Scan Tool Data Definitions

Scan Tool Data Definitions

ECT
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 engine control module (ECM) applies 5 volts to the ECT sensor signal circuit. The sensor is a thermistor which changes internal resistance as temperature changes. When the sensor is cold and the internal resistance is high, the ECM monitors a high signal voltage and interprets it as a cold engine. As the sensor warms and the internal resistance decreases, the voltage signal decreases and the ECM interprets the lower voltage as a warm engine.

Cooling Fan Relay Command
The cooling fan relay is commanded ON or OFF by the ECM.

FC Relay 1 Command
The cooling fan relay is commanded ON or OFF by the PCM.

FC Relay 2 Command
The cooling fan relay is commanded ON or OFF by the PCM.

Low Coolant Level
The scan tool displays YES or NO, determined by the state of the low coolant level switch.