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Head-up display, function - GF54.30-P-3048RF

Model 205, 253 with code 463 (Head-up display) 

Function requirements, general 

IMPORTANT The electronic ignition lock control unit (N73) transmits the circuit status for circuit 15 via the user interface CAN (CAN HMI) to the head-up display (A40/12).

Head-up display, general 

The head-up display projects driver-relevant information (e.g. speed, navigation information) 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. Because of the long distance between the information and the driver's eyes (approx. s = 2 m), the contents that are displayed are easy to read for the driver, with low fatigue.

IMPORTANT The head unit (A26/17) makes navigation information (for CODE 531 (COMAND APS) or CODE 357 (Map navigation) available for the head-up display. This navigation information is always displayed, regardless of whether it is also displayed on the instrument cluster. 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 this via the interior CAN (CAN B), electronic ignition lock control unit and user interface CAN to the instrument cluster. The instrument cluster activates the head-up display via the user interface CAN, processes the visual information to be displayed, and transmits this via the low voltage differential signal (LVDS) line to the head-up display.

By pressing the head-up display button once more, the head-up display will be switched off.

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 supplied with its own "warping matrix" which must be transferred to the instrument cluster.

When exchanging the instrument cluster or the head-up display, the "warping matrix" must be transferred to the new instrument cluster.

When exchanging the windshield, the head-up display must be recalibrated via the "workshop menu" in the instrument cluster or on a test stand.

Function sequence for settings 

Under the submenu "Head-up display" in the "Settings" menu in the instrument cluster, individual settings for the head-up display in terms of functional scope, brightness (relative value) and the mirror gradient (relative value) can be made.

The system is operated using the left multifunction steering wheel button group (S110) and the right multifunction steering wheel button group (S111). The steering wheel electronics system (N135) reads in the signals from the multifunction steering wheel button group buttons directly and sends them via steering LIN (LIN E1) to the steering column tube module control unit (N80). The steering column tube module control unit transmits the signals of the buttons in the multifunction steering wheel button groups via the suspension FlexRay (Flex E), electronic ignition lock control unit and user interface CAN to the instrument cluster. The instrument cluster evaluates these signals and transmits appropriate requirements via 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 the readability, both at night and also by day.

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.

IMPORTANT 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.

Function sequence for memory function (with CODE 275 (Memory package)) 

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

  Electrical function schematic for heads-up display   PE54.30-P-2065-97FBA
  Overview of system components, instrument cluster (IC) component description   GF54.30-P-9996RF 
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