Circuit/System Description

WARNING: This page is about a different variant/trim than selected.

The engine coolant temperature (ECT) sensor is a variable resistor that measures the temperature of the engine coolant. The engine control module (ECM) supplies 5 V to the ECT sensor signal circuit and a ground for the low reference circuit.

The purpose of this diagnostic is to analyze the performance of the thermostat by comparing the measured ECT to a modeled ECT using information from the following inputs:

ECT
Engine load
Intake air temperature (IAT)
Mass air flow (MAF)
Vehicle speed (VS)

The ECM uses the start-up ECT and ambient air temperature to begin the diagnostic calculation. This diagnostic monitors the amount of energy going into and out of the engine cooling system during the warm up process to determine if the ECT does increase normally and then maintains that temperature within a calibrated range of the modeled ECT.