Scan Tool Data Definitions

WARNING: This page is about a different car, the 2005 Chevrolet Corvette. However, it is still accessible from the selected car via links, so may be relevant.

Coolant Temperature: The scan tool displays -40 to +151° C (-40 to +304° F). This data is the coolant temperature the Instrument Cluster is attempting to display on the coolant temperature gage.
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.
Cooling Fan Speed Command: The scan tool displays %. This parameter indicates the commanded state of the cooling fan.
Coolant Level Input: The scan tool displays OK or Low. If the ground circuit opens, the scan too will display Low.