Normal Operation
WARNING: This page is about a different car, the 2006 Mercury Grand Marquis and 2006 Ford Crown Victoria. However, it is still accessible from the selected car via links, so may be relevant.
The powertrain control module (PCM) receives the engine coolant temperature status through hardwired circuitry to the cylinder head temperature sensor. The instrument cluster receives the engine coolant temperature data from the PCM over the controller area network (CAN). The instrument cluster monitors the engine coolant temperature data received from the PCM and when the engine coolant temperature is high, the coolant over temperature warning indicator illuminates.