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

GF54.30-P-3043CA Comfort Displays, Function
MODEL 207.3/ 4

Function requirements, general
^ Instrument cluster (A1) activated

Comfort displays in general
The comfort displays provide a fast overview of the information, which is not required to operate the vehicle.
The comfort display function encompasses the following subfunctions:
^ Function sequence for displaying outside temperature
^ Function sequence for displaying the time
^ Function sequence for scale illumination of instrument cluster

Function sequence for displaying outside temperature
The outside temperature is defined by the resistance value for the outside temperature sensor (B14). The front SAM control unit with fuse and relay module (N10/1) directly reads in the signal from the outside temperature sensor, uses it to calculate the outside temperature, and then sends this over the interior CAN (CAN B) to the instrument cluster.
The display of the outside temperature corresponds to the country coding in °C or °F in the multifunction display (A1 p13).
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 axle rpm sensor (L6/1)
- Right front axle rpm sensor (L6/2)
- Left rear axle rpm sensor (L6/3)
- Right rear axle rpm sensor (L6/4)
The Electronic Stability Program control unit (N30/4) (without code (233) DISTRONIC PLUS) or the Premium Electronic Stability program (N30/7) (with code (233) DISTRONIC PLUS) reads in the signals of the rpm sensors and transmits these via the chassis CAN (CAN E) to the instrument cluster.
The coolant temperature is recorded by the coolant temperature sensor (B11/4). The CDI control unit (N3/9) (for diesel engine) or the ME-SFI [ME] control unit (N3/10) (for gasoline engine) reads in the coolant temperature sensor signal, uses it to calculate the coolant temperature, and then sends this over the chassis CAN to the instrument cluster.
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 "engine running" or "drivetrain operational" signal set
At vehicle speeds of v < 20 km/h (for vehicle deceleration), the outside temperature display is only changed if the measured outside temperature 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.
If the vehicle speed signal is faulty, rising outside temperatures are shown every t = 10 min. in an attenuated manner.
- Coolant temperature T > 60 °C and "engine running" or "drivetrain operational" signal not set:
A delay period of max. t = 1 h prevents any apparent increase in outside temperature as a result of engine waste heat from being displayed. A rise in display value is not permitted during this delay period.
With circuit 15 OFF, the last measured outside temperature value is stored and then displayed when the circuit is reactivated. If, in the meantime, the measured outside temperature has dropped below the stored value, the currently measured temperature is displayed after t = 8 seconds.
The display range for the outside temperature lies between T = -40 and +85 °C or between T = -40 and +185 °F.
The electronic ignition lock control unit (N73) transmits the circuit status of circuit 15 via the chassis 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 displayed by the digital clock (A1p6) in the instrument cluster. For vehicles without navigation with radio (A2) (with code (510) Audio 20 incl. CD-changer or code (523) MB Audio 20 radio) or with COMAND controller unit (A40/3) (with code (528) COMAND incl. DVD changer or code (526) COMAND with single DVD drive) the time can be manually set using the left multifunction steering wheel button group (S110) and the right multifunction steering wheel button group (S111).
The signals of the multifunction steering wheel button groups are read in by the steering wheel electronics (N135) and transmitted via the steering LIN (LIN E1) to the steering column tube module control unit (N80). The steering column tube module control unit sends the signals over the chassis CAN to the instrument cluster.
For vehicles with navigation with radio with auto pilot system (A2/56) (with code (511) MB Audio 50 APS incl. DVD changer or code (525) MB Audio 50 APS radio) or with COMAND controller unit (with code (512) COMAND APS incl. DVD changer or code (527) COMAND APS with single DVD drive (with navigation)) the time is always synchronized with the installed audio components.

Additional function requirements for scale illumination of instrument cluster
^ Standing lights ON (circuit 58)
^ Circuit 15R ON

Function sequence for scale illumination of instrument cluster
The scale illumination of the instrument cluster is activated by switching on the standing light or circuit 15R.
The "Standing lights actuation active" status" is transmitted by the front SAM control unit via the interior CAN to the instrument cluster.
The electronic ignition lock control unit transmits the circuit 15R On status to the instrument cluster via the chassis CAN. The instrument cluster receives these signals and switches on the scale illumination.
The brightness is automatically adjusted by a phototransistor integrated into the instrument cluster to match the brightness level in the interior. The brightness can also be personalized by actuating the brightness control instrument illumination (A1r1).
If the instrument cluster is activated by opening the driver door, it simply switches on the multifunction display lighting. This switches off again after t = 40 s. If an active warning is displayed, this run-on time extends to t = 120 s.
If the "ambient illumination" function is activated through the "Settings" menu, "Light" in the instrument cluster, this is automatically switched on by radio frequency or infrared when the vehicle is unlocked. This causes "Standing lights actuation active" status to be set, which also activates scale illumination of the instrument cluster. If the driver door is then opened, the ambient illumination function goes off. "Standing lights actuation active" status is canceled, and the instrument cluster deactivates the scale illumination.