GF54.30-P-3043GM Comfort Displays, Function

GF54.30-P-3043GM Comfort Displays, Function
- refinement package
- as of model year 09

General function requirements
^ Instrument cluster (A1) activated

Comfort displays in general
The convenience displays permit a rapid overview of information which is not required for operating the vehicle The comfort display function is made up of the following subfunctions:
^ Function sequence of outside temperature indicator
^ Time display function sequence
^ Instrument cluster illumination function sequence

Function sequence for outside temperature indicator
The value of the outside temperature is determined through the outside temperature indicator temperature sensor (B14), read-in by the AAC [KLA] control and operating unit (N22) (without code (581) Comfort automatic air conditioning) or from the Comfort AAC control and operating unit (N22/7) (with code (581) Comfort automatic air conditioning) and sent over the interior CAN to the instrument cluster.
In order to determine a correct outside temperature value, the following parameters must also be taken into account:
- Vehicle speed (falsification of value through airstream)
- Coolant temperature (falsification of value through radiant heat)

The vehicle speed is calculated by the instrument cluster using the signals from the left front rpm sensor (L6/1), right front rpm sensor (L6/2), left rear rpm sensor (L6/3) and the right rear rpm sensor (L6/4), which define the wheel speeds for all four wheels. The ESP control unit (N47-5) reads in the rpm sensor signals and forwards them over the engine compartment CAN to the instrument cluster.
The coolant temperature is recorded by the coolant temperature sensor (B11/4). The signals of the coolant temperature sensor are read in by the CDI control unit (N3/9) (with diesel engine) or by the ME-SFI [ME] control unit (N3/10) (with gasoline engine) and sent over the engine compartment-CAN to the instrument cluster.

The coolant temperature values exert the following influence on the outside temperature display:
- Coolant temperature T < 60 °C
The current outside temperature value is always displayed.
- Coolant temperature T > 60 °C and circuit 61 ON At vehicle speeds of v < 20 km/h the outside temperature display is only changed when the measured outside temperature value drops.
At vehicle speeds of v = 20 to 45 km/h, rising outside temperatures are displayed after a delay period of t = 8 ±2 s after t = 3 min.
At vehicle speeds of v > 45 km/h rising outside temperatures are displayed after a delay period of t = 90 s.
- Coolant temperature T > 60 °C and circuit 61 OFF
A delay period (maximum t = 1 h) prevents any apparent outside temperature increase due to engine waste heat from being displayed. A rise in display value is not permitted during this delay period.

At circuit 15 OFF the last measured outside temperature value is saved and displayed when the circuit is activated again.
The display range is between -40 °C and +85 °C or between -40 °F and +185 °F.
The display appears in the lower range of the multifunction display (A1p13).

If the instrument cluster receives implausible or no values at all from the temperature sensor for the outside temperature indicator, then the display of outside temperature is controlled, as were the coolant temperature T > 60 °C.

Function sequence of time display
The time is displayed analog in the electronic clock (A1p6).

For vehicles without code (511) Audio 50 APS incl. DVD changer or without code (525) MB Audio 50 APS radio or without code (512) COMAND APS with DVD changer or without code (527) COMAND APS with single DVD drive (with navigation) the time can only be adjusted manually using the left multifunction steering wheel button group (S110) and the right multifunction steering wheel button group (S111).
For vehicles with code (511) Audio 50 APS incl. DVD changer or code (525) MB Audio 50 APS radio or code (512) COMAND APS with DVD changer or code (527) COMAND APS with single DVD drive (with navigation) the time is synchronized automatically with the radio and navigation unit (A2/56) or the COMAND operating, display and controller unit (A40/3). Manual adjustment of the time is not possible.

Function sequence of instrument cluster illumination
The illumination is switched on automatically when the instrument cluster is activated.

If the instrument cluster is activated via the opening of the driver's door, the illumination switches off again after t = 30 s. If an active warning is displayed then the run-on time extends by a further t = 2 minutes.
The brightness is automatically adapted to the interior brightness conditions by the brightness sensor (A1b1). Depending on the light falling on the brightness sensor, the instrument cluster automatically regulates the lighting in a range between 80 % and 100 % of the maximum brightness.
The brightness can also be changed individually by pressing the instrument and switch and controls illumination button, bright (A1s4) or the instrument and switch and controls illumination button, dark (A1s5), provided that the exterior lights (ABL) are switched on.

If the rotary light switch (S1) is in the auto on/off driving lights position and if the rain/light sensor (B38/2) sends a "Darkness detected" status, the instrument cluster automatically switches to night mode.
The brightness is then approx. 50 % of the day mode and it can also be adjusted using the instrument and pushbutton unit illumination switch. If the rain/light sensor transmits the "Day" status, then the instrument cluster regulates the lighting in a range of 80 % to 100 % of the maximum brightness.
Manual readjustment via the instrument and switch and controls illumination button is not possible here.