Ambient Temp Sensor: Operation

WARNING: This page is about a different car, the 2005 Dodge Grand Caravan, 2005 Dodge Caravan, and 2005 Chrysler Town & Country. 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 by the Powertrain Control Module (PCM). The resistance in the sensor changes as temperature changes, changing the temperature sensor signal circuit voltage to the PCM. Based upon the resistance in the sensor, the PCM senses a specific voltage on the temperature sensor signal circuit, which it is programmed to correspond to a specific temperature. The PCM then sends the proper ambient temperature messages to the Electronic Vehicle Information Center (EVIC)/Compass Mini-Trip Computer (CMTC) over the Programmable Communication Interface (PCI) data bus.

The thermometer function is supported by the ambient temperature sensor, a wiring circuit, the PCM, the PCI data bus, and the Electronics module. If any portion of the ambient temperature sensor circuit fails, the PCM will self-diagnose the circuit.

The ambient temperature sensor circuit can also be diagnosed manually (Refer to ELECTRICAL/OVERHEAD CONSOLE/AMBIENT TEMP SENSOR - DIAGNOSIS AND TESTING - AMBIENT TEMPERATURE SENSOR CIRCUIT) . If the temperature sensor and circuit are confirmed to be OK, but the temperature display is inoperative or incorrect, (Refer to ELECTRICAL/OVERHEAD CONSOLE - DIAGNOSIS AND TESTING) to determine the cause. For complete circuit diagrams, refer to appropriate SYSTEM WIRING DIAGRAMS article.