Scan Tool Data Definitions

Scan Tool Data Definitions
Cooling Fan Command
The percent of engine cooling fan requested from the ECM.
Desired Fan Speed
Requested fan speed from the ECM.
ECT Sensor
The scan tool displays -40°C to +151°C (-40°F to +304°F). The Engine Coolant Temperature (ECT) sensor is mounted in the coolant stream. The PCM applies 5 volts to the ECT sensor circuit. The sensor is a thermistor which changes internal resistance as temperature changes. When the sensor is cold and internal resistance is high, the PCM monitors a high signal voltage and interprets it as a cold engine. As the sensor warms and internal resistance decreases, the voltage signal decreases and the PCM interprets the lower voltage as a warm engine.
Fan Speed
Actual fan speed.