Scan Tool Data Definitions

Scan Tool Data Definitions

Cooling Fan Motor Command

The percent of PWM duty cycle requested from the ECM.

Cooling Fan Command

The percent of engine cooling fan commanded.

ECT

The scan tool displays -40 to +151�C (-40 to +304�F). The engine coolant temperature (ECT) sensor is mounted in the coolant stream. The powertrain control module (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, internal resistance high, the PCM monitors a high signal voltage and interprets it as a cold engine. As the sensor warms, internal resistance decreases, the voltage signal decreases and the PCM interprets the lower voltage as a warm engine.