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Home >> Mercedes Benz >> 2021 >> S560 4Matic >> Repair and Diagnosis >> Electrical >> Motors, Switches, Relays >> Electrical System, Equipment & Instruments - 217 Chassis (2 Of 8) >> Basic Knowledge >> Head-Up Display, Function - GF54.30-P-3048LF

Head-Up Display, Function - GF54.30-P-3048LF

Model 217, 222 

with code 463 (Head-up display) 

Function requirements in general 

Head-up display, general 

The head-up display projects driver-relevant information (e.g. speed, navigation information etc.) onto the windshield and into the field of view of the driver. Only information that is redundant to the instrument cluster (A1) is shown.

The viewer sees the display floating just above the engine hood of the vehicle at the level of front edge of the engine hood. The driver's head must be in a clearly defined area ("head motion box") for this. The position of the "head motion box" can be vertically adjusted for different driver sizes using an adjusting mechanism inside the head-up display components. Due to the long distance between the information and the driver's eye (approx. s = 2 meters), the contents that are displayed are easy to read for the driver, with low fatigue.

The head unit (A26/17) (as of 01.06.2017 (model 222) or 01.12.2017 (model 217)) or the COMAND controller unit (A40/3) (up to 31.05.2017 (model 222) or 30.11.2017 (model 217)) provides navigation information for the Head-up Display. This navigation information must be sent independently of potential display on the instrument cluster. The head unit (as of 01.06.2017 (model 222) or 01.12.2017 (model 217)) or the COMAND controller unit (up to 31.05.2017 (model 222) or 30.11.2017 (model 217)) transmits navigation information to the Head-up Display via the user interface CAN.

The head-up display function includes the following subfunctions:

Function sequence: switching ON/OFF 

By pressing the head-up display button (S6/1s6) in the driver side instrument panel button group (S6/1), the head-up display can be switched on or off. The front SAM control unit (N10/6) reads in the status of the head-up display button via the instrument panel LIN (LIN 1) and transmits the request for switching on/off to the head-up display and instrument cluster via the interior CAN (CAN B), electronic ignition lock control unit and user interface CAN. The instrument cluster calculates the image information that should be shown in the Head-up Display and sends this over the HSVL (High-Speed-Video-Link) line to the Head-up Display.

IMPORTANT To compensate for dimensional tolerances, the instrument cluster contains a so-called "warping engine" (visual processing) in order to artificially equalize visual information in advance. This ensures that an equalized, straight image appears in the driver's field of vision. The head-up display is delivered with its own "Warping Matrix", which must be transmitted to the instrument cluster. When exchanging the instrument cluster or head-up display, the "warping matrix" must be updated in the new instrument cluster. When exchanging the windshield, the head-up display must be recalibrated via the "workshop menu" in the instrument cluster or via a test stand.

Function sequence for settings 

In the instrument cluster, the "Head up display" submenu can be used to make individual settings for the head-up display with regard to position (relative value), brightness (relative value) and display contents.

Operation occurs via the instrument cluster finger navigation pad (S163/1s10) in the instrument cluster multifunction steering wheel button group (S163/1) (as of 01.06.2017 (model 222) or 01.12.2017 (model 217)) or the OK button n/(S110s6) in the left multifunction steering wheel button group (S110) (up to 31.05.2017 (model 222) or 30.11.2017 (model 217)). The steering wheel electronics (N135) directly reads in user interventions on the multifunction steering wheel button group and transmits these to the steering column tube module control unit (N80) via the steering wheel CAN (CAN LR) (as of 01.06.2017 (model 222) or 01.12.2017 (model 217)) or via the steering LIN (LIN E1) (up to 31.05.2017 (model 222) or 30.11.2017 (model 217)). The steering column tube module control unit sends the signals to the instrument cluster over the suspension FlexRay (Flex E), electronic ignition lock control unit and the user interface CAN. The instrument cluster sends corresponding requests over the user interface CAN to the Head-up Display.

Function sequence for automatic brightness control 

The brightness of the head-up display is adjusted automatically to the ambient brightness. This guarantees readability both during the day and at night. In case of an unfavorable position of the sun (sun low on the horizon directly in front of the vehicle) it may cause the display to be unreadable. In case of wet road surfaces, the background of the head-up display can become so bright that the display is barely visible.

The head-up display light sensor (B38/2b4) in the rain/light sensor with additional functions (B38/2) determines the current road surface brightness. The rain/light sensor with additional functions reads in the signals of the head-up display directly and transmits these via the rain/light sensor LIN (LIN B16), front SAM control unit, interior CAN, electronic ignition lock control unit and user interface CAN to the head-up display. Based on these data, the head-up display adjusts its brightness dynamically to the respective conditions.

Function sequence for memory function (model 222 with code 275 (Memory Package), model 217) 

The position of the "head motion box" can be saved and called up together with the driver's seat position. The request to save or take the memory position is transmitted by the driver seat control unit (N32/1) via the interior CAN, electronic ignition lock control unit and user interface CAN to the head-up display.

  Electrical function schematic for Head-up Display   PE54.30-P-2065-97SEA
  Overview of system components, instrument cluster (IC) component description Model 217, 222
up to model year 2018
with code 463 (Head-up display)		 GF54.30-P-9996LF 
    Model 217, 222
as of model year 2018
with code 463 (Head-up display)		 GF54.30-P-9996LFM 
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