Temperature Gauge: Description and Operation

Coolant Temperature Gauge:

The coolant temperature gauge circuit reads engine coolant temperature through the use of an engine mounted coolant temperature sensor (thermistor). The voltage is sent from the fuse block through the instrument cluster to the coolant temperature sensor (thermistor) and to ground. As coolant temperature increases, thermistor resistance decreases and when coolant temperature decreases thermistor resistance increases. The display of the correct temperature reading is dampened slightly upon start-up (cycling of ignition) and will stabilize after approximately 12 seconds. The sensor resistance range is from 320.49 ohms at 50°C to 36.095 36.95 ohms at 130°C.

When the ignition is returned to the OFF position the coolant temperature gauge will return the pointer to mechanical zero position or C. If any time a coolant
temperature sensor error is recognized for more than 8 seconds by the gauge the pointer will return to mechanical zero or C. If the sensor signal is then recognized as being intact for more than 4 seconds the gauge will resume operation as in a start up (cycling of ignition) mode (will take approx. 12 seconds to stabilize).

The coolant temperature gauge will provide accurate readout with operating voltage anywhere between 9 and 16 volts. The coolant temperature gauge accuracy tolerance is accurate within 4.4 degrees of needle sweep. The gauge can also tolerate a 24 volt over voltage situation for up to 60 seconds and a reverse battery voltage situation of -12 volts for 60 seconds with no lasting damage to the unit.