XJ-6 L6-4.0L (1991)
Coolant Temperature Sensor/Switch (For Computer): Description and Operation
The coolant temperature sensor, located on the thermostat housing, is a negative temperature coefficient (NTC) thermistor. NTC means that the
resistance of the thermistor decreases as the sensed temperature increases. Pin 1 of the sensor is connected to ground through the ECM. The ECM
applies 5 volts to pin 2 of the sensor and monitors the voltage across the sensor pins. The theoretical full voltage range is from 5 to 0 volts
representing maximum cold to maximum hot.
The ECM converts the monitored voltage into a digital number that relates to an engine coolant temperature. The temperature signal is then used
for a number of functions:
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Cranking enrichment.
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Warm-up enrichment.
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Acceleration enrichment.
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Air injection.
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Idle speed control.
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Enable EGR.
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Evaporative canister purge.
NOTE: Other sensor inputs are required for the initiation of most of the above listed ECM functions.
Temperature Versus Resistance And Voltage
