Head Unit, Component Description - GF82.85-P-3140GW

Model 463 (except 463.342) 

as of model year 2019 

Location 

The head unit is located behind the instrument panel cover in the center console.

Tasks 

The head unit has the following tasks:

• Central operating and display unit for the entertainment and communications systems integrated into the vehicle 
• Integration of smartphones 
• Evaluating and forwarding control signals 
• Reading in of input signals as well as actuation of output media and system components 

Central operating and display unit for the entertainment and communications systems integrated into the vehicle 

The head unit provides the user with a structured and uniform user interface for the following systems:

• Audio (e.g. radio, Bluetooth® audio, universal serial bus (USB) including integrated Media Interface for connecting to iPhones® or media transfer protocol (MTP) devices)
• Telephony
• Internet
• Wireless local area network (WLAN) hotspot
• Voice control system (VCS [SBS])
• Navigation
• Digital operator's manual (interactive)
• Video
• TV (with code EM8 (TV tuner))
• Emergency call (with code EK1 (HERMES LTE communication module) or code EM2 (HERMES UMTS communication module))

The user interface is shown on the Audio/COMAND display (A40/8).

Using the "Vehicle functions" menu, equipment-dependent contents and functions of additional systems (e.g. climate control, seat adjustments) can be shown and controlled on the Audio/COMAND display.

Integration of smartphones 

The head unit enables the integration of smartphones. In order to ensure that the content is prepared in a manner suitable for the vehicle, only Smartphone apps that have been developed for the following integration standards are supported:

• Android Auto (Google)
• CarPlay (Apple)
• MirrorLink

In order to be able to use the smartphone apps, the smartphone must be connected to USB connector 2 (A90/5x2) of the multimedia connection unit (A90/5) and the integration standard selected via the "Connect" menu.

If a smartphone is connected and an integration standard Android Auto or CarPlay is activated, then the head unit is set into a special operating mode ("Integration mode"), in which the following head unit functions cannot be used:

• Media player
• Navigation (equipment dependent)
• Voice control system
• Telephony (with CarPlay)

The radio (AM and FM) functions, vehicle settings and safety-relevant functions such as, e.g. the emergency call function or breakdown assistance (with code EK1 (HERMES LTE communication module) or code EM2 (HERMES UMTS communication module)), can still be used.

With Android Auto, the following usage restrictions apply for the telephony: Calls can only be made through the connected smartphone.

If an integration standard is activated, the head unit supports the smartphone apps in the following manner:

• Volume adaptation for all audio signals
• Forwarding of control signals (e.g. from the audio/COMAND control panel (A40/9) or from the touchpad (A105), pressing and holding voice control ON and favorites switch (S163/2s17) as well as pushing the accept/terminate phone call button switch (S163/2s15) on the head unit multifunction steering wheel button group (S163/2))
• Forwarding of signals from driver hands-free system microphone (B25/20) and from front passenger hands-free system microphone (B25/21) (e.g. for voice control or telephony)
• Audio outputs (e.g. for voice control or telephony) over the speaker system or forwarding of signals to the sound system amplifier control unit (N40/3) (with code EU8 (Burmester 3D surround sound system))
• Muting radio reception in the head unit (mute function), e.g. for smartphone telephony
• Forwarding of positioning data (e.g. global navigation system (GPS) signals, signals from gyro sensor, wheel speed signals)
• Forwarding of smartphone generated video signals to audio/COMAND display
• Forwarding of status information for displaying in the instrument cluster (A1)

The smartphone applications themselves are not shown in the instrument cluster.

If the Smartphone is being used to make a call, the head unit sends the telephone signals from and to the smartphone via the Bluetooth® antenna (A2/91) with Android Auto, and with CarPlay via the USB connection to the multimedia connection unit.

Evaluating and forwarding control signals 

The head unit receives the control signals of the left lower control panel (N72/4) and the right lower control panel (N72/5) over the telematics CAN (CAN A), evaluates them and transmits function-specific CAN messages to the user interface CAN (CAN HMI). When the DYNAMIC SELECT switch (N72/4s1) is operated, the head unit also shows the selected transmission mode on the audio/COMAND display.

Reading in of input signals as well as actuation of output media and system components 

The head unit transmits and receives signals via the following connections:

• CAN 
• Media Oriented System Transport (MOST) 
• Direct line 
• Ethernet 

CAN 

The head unit is a telematics CAN and user interface CAN subscriber:

• The head unit receives the following signals via the telematics CAN, for example:
  • Control signals from audio/COMAND control panel or from the touchpad
  • Status signals about charge level of a mobile phone from the mobile phone cradle control unit (N123/8) (with code EH6 (Contactless charging system for mobile phones))
  • Control signals from the upper control panel control unit, from the left lower control panel and from the right lower control panel over the Audio/COMAND control panel
  • Initialization data from mobile phone cradle control unit for connection of an authorized mobile phone in the vehicle hierarchy (with code EH6 (Contactless charging system for mobile phones))
• The head unit transmits the following signals via telematics CAN, for example:
  • Control signals to the audio/COMAND display
  • Status signals as well as the charge level/initialization data request from mobile phone to mobile phone cradle control unit
  • Control signals for displays in the upper control panel control unit to the Audio/COMAND control panel
• The head unit receives, e.g. signals from the instrument cluster for the instrument cluster multifunction steering wheel button group (S163/1) and the head unit multifunction steering wheel button group over the user interface CAN as well as the control signals for the displays in the upper control panel control unit from the electronic ignition lock control unit (N73).
• The head unit sends, e.g. navigation displays over the user interface CAN to the instrument cluster or the interpreted signals from the upper control panel control unit as well as from the left lower control panel and from the right lower control panel to the electronic ignition lock control unit.

MOST 

The head unit exchanges data with the following control units via MOST:

• Sound system amplifier control unit (with code EU8 (Burmester 3D surround sound system))
• TV tuner control unit (N143) (with code EM8 (TV tuner))

Direct line 

The head unit is equipped with the following direct connections:

• Circuit 30t
• Circuit 31
• FM 1, AM, CL, DAB 1 antenna amplifier (A2/18) (DAB I, with code EF6 (Digital radio (DAB))) (Input)
• FM 2, DAB 2, TV 2 antenna amplifier (A2/108) (DAB II, with code EF6 (Digital radio (DAB))) (Input)
• SDARS antenna (A2/105) (with code EF7 (Sirius satellite radio)) (Input)
• Driver hands-free system microphone and front passenger hands-free system microphone (input)
• GPS antenna (A2/23) (input)
• Audio muting from HERMES control unit (N112/9) (with code EK1 (HERMES LTE communication module) or code EM2 (HERMES UMTS communication module)) (Input)
• Bluetooth® antenna (input and output)
• WLAN antenna (A2/83) (input and output)
• Multimedia connection unit (input and output)
• Dedicated Short-Range Communications control unit (A50/6) (with code Z14 (VICS (Vehicle Information + Communication System))) (input and output)
• High-speed video link (HSVL) line for video data to the Audio/COMAND display (output)
• High-Speed-Video-Link (HSVL) line for video data to instrument cluster (with code J25 (Instrument cluster - DIGITAL FULL DISPLAY)) (output)
• Wake-up for MOST (output)
• Audio output (speaker) (except code EU8 (Burmester 3D surround sound system)) (output)
• Microphone output to HERMES control unit (with code EK1 (HERMES LTE communication module) or code EM2 (HERMES UMTS communication module)) (input) (output)
• Cut-in signal for the mobile phone cradle control unit (with code EH6 (Contactless charging system for mobile phones)) (output)
• Digital instrument cluster full display fan motor (M4/12) (with code J25 (Instrument cluster - DIGITAL FULL DISPLAY))

Ethernet 

Via Ethernet, the head unit receives software uploads for all MOST subscribers from the diagnostic connector (X11/4) connected to the diagnostic unit.

Structure 

The following component parts are integrated into the head unit:

• Arithmetic unit
• Hard disk with searchable database for audio files, including cover art, cover flow and Gracenote Database
• Bluetooth® receiver
• WLAN receiver
• radio tuners for AM reception, FM phase diversity and separate FM tuner function for data services, e.g. traffic messages
• High definition (HD) radio tuner (with code ZU7 (National version for Canada) or code ZU8 (National version for the USA))
• SDAR (Satellite Digital Audio Radio Service) tuner (with code ZU7 (National version for Canada) or code ZU8 (National version for the USA))

  The SDARS tuner decodes and amplifies the satellite signals (Time For Division Multiplex (TDM)) and the terrestrial signals (Coded Orthogonal Frequency Division Multiplex (COFDM)) in PCM signals (pulse-code modulation).

• DAB twin tuner (digital radio) (except code ZJ1 (Version for Japan) and except code ZU8 (National version for the USA))

  The DAB dual tuner decodes the DAB-Band-III signals in PCM signals.

• 4-channel audio amplifier
• Global navigation system (GPS) receiver
• Gyro sensor and 3D acceleration sensor

  The gyro sensor and the 3D acceleration sensor are used to determine any change in direction of the vehicle. They are installed in the navigation processor. Calibration is not required.

• Traffic data recorder
• Navigation processor

  The navigation processor uses the incoming antenna signals to calculate the location of the vehicle and, once the destination has been entered, the vehicle's route.

• Control unit for voice control system (VCS [SBS])

  The head unit processes the voice commands, evaluates them and creates the voice output for the dialog with the user.

• Head unit electrical fuse (A26/17f1) in the combination connector at the rear panel

Wiring diagram of head unit

PE82.85-P-2110-97ZHA