Ambient Temp Sensor: Operation

WARNING: This page is about a different car, the 2004 Dodge Pickup and 2004 Dodge Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.

The ambient temperature sensor is a variable resistor that operates on a five-volt reference signal sent to it by the Front Control Module. The resistance in the sensor changes as temperature changes, changing the temperature sensor signal circuit voltage to the Front Control Module. Based upon the resistance in the sensor, the Front Control Module senses a specific voltage on the temperature sensor signal circuit, which it is programmed to correspond to a specific temperature. The Front Control Module then sends the proper ambient temperature messages to the EVIC, CMTC over the PCI J1850 data bus.

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

For complete circuit diagrams, refer to appropriate SYSTEM WIRING DIAGRAMS article.