 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 38°C (100°F). With this high resistance, more current flows through the 38°C (100°F) coil and the pointer moves toward 38°C (100°F). The sensor's resistance is approximately 61.9 Ohm at 118°C (245°F). With this low resistance, more current passes through the temperature sensor and not the 38°C (100°F) coil. The pointer moves toward the 93°C (260°F).

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

The accuracy of the temperature gauge is adequate for normal operator usage because the temperature gauge provides a reasonably accurate indication of the engine coolant temperature from which sudden or long term changes may be identified. The response of the sensing element is non-linear over the operating range. The non-linear response of the sensing element limits the accuracy of the temperature gauge. The gauge accuracy specification is for the following measurements:
^ 3.5° (angular) at 93°C (260°F)
^ 7° (angular) at 38°C (100°F)

The gauge accuracy is not affected by changes in the battery voltage.