Temperature Function

TEMPERATURE FUNCTION

The ambient temperature indicator gives an indication to the vehicle operator of the outside air temperature. This indicator is controlled by the instrument cluster microprocessor based upon cluster programming and electronic ambient temperature messages received by the cluster over the Controller Area Network (CAN) data bus from the Body Control Module (BCM) (also known as the Signal Acquisition and Actuation Module/SAM).

The ambient temperature sensor located below the front bumper is a Negative Temperature Coefficient (NTC) thermistor. The internal resistance of the sensor is reduced as the ambient temperature rises. The BCM continually monitors the resistance through the sensor to determine the temperature value to be displayed. The current value is displayed immediately after the display unit is activated. The display value will remain static regardless of decreases in the sensor resistance (temperature rising) below vehicle speeds of 10 to 15 kilometers-per-hour (6 to 9 miles-per-hour). Decreases in the sensor resistance above 15 kilometers-per-hour (9 miles-per-hour) and increases in the sensor resistance (temperature falling) regardless of vehicle speed are displayed subject to a sixty second delay.

For proper diagnosis of the ambient temperature sensor and circuits, the BCM, the ElectroMechanical Instrument Cluster (EMIC) (also known as the Cab Compartment Node/CCN or KOMBI), the CAN data bus or the electronic communication related to ambient temperature indicator operation, a diagnostic scan tool is required. Refer to the appropriate diagnostic information.