Ambient Temp Sensor: Operation

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

The thermometer function is supported by the ambient temperature sensor, a wiring circuit, the Body Control Module (BCM), the Programmable Communications Interface (PCI) data bus, and a portion of the Compass Mini-Trip Computer module.

The ambient temperature sensor circuit can also be diagnosed by referring to AMBIENT TEMPERATURE SENSOR  and AMBIENT TEMPERATURE SENSOR CIRCUIT  under DIAGNOSIS AND TESTING. If the temperature sensor and circuit are confirmed to be OK, but the temperature display is inoperative or incorrect, refer to DIAGNOSIS AND TESTING - COMPASS MINI-TRIP COMPUTER  . For complete circuit diagrams, refer to SYSTEM WIRING DIAGRAMS .