Engine - Coolant Temperature Sensor/Switch: Testing and Inspection

PURPOSE
Provides ECU with engine coolant temperature signal.

LOCATION
Top of engine near thermostat housing.

OPERATION
Sensor is a thermistor device whose resistance varies with changes in engine coolant temperature. The ECU sends a reference voltage to the sensor and measures changes in resistance as engine temperature fluctuates. The ECU uses engine temperature information in its calculations for outputs such as air/fuel ratio control and emission devices.

COOLANT TEMP. RESISTANCE (K OHMS)
-4°F (-20°C) 16.2 ± 1.6
68°F (20°C) 2.5 ± 0.2
176°F (80°C) 0.3 ± 0.1