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

Model 205, 253 

with code 463 (Head-up display) 

Function requirements in 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 driving-related information (e. g speed, navigation instructions) via the windshield into the driver's field of view. 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. Because of the large distance between the information and the driver's eyes (approx. s = 2 m), the shown content can be read with minimum fatigue and in a comfortable manner.

IMPORTANT Model 205, 253

with code 357 (Map navigation)

with code 463 (Head-up display)

Model 205, 253

with code 463 (Head-up display)

with code 531 (COMAND APS)

The head-up display continuously projects navigation information irrespective of the display on the instrument cluster. For this purpose, the head unit (A26/17) sends corresponding data via the user interface CAN to the head-up display.

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 sends this over the high-speed video link line (HSVL) to the head-up display.

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

In model 205 as of 01.06.2018, in model 253 (except model 253.99) as of 01.06.2019 and in model 253.99, the Head-up Display can also be switched on or off per voice input.

Voice commands are received over the driver's hands-free system microphone (B25/20) and read in and evaluated directly by the head unit. The head unit sends the corresponding signals over the user interface CAN to the instrument cluster. The instrument cluster activates the Head-up Display over the user interface CAN, calculates the picture information that are to be displayed, and send this over the HSVL line to the Head-up Display.

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.

Operation is realized via the instrument cluster multifunction steering wheel button group (S163/1) (model 205 as of 01.06.2018, model 253 (except model 253.99) as of 01.06.2019 or model 253.99) or the left multifunction steering wheel button group (S110) (model 205 up to 31.05.2018 or model 253 (except model 253.99) up to 31.05.2019). The steering wheel electronics (N135) directly read in the user interventions to the multifunction steering wheel button groups and transmit these via the steering wheel CAN (CAN LR) (model 205 as of 01.06.2018, model 253 (except model 253.99) as of 01.06.2019 or model 253.99) or via the steering LIN (LIN E1) (model 205 up to 31.05.2018 or model 253 (except model 253.99) up to 31.05.2019) 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.

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 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-2065-97FBA
  Overview of system components, instrument cluster (IC) component description   GF54.30-P-9996RF 
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