External Temperature Display
The ambient air temperature sensor is monitored by the PCM. The PCM sends the raw value through the High Speed Controller Area Network (HS-CAN) to the Body Control Module (BCM), and from the BCM through the Medium Speed Controller Area Network (MS-CAN) to the HVAC module. The HVAC module filters and stabilizes the value and sends it to the FDIM to display the temperature, through the MS-CAN .
While the actual external temperature can vary continuously, the value that is displayed updates at a specific rate depending on whether or not the engine is "hot" and whether or not the vehicle is moving.
When the external temperature is rising, the display updates slowly.
Updates (when the actual external temperature is higher than currently displayed value) is limited to 0.6°C (1°F) every 20 seconds while the vehicle is moving at greater than 24 km/h (15 mph) for more than 90 seconds or 0.6°C (1°F) every 20 minutes if the vehicle is not moving at this speed. This is to prevent the heat from the engine compartment from affecting the accuracy of the display.
When the external temperature is dropping, the display updates quickly.
Updates (when the actual external temperature is lower than currently displayed value) are limited to 0.6°C (1°F) every 2 seconds (regardless of vehicle speed). Consequently the display essentially follows the drop experienced by the external temperature thermistor.
The ambient air temperature sensor is monitored by the PCM. The PCM sends the raw value through the High Speed Controller Area Network (HS-CAN) to the Body Control Module (BCM), and from the BCM through the Medium Speed Controller Area Network (MS-CAN) to the HVAC module. The HVAC module filters and stabilizes the value and sends it to the FDIM to display the temperature, through the MS-CAN .
While the actual external temperature can vary continuously, the value that is displayed updates at a specific rate depending on whether or not the engine is "hot" and whether or not the vehicle is moving.
When the external temperature is rising, the display updates slowly.
Updates (when the actual external temperature is higher than currently displayed value) is limited to 0.6°C (1°F) every 20 seconds while the vehicle is moving at greater than 24 km/h (15 mph) for more than 90 seconds or 0.6°C (1°F) every 20 minutes if the vehicle is not moving at this speed. This is to prevent the heat from the engine compartment from affecting the accuracy of the display.
When the external temperature is dropping, the display updates quickly.
Updates (when the actual external temperature is lower than currently displayed value) are limited to 0.6°C (1°F) every 2 seconds (regardless of vehicle speed). Consequently the display essentially follows the drop experienced by the external temperature thermistor.
