Riviera V6-3.8L VIN K (1996)
Coolant Temperature Sensor/Switch (For Computer): Description and Operation
Engine Coolant Temperature (ECT) Sensor
PURPOSE
The Engine Coolant Temperature (ECT) sensor is a thermistor (a resistor which changes value based on temperature) mounted in the engine
coolant stream. Low coolant temperature produces a high resistance (100,000 ohms at -40°C (-40°F) while high temperature causes low resistance
(70 ohms at 130°C (266°F).
OPERATION
The PCM supplies a 5 volt signal to the engine coolant temperature sensor through a resistor in the PCM and measures the voltage. The voltage
will be high when the engine is cold, and low when the engine is hot. By measuring the voltage, the PCM calculates the engine coolant
temperature. The scan tool displays engine coolant temperature in degrees. After engine startup, the temperature should rise steadily to about 90°C
(194°F) then stabilize when thermostat opens. If the engine has not been run for several hours (overnight), the engine coolant temperature and
intake air temperature displays should be close to each other.
Engine coolant temperature affects most systems the PCM controls. A hard fault in the engine coolant sensor circuit should set DTC P0117 or
DTC P0118; an intermittent fault should set a DTC P1114 or P1115.
