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

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 includes 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 detected by the outside temperature sensor (B14). The front SAM control unit with fuse and relay module (N10/1) reads in the signal from the outside temperature sensor directly, uses this signal to calculate the outside temperature and sends the outside temperature via 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 (A1p13).

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 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 control unit (N30/7) (with CODE 233 (DISTRONIC PLUS)) reads in the signals from the RPM sensors and sends them to the instrument cluster via the chassis CAN (CAN E) up to 31.05.2013 or to the instrument cluster via chassis CAN 1 (CAN E1), the front SAM control unit and chassis CAN 2 (CAN E2) as of 01.06.2013.

The coolant temperature is recorded by the coolant temperature sensor (B11/4). The CDI control unit (N3/9) (with diesel engine) or the ME-SFI control unit (N3/10) (with gasoline engine) reads in the signal from the coolant temperature sensor, uses this signal to calculate the coolant temperature and sends the temperature to the instrument cluster via the chassis CAN up to 31.05.2013 or via chassis CAN 1, the front SAM control unit and chassis CAN 2 as of 01.06.2013.

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 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 or the ME-SFI control unit sends the "engine running" or "drivetrain operational" signal to the instrument cluster via the chassis CAN up to 31.05.2013 or to the instrument cluster via chassis CAN 1, the front SAM control unit and chassis CAN 2 as of 01.06.2013.

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

The electronic ignition lock control unit (N73) sends the status of circuit 15 via the interior 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 up to 31.05.2013 on the digital clock (A1p6) in the instrument cluster or as of 01.06.2013 on the analog clock (A70/1) in the middle of the instrument panel.

The time can either be entered manually in the system settings or is automatically updated by the received GPS data (with CODE 525 (MB Audio 50 APS radio) or CODE 511 (Audio 50 APS incl. DVD changer) or CODE 512 (COMAND APS incl. DVD changer) or CODE 527 (COMAND APS with single DVD drive (with navigation)) or CODE 531 (COMAND APS)).

The radio (A2) (with CODE 523 (MB Audio 20 radio) or CODE 510 (Audio 20 with CD changer) or CODE 505 (20 NTG5 radio without navigation capability) or CODE 522 (Audio 20 radio)) or the radio auto pilot system (A2/56) (with CODE 525 (MB Audio 50 APS radio) or CODE 511 (Audio 50 APS incl. DVD changer)) or the COMAND controller unit (A40/3) (with CODE 512 (COMAND APS incl. DVD changer) or CODE 527 (COMAND APS with single DVD drive (with navigation)) or CODE 528 (COMAND incl. DVD changer) or CODE 531 (COMAND APS)) sends information on the time via the interior CAN to the instrument cluster (time synchronization).

On vehicles as of 01.06.2013, the instrument cluster sends the request to set the analog clock via the interior CAN to the front SAM control unit. The front SAM control unit then actuates the analog clock via the instrument panel LIN (LIN 1).

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 status of circuit 15 is sent by the electronic ignition lock control unit up to 31.05.2013 via the chassis CAN to the instrument cluster or as of 01.06.2013 via chassis CAN 1, the front SAM control unit and 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. On vehicles up to 31.05.2013, the brightness can also be adjusted using the instrument illumination brightness control (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 via the "Settings", "Light" menu in the instrument cluster, it switches on automatically when the vehicle is unlocked by radio or infrared control. 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 is terminated. "Standing lights actuation active" status is canceled, and the instrument cluster deactivates the scale illumination.

	Electrical function schematic of instrument cluster, comfort display	MODEL 207.3/4 up to model year 2014	PE54.30-P-2056-97EAA
		MODEL 207.3/4 as of model year 2014	PE54.30-P-2056-97EAB
	Overview of system components, instrument cluster (IC) component description		GF54.30-P-9996CA