Engine - Coolant Temperature Sensor/Switch: Description and Operation

Coolant Temperature Sensor:

PURPOSE
The PCME uses temperature sensor information in its calculations for outputs such as air/fuel ratio control, idle speed, ignition timing, and emission devices.

LOCATION
In coolant house at rear of cylinder head near crankshaft position sensor.

OPERATION
Sensor is a thermistor device whose resistance varies with changes in coolant temperature. The PCME sends a reference voltage to the sensor and measures changes in resistance as engine temperature fluctuates.

COOLANT TEMP. RESISTANCE (K OHMS)
20°C (68°F) 2.2 - 2.7
40°C (104°F) 1.0 - 1.3
60°C (140°F) 0.50 - 0.65
80°C (176°F) 0.29 - 0.35