Ambient Temp Sensor: Operation

WARNING: This page is about a different car, the 2004 Chrysler Pacifica. However, it is still accessible from the selected car via links, so may be relevant.

The ambient temperature sensor is a variable resistor. A five-volt reference signal is sent to the sensor by the Front Control Module. The front control module monitors the return signal voltage on a dedicated temperature sensor signal circuit. Based upon the resistance in the sensor, the Front Control Module is programmed to correspond to a specific temperature. The Front Control Module then sends the proper ambient temperature messages over the PCI data bus circuit.

The HVAC temperature display function is supported by the ambient temperature sensor, a wiring circuit, the Front Control Module and the Programmable Communications Interface (PCI) data bus. If any portion of the ambient temperature sensor circuit fails, the Front Control Module should self-diagnose the circuit.