Engine Coolant Temperature Gauge
WARNING: This page is about a different car, the 2005 Mercury Mountaineer and 2005 Ford Explorer. However, it is still accessible from the selected car via links, so may be relevant.
The PCM receives the engine coolant temperature status through hardwired circuitry to the engine coolant temperature (ECT) sensor. The instrument cluster receives the engine coolant temperature data from the PCM through the CAN circuits. The instrument cluster monitors the engine coolant temperature data received from the PCM and commands the temperature gauge indication with a corresponding movement of the pointer. If the instrument cluster receives no signal the temperature gauge defaults to the cold position.