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

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

General function requirements
^ Instrument cluster (A1) activated

Comfort displays in general
The comfort displays function permits a rapid overview of the information which however is not required for operating the vehicle. The comfort display function is made up of the following subfunctions:
^ Function sequence for displaying outside temperature
^ Function sequence for displaying the time
^ Night View Assist display function sequence (with code (610) Night View Assist)
^ Instrument cluster illumination function sequence

Function sequence for displaying outside temperature
The outside temperature value is defined through the resistance value of the outside temperature indicator temperature sensor (B14). The front SAM control unit with fuse and relay module (N10/1) reads in the resistance value of the outside temperature indicator temperature sensor directly, calculates from this the outside temperature T in °C and transmits a corresponding signal to the instrument cluster via the interior CAN (CAN B), central gateway control unit (N93) and central CAN (CAN F). The instrument cluster receives the signal and actuates the outside temperature indicator (A1p4) accordingly.
The outside temperature is displayed according to the country coding in either °C or °F.

The following parameters must also be taken into account to determine a correct value of outside temperature:
- Vehicle speed (falsification of value through airstream)
- Coolant temperature (falsification of value through radiant heat)

The vehicle speed is calculated on the basis of the wheel speeds. The wheel speeds are recorded by the following components:
- Left front rpm sensor (L6/1)
- Right front rpm sensor (L6/2)
- Left rear rpm sensor (L6/3)
- Right rear rpm sensor (L6/4)

The regenerative braking system control unit (N30/6) reads in the signals from the rpm sensors and transmits these to the instrument cluster via the chassis CAN (CAN E), central gateway control unit and central CAN.

The instrument cluster receives the signals from the rpm sensors and calculates the current vehicle speed.

The coolant temperature is recorded by the coolant temperature sensor (B11/4). N3/10e ME-SFI control unit reads in the signal from the coolant temperature sensor and transmits the corresponding value on the chassis CAN. The central gateway control unit passes this on to the instrument cluster via the central CAN.

The coolant temperature values have an influence on the outside temperature indicator as follows:
- 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 (12 mph) the display of outside temperature is only changed when the measured outside temperature value drops.

At vehicle speeds of v = 20 and 45 km/h, rising outside temperatures are displayed after a delay period of 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 = 2 h) prevents an apparently increased outside temperature being displayed due to engine waste heat. A rise in display value is not permitted during this delay period.

With circuit 15 Off, the last measured coolant temperature value is stored and displayed when reactivated. 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).

The EIS (EZS) control unit (N73) transmits the status of circuit 15 to the instrument cluster via the chassis CAN, central gateway control unit and central CAN. If the instrument cluster receives implausible values or no values at all for coolant temperature, the display of outside temperature is controlled as if the coolant temperature were T > 60 °C.

Function sequence for displaying the time
The time is shown on the analog clock (A70/1).
The time is adjusted via the COMAND control unit (A40/3). When adjusting, the instrument cluster reads in the signals directly via the central CAN.
For vehicles with code (527) COMAND APS with single DVD drive (with navigation) or code (529) HIGH Class Japan or code (530) COMAND APS USA (with navigation) the time synchronizes itself automatically via the Global Positioning System (GPS) signal received by the COMAND control unit.
Manual adjustment of the time is only possible here if automatic synchronization is switched off on the instrument cluster.

After updating the time stored in the instrument cluster, the instrument cluster transmits a corresponding signal via the central CAN, central gateway control unit and interior CAN to the upper control panel control unit (N72/1).
The upper control panel control unit actuates the analog clock via the instrument panel LIN (LIN 1).

Additional function requirements, Night View Assist display (with code (610) Night View Assist)
^ Night View Assist active

Night View Assist display function sequence (with code (610) Night View Assist)
By pressing the Night View Assist button (S1s9) the display of Night View Assist camera (B84/2) pictures on the multifunction display is requested.

The upper control panel control unit reads in the status of the Night View Assist button via the instrument panel LIN and transmits this to the instrument cluster via the interior CAN, central gateway control unit and central CAN and to the Night View Assist control unit (N101) via the chassis CAN.
The instrument cluster replaces the standard display of the electronic speedometer (A1p8) with the bar graph display with video image.
The Night View Assist control unit transmits the video images from the Night View Assist camera via the low voltage differential signal (LVDS) line to the instrument cluster.
The pictures from the Night View Assist camera are now shown in the multifunction display. Extremely bright image areas that blind the driver are suppressed. Consequently it is made possible for the driver to be aware of other picture contents (e.g. obstacles, pedestrians or cyclists).
The brightness distribution is processed in the night view assist control unit.

Instrument cluster illumination function sequence
The background illumination of the multifunction display and the scale illumination of the instrument cluster is activated in the case of the following events:
- Unlocking the vehicle with the transmitter key (A8/1)
- Open or close driver door
- Change of status "Transmitter key inserted"
- Switching on the standing lights
- Activation of circuit 15R
- Operation of OK button (S110s6)
- Operation of "Back" and VCS Off button (S110s4)
- Operation of electric parking brake switch (S76/15)

If the scale illumination of the instrument cluster has been activated and no further action takes place, the instrument cluster switches off the scale illumination after a time interval of t = 30 s has passed. If a fault message is displayed, this time interval extends to t = 120 s.

The EIS [EZS] control unit transmits the central locking status and the circuit status of circuit 15R to the instrument cluster via the chassis CAN, central gateway control unit and central CAN.
The left front door control unit transmits the status of the driver door N69/1 to the instrument cluster via the interior CAN, central gateway control unit and central CAN.
The front SAM control unit transmits the status of the standing light actuation to the instrument cluster via the interior CAN, central gateway control unit and central CAN.
The steering column tube module transmits the status of the left multifunction steering wheel button group (S110) to the instrument cluster (N80) via the steering LIN (LIN E1), chassis CAN, central gateway control unit and central CAN.
The electric parking brake control unit (A13) transmits the electric parking brake switch status via the front end CAN (CAN G), central gateway control unit and central CAN to the instrument cluster.

The instrument cluster illumination is automatically adapted to the brightness conditions of the interior corresponding to the signals from the right brightness sensor (A1b2) and left brightness sensor (A1b3).
Depending on the light incidence the instrument cluster regulates the illumination between P = 80 and 100 % of the maximum brightness.
When the rain/light sensor (B38/2) transmits the status "Darkness recognized" the instrument cluster switches over to night mode automatically. The brightness is then approx. 50 % of day mode. As soon as the rain/light sensor transmits the "Day" status, the instrument cluster regulates the lighting again to between P = 80 % and 100 % of the maximum brightness.

The overhead control panel control unit (N70) reads in the rain/ light sensor signal and sends this via the interior CAN, central gateway control unit and central CAN to the instrument cluster.
The instrument illumination brightness can also be changed individually by using the switch and controls illumination/Night View Assist display brightness control (S6/2r1), provided that the exterior lighting is turned on.