Additional Wiring
WARNING: This page is about a different car, the 2007 Chrysler PT Cruiser. However, it is still accessible from the selected car via links, so may be relevant.
For complete wiring diagrams, refer to SYSTEM WIRING DIAGRAMS article.
When the engine is shut off the Engine Coolant temperature is measured. While the vehicle sets with the Ignition off, the ECT is expected to drop a specific amount depending on ambient air temperature, length of shutdown time and other variables. If the temperature decrease is more than expected or less than expected, a one trip failure will occur after the first detected failure and the MIL will set after the second detected failure.