The instrument cluster determines the current outside temperature using the outside temperature sensor (NTC resistor). The outside temperature sensor is connected by a separate ground (analog ground) and a sensor line (analog positive) to the instrument cluster. The outside temperature is displayed permanently in the instrument cluster. If the outside temperature drops below +3 oC while the car is being driven, dependent on the coding, a warning tone (gong or beep for ice warning dependent on coding) is triggered and the displayed value flashes.
The display unit (oC/ oF) is determined in the coding data. However, it is possible (as of diagnosis index 31, refer to ”diagnosis program”, ”instrument cluster”, ”identification”) to change the display unit from o C to o F and from o F to o C. For this purpose the ignition lock must be switched from position ”1” (terminal ”R”) to position ”0” (terminal ”15” and terminal ”R” OFF) with the trip odometer reset button pressed. The displayed temperature unit is changed after releasing the trip odometer reset button and as of ignition lock position ”1” (terminal ”R”). The unit display selected is retained for as long as supply voltage is applied to the instrument cluster and no reset is triggered.
The display range extends from 40 oC to +50 oC. An increasing outside temperature display is damped since heat from the engine and other ambient conditions influence the outside temperature display. A drop in the outside temperature is not damped.
The instrument cluster sends the ”outside temperature” information via the body bus (K-bus). In ignition lock position ”0”, the outside temperature sensor is read by the instrument cluster at time intervals which are within the minute range. For this purpose, the instrument cluster is temporarily activated, provides the information and then switches itself off again.