LEMON Manuals: Even more car manuals for everyone
Home >> Mercedes Benz >> 2012 >> GLK350 Base >> Repair and Diagnosis >> Electrical >> Gauges >> Electrical System, Equipment & Instructions - 204 Chassis - 1 Of 3 >> Basic Knowledge >> Comfort Displays, Function - GF54.30-P-3043CE

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

MODEL 204.0/2 as of model year 2009 

MODEL 204.3 

MODEL 204.9 

Function requirements, general 

Comfort displays in general 

The comfort displays function provides a quick overview of supplementary information that is not required for operation of the vehicle. The comfort display function includes the following subfunctions:

Function sequence for displaying outside temperature 

The outside temperature is defined by the resistance value of 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 outside temperature is displayed according to the country coding in either °C or °F. In order to determine the correct outside temperature value, the following parameters must also be taken into account:

The Electronic Stability Program control unit (N30/4) reads in the signals from the left front axle rpm sensor (L6/1), right front axle rpm sensor (L6/2), left rear axle rpm sensor (L6/3) and right rear axle rpm sensor (L6/4) directly and sends them via the chassis CAN (CAN E) to the instrument cluster. 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). 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 directly, uses the signal to calculate the coolant temperature and sends the temperature via 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 shown.

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

At vehicle speeds of v < 20 km/h (12 mph) (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.

IMPORTANT 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 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 -40 °C and +85 °C or between -40 °F and +185 °F

IMPORTANT The circuit 15 status is sent by the electronic ignition lock control unit (N73) over the interior CAN to the instrument cluster.

The outside temperature is shown on the following displays on the instrument cluster:

Function sequence for displaying the time 

The time is shown digitally on the following displays on the instrument cluster:

On vehicles with radio (A2) (with code (510) Audio 20 with CD changer or code (523) MB Audio 20 radio) or with COMAND controller unit (A40/3) (with code (528) COMAND incl. DVD changer), the time can only be set manually 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 routes the signals over the chassis CAN to the instrument cluster.

On vehicles with radio with autopilot system (A2/56) (with code (511) 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 synchronized with the installed audio components by means of the received Global Positioning System (GPS) signal.

IMPORTANT On vehicles with code (460) Canada version, with code (494) USA version or with code (498) Japan version the time can also be set using the multifunction steering wheel button groups.

Function sequence for illumination of instrument cluster 

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, the run-on time is extended by a further t = 2 min. The brightness is automatically adapted to the light conditions in the interior compartment by means of 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 adjusted by turning the instrument illumination brightness control (A1r1) (model 204.9 up to 31.5.13 with code (442) Comfort multifunction steering wheel, model 204.9 without code (442) Comfort multifunction steering wheel, model 204.0/2/3), provided that the exterior lights are switched on.

IMPORTANT If the light sensor (B38/1) (without code (345) Rain sensor) or the rain/light sensor (B38/2) (with code (345) Rain sensor) detects "darkness", 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 illumination brightness control.

Additional function requirements for output of a gearshift recommendation 

Function sequence for output of a gearshift recommendation 

A gearshift recommendation is displayed when the engine rpm and the engine load reach a predefined level. The display consists of an arrow indicating a recommended upshift or downshift plus the number of the recommended gear (e.g. "↑3").

The gear recommendation output is shown on the following displays on the instrument cluster:

To this end, the CDI control unit or the ME-SFI [ME] control unit evaluates the load and speed information and compares it against the current vehicle speed. The vehicle speed signal is sent to the ME-SFI [ME] control unit or CDI control unit from the instrument cluster over the chassis CAN. The request to display the gearshift recommendation is sent from the ME-SFI [ME] control unit or CDI control unit over the chassis CAN to the instrument cluster.

  Electrical function schematic of instrument cluster, comfort display   PE54.30-P-2056-97FAB
  Overview of system components, instrument cluster (IC) component description   GF54.30-P-9996CE 
scientia non olet · About LEMON Manuals