740 L4-2.3L SOHC VIN 88 B230F (1985)
Coolant Temperature Sensor/Switch (For Computer): Description and Operation
Coolant Temperature Sensor
Used by the fuel injection and ignition ECU:
PURPOSE
The coolant temperature sensor provides the ECUs with information regarding the engine temperature necessary for proper adjustment of injection
duration and ignition timing.
LOCATION
Located front of engine, under intake manifold.
DESIGN
The coolant temperature sensor is of the NTC (negative temperature coefficient) type. This means the higher the coolant temperature, the lower
the sensor resistance.
OPERATION
The ECU applies a regulated constant voltage to the sensor, and monitors the voltage in the circuit. As temperature increases, sensor resistance
decreases, causing a decrease in the measured voltage of the circuit.
By monitoring the circuit voltage, the ECU 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.