900 S Sedan L4-2290cc 2.3L DOHC (1994)
Coolant Temperature Sensor/Switch (For Computer): Description and Operation
Engine Coolant Temperature Sensor
PURPOSE
The engine coolant temperature sensor provides the ECM with information regarding the engine temperature necessary for proper adjustment of
injection duration.
LOCATION
On intake manifold flange, between cylinders 2 and 3.
DESIGN
The coolant temperature sensor is an NTC (negative temperature coefficient) type. This means the higher the coolant temperature, the lower the
sensor resistance.
OPERATION
The ECM applies a regulated constant voltage to the sensor, and monitors the voltage in the circuit. As temperature increases, sensor resistance
decreases, causing a increase in the measured voltage of the circuit. By monitoring the circuit voltage, the ECM can calculate the engine
temperature, and adjust the air/fuel ratio and ignition timing to meet the specific demands of the engine, at that temperature.
