Comfort displays, function - GF54.30-P-3043GN

MODEL 166 as of model year 2016 

MODEL 292 

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 includes the following subfunctions:

• Function sequence for displaying outside temperature 
• Function sequence for displaying the time 
• Function sequence for instrument cluster scale illumination 

Function sequence for displaying outside temperature 

The outside temperature is detected by the outside temperature sensor (B14). The SAM control unit (N10) directly reads in the signal of the outside temperature sensor, calculates the outside temperature and sends it to the instrument cluster over the interior CAN (CAN B).

The outside temperature is displayed in °C or °F in the instrument cluster's multifunction display (A1p13) corresponding to the country coding.

The following parameters must also be taken into account to determine a correct value of outside temperature:

• Vehicle speed (falsification of value through air stream)
• Coolant temperature (falsification of value through radiant heat)

The vehicle speed is calculated on the basis of the wheel speeds.

The Electronic Stability Program control unit (N30/4) transmits information about the wheel speeds via chassis CAN 1 (CAN E1), electronic ignition lock control unit (N73) and chassis CAN 2 (CAN E2) to the instrument cluster.

The CDI control unit (N3/9) (with diesel engine) or the ME-SFI [ME] control unit (N3/10) (with gasoline engine) sends information about coolant temperature over the chassis CAN 1, electronic ignition lock control unit and chassis CAN 2 to the instrument cluster.

The coolant temperature has an influence on the outside temperature indicator as follows:

• Coolant temperature T < 60 °C:

  The current outside temperature value is always shown.

• Coolant temperature T > 60 °C and "Engine running" or "Drive train operational" signal is set:

  At vehicle speeds of v < 20 km/h (with vehicle deceleration), the outside temperature display is only changed if 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.

  The CDI control unit CDI or the ME-SFI [ME] control unit sends the "Engine running" or "Drivetrain operational" signal on vehicles except CODE ME05 (HYBRID DRIVE 80KW VARIANT (INCLUDING PLUGIN)) as follows to the instrument cluster:

• Chassis CAN 1
• Electronic ignition switch control unit
• Chassis CAN 2

The powertrain control unit (N127) sends the "Engine running" or "Drivetrain operational" signal on vehicles with CODE ME05 (HYBRID DRIVE 80KW VARIANT (INCLUDING PLUGIN)) either over the engine CAN (CAN C1) from the ME-SFI [ME] control unit or over the hybrid CAN (CAN L) from the power electronics control unit as follows to the instrument cluster:

• Chassis CAN 1
• Electronic ignition switch control unit
• Chassis CAN 2

If the vehicle speed signal is faulty, rising outside temperatures are updated every t = 10 min in an attenuated manner.

• Coolant temperature T > 60 °C and "Engine running" or "Drive train operational" signal is not set:

  A delay period of maximum t = 1 h prevents an apparent increase in outside temperature from being displayed that is caused by heat dissipated from the engine. 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 electronic ignition lock control unit sends the status of circuit 15 over chassis CAN 2 to the instrument cluster.

The display range for the outside temperature lies between T = - 40 and + 85 °C or between T = - 40 and + 185 °F.

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 by the digital clock (A1p6) in the instrument cluster. The time displayed by the instrument cluster can be entered either manually in the system settings or it is updated automatically through the received Global Positioning System (GPS) signals of the following audio equipment:

• Radio (A2) (with CODE 505 (Radio 20 NTG5 non-navigation-capable) or CODE 522 (Audio 20 radio))
• COMAND controller unit (A40/3) (with CODE 531 (COMAND APS))

The audio equipment sends the current time (time synchronization) via interior CAN to the instrument cluster.

Additional function requirements for instrument cluster scale illumination 

• Standing lights ON (circuit 58)
• Circuit 15R ON

Function sequence for instrument cluster scale illumination 

The scale illumination of the instrument cluster is activated by switching on the standing lights (circuit 58) or circuit 15R. The SAM control unit sends the status of the standing lights actuation (circuit 58) over the interior CAN to the instrument cluster.

The electronic ignition lock control unit sends the status of circuit 15 over chassis CAN 2 to the instrument cluster.

The instrument cluster receives these signals and switches on the scale illumination.

The brightness is automatically adjusted to suit the lighting conditions in the vehicle interior by a phototransistor integrated in the instrument cluster. The brightness can also be personalized by actuating the brightness control instrument illumination (A1r1).

If the instrument cluster was activated by the driver door being opened, it switches on the multifunction display's default screen. 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 using the instrument cluster, this is automatically switched on when the vehicle is unlocked by radio or infrared. This causes the "standing lights actuation active" status (circuit 58 ON) to be set, thereby also activating the scale illumination of the instrument cluster. If the driver door is then opened, the ambient illumination goes off. The "Standing lights actuation active" status (circuit 58 ON) is canceled and the instrument cluster deactivates the scale illumination.

Electrical function schematic of instrument cluster, comfort display	PE54.30-P-2056-97NBA
Overview of system components, instrument cluster (IC) component description	GF54.30-P-9996GN