Brief description of components

The SMG system comprises the following key components:

• HUD: Head-up display 

  The head-up display can be compared to a projector. The image is formed by the projection display and is illuminated by the light source.

• Display range of the head-up display 

  The display range of the head-up display is optically divided into 2 sections. The upper section is used to display navigation instructions. the lower section is used to display speed-related information.

• Windscreen 

  A special windscreen is needed for the head-up display to appear optimally.

• Button for switching head-up display on and off 

  The button is located to the right of the rotary switch for side lights and dipped headlights.

The following components are networked for the function of the head-up display (in alphabetical order):

• Active cruise control or cruise control 

  The following signals are sent by optional extra 541 "Active Cruise Control" (ACC) or optional extra 540 "Cruise Control" or optional extra 544 "Cruise Control with Brake Function":

  • Set speed (= selected driving speed)
  • Distance (ACC only)
  • Object detection (ACC only)
  • Regulation display (ACC only)
  • Transfer prompt (ACC only)
• CAS: Car access system 

  The CAS provides input signals relating to terminal status (e.g. terminal 15 ON).

  The head-up display is operational when terminal 15 is switched ON.

• CHAMP or CCC or M-ASK: Multimedia platform or Car Communication Computer or multi-audio system controller 

  To display the navigation directions in the head-up display, the following signals are sent by the CHAMP (multimedia platform: CHAMP; Central Head Unit and Multimedia Platform) or CCC or M-ASK:

  • Next road
  • Driving direction arrow
  • Distance to road intersection/junction
  • Bar gauge

  The signals are sent via the MOST (Media Oriented System Transport) data bus.

• CID and CON: Central Information Display and controller 

  The preset brightness of the head-up display can be individually set using the CID. The brightness adjustment (= difference between set value and basic setting) is stored in the head-up display through the Car and Key Memory.

  The CID can be used to select which information is displayed in the head-up display (e.g. Check-Control messages, navigation instructions).

  The controller is the control element for selecting setting in the CID.

  • E70

  The image orientation of the virtual image can be height-adjusted.

• DME or DDE: Digital engine electronics or digital diesel electronics 

  The head-up display receives signals from the DME or DDE regarding the cruise-control system or active cruise control. The signals are transmitted via the PT-CAN and K-CAN.

• FRM: Footwell module 
  • E70

  The footwell module controls and monitors the vehicle lights. Information is received and transmitted via the K-CAN data bus (body controller-area network).

  The footwell module provides the terminal 58g signal via the K-CAN. The footwell module also transmits the dimmer signal to the head-up display.

• JBE: Junction box electronics 
  • E70

  The junction box electronics is the data interface between the bus systems that are important for the head-up display:

  • Body CAN (K-CAN)
  • Powertrain CAN (PT-CAN)

  The diagnosis lead is connected to the JBE.

• KGM: Body gateway module from 09/2005 
  • E60, E61, E63, E64

  The KGM supersedes the SGM. The KGM is the data interface between the bus systems that are of importance for the head-up display:

  • Body CAN (K-CAN)
  • Powertrain CAN (PT-CAN)

  The diagnosis wire is connected to the KGM.

• KOMBI: Instrument cluster 

  The instrument cluster transmits the following signals to the head-up display through the K-CAN:

  • Vehicle road speed
  • Check-Control messages
• LM: Light module 
  • E60, E61, E63, E64

  The light module controls and monitors all vehicle lights. Information is received and transmitted via the K-CAN data bus (body controller-area network).

  The light module provides the terminal 58g signal via the K-CAN. The light module also transmits the dimmer signal to the head-up display.

• RLS: Rain-light sensor 

  Vehicles with the "head-up display" optional extra (option 610) require a special rain/light sensor.

  Modifications compared to the previous rain/light sensor:

  • Viewing angle

    On the previous rain/light sensor, the viewing angle has been directed more upwards (towards the sky). With the rain/light sensor for the head-up display, the viewing angle is directed more towards the virtual image (from the perspective of the rain/light sensor, downwards).

    The rain/light sensor measures the ambient light conditions in the background of the virtual image. Thus the display brightness is optimally adjusted to the ambient brightness of the virtual image.

  • Optical element

    The optical element is adjusted to the new viewing angle.

  • Evaluation electronics

    The evaluation electronics have also been modified (signal evaluation and software).

    As before, the signal is available via the K-CAN.

• SGM: Safety and gateway module up to 09/2005 
  • E60, E61, E63, E64

  The SGM is replaced by the KGM as from 09/2006.

  The SGM is the data interface (gateway) between the bus systems that are important for the head-up display:

  • Body CAN (K-CAN)
  • Byteflight 
  • Powertrain CAN (PT-CAN)

  The diagnosis wire is connected to the SGM.

• SZL: Steering column switch cluster 

  The steering column switch cluster (SZL) sends the signals from the Active Cruise Control (ACC) or the Cruise Control (FGR) to the head-up display.

  The settings of the ACC or FGR are selected using the steering column switch.