Fleetwood FWD V8-300 4.9L (1993)
Coolant Temperature Sensor/Switch (For Computer): Description and Operation
Coolant Temperature Sensor
Sensor Circuit
The coolant sensor is a thermistor (a resistor which varies its resistance value based on temperature) mounted in the engine coolant stream. The coolant
sensor is a two wire component which receives a reference voltage signal from the PCM/ECM to sensor pin B and a sensor reference ground from the
ECM/PCM to sensor pin A. Low coolant temperature produces a high resistance, while a high temperature produces low resistance. The PCM/ECM
supplies a voltage signal to the coolant sensor through a resistor in the PCM/ECM and measures the signal voltage output. The voltage will be high when
the engine is cold, and the voltage will be low when the engine is hot.
The sensor provides coolant temperature information to the PCM/ECM for fuel enrichment, ignition timing, canister purge control, air management, and
closed loop fuel control. A failure in the coolant sensor circuit should set either a code E014 or code E015. An intermittent problem in the coolant
sensor circuit can set a code E073.
