Coolant Temperature Gauge

The coolant temperature gauge gives an indication of the engine coolant temperature. The instrument cluster circuitry controls the gauge pointer position. The instrument cluster circuitry calculates the proper gauge pointer position based upon engine coolant temperature messages received from the Powertrain Control Module (PCM) on the Chrysler Collision Detection (CCD) data bus.

The PCM uses an input from the engine coolant temperature sensor and internal programming to decide what engine coolant temperature messages are required. The PCM then sends the proper messages to the instrument cluster on the CCD data bus.

If the PCM messages indicate that coolant temperature is too high, the instrument cluster circuitry moves the gauge needle to the high end of the scale on the gauge face, turns on the Check Gauges lamp, and sends a chime tone request to the Central Timer Module (CTM).

The engine coolant temperature sensor is installed in a threaded hole that penetrates a coolant passage of the engine. It is a thermistor-type sensor that changes its internal resistance with changes in engine coolant temperature.