Scan Tool Data Definitions

WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

Aux. Coolant Pump Relay: This parameter indicates when the auxiliary engine coolant pump is on or off.
Coolant Level Switch - Range: Low/OK: This parameter indicates when the engine coolant level is low. The scan tool displays Low when the PCM detects the engine coolant level switch is open.
Displayed Coolant Temperature - Range: 32-127° C (89-260° F): This data is the coolant temperature the Instrument Cluster is attempting to display on the coolant temperature gauge. This data may differ from the monitored coolant temperature for a period of time due to filtering. The data may also differ from the monitored coolant temperature when coolant temperature is not in the range of 71-127° C (160-260° F) since the display is limited to these values. If a Class 2 communication failure occurs, this data will be at the minimum value of 32° C (89° F).
ECT - Range: -40° C to +150° C (-40° F to +302° F): The PCM applies 5.0 volts to the ECT sensor circuit. The sensor is a thermistor which changes internal resistance as the engine temperature changes. When the sensor is cold (internal resistance high), the PCM senses a high signal voltage and interprets the voltage 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.
Monitored Coolant Temperature - Range: 40-215° C (40-419° F): This data is the clusters measurement of the engine coolant temperature as provided by the PCM on the Class 2 serial data line.
SGCM Fan Speed: This parameter indicates the commanded SGCM coolant fan speed. The scan tool displays 0-100%.
SGCM Pump Status: This parameter indicates the commanded SGCM coolant pump state. The scan tool displays On and Off.
SGCM Temperature: This parameter indicates the average coolant temperature of the SGCM coolant. The scan tool displays -40° C to +150° C.