Head unit, component description - GF82.85-P-3140RFB

Model 205 with code 531 (COMAND APS) except code 520 (Audio 20 USB) except code 522 (Audio 20 radio) 

Model 253 with code 531 (COMAND APS) except code 520 (Audio 20 USB) except code 522 (Audio 20 radio) 

Shown on MODEL 205.0 

Location 

The head unit is located behind the instrument panel cover in the center console behind the upper control panel control unit (N72/1).

Tasks 

The head unit has the following tasks:

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

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

• Telephony
• Internet (including wireless local area network (WLAN) hotspot)
• Voice control system (VCS [SBS])
• Navigation (map navigation with data from internal hard disk) including extended functions of navigation mode
• Digital operator's manual (interactive)
• Audio (e.g. radio, CD/DVD, Bluetooth® Audio, Secure Digital (SD) card, universal serial bus (USB) including integrated Media Interface for connecting iPhones® or media transfer protocol (MTP) devices)
• Video, including TV (with CODE 865 (TV tuner))
• Emergency call (with CODE 347 (Mercedes-Benz emergency call system))

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.

Evaluating and forwarding control signals 

The head unit receives the control signals from the following components via the telematics CAN (CAN A):

• Left lower control panel (N72/4)
• Right lower control panel (N72/5)
• Upper control panel control unit
• Off-road operating panel (S70) (model 253.9 with code 430 (Off-road package))

  The head unit evaluates the data and sends function-specific CAN messages to the user interface CAN (CAN HMI). When actuating the DYNAMIC SELECT switch (N72/4s11) (as of 01.06.2015), the AGILITY SELECT switch (N72/4s1) (up to 31.05.2015), or on vehicles of model 253.9, with code 430 (Off-road package), the on/off-road menu button (S70s1), the head unit also shows selectable transmission modes 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:

• Via the telematics CAN, the head unit receives e.g. the control signals from the Audio/COMAND control panel (A40/9) and from the touchpad (A105) (up to 31.05.2015 with code 531 (COMAND APS) and as of 01.06.2015 with code 448 (Touchpad), with code 494 (USA version) or with code 498 (Japan version)). The signals from the upper control panel control unit, the left lower control panel, the right lower control panel and the off-road operating panel (model 253.9 with code 430 (Off-road package)) are also forwarded via the Audio/COMAND control panel and telematics CAN to the head unit.
• The head unit uses the telematics CAN to send e.g. control signals to the Audio/COMAND display or control signals for the displays in the upper control panel control unit to the Audio/COMAND control panel.
• The head unit uses the user interface CAN to receive e.g. from the instrument cluster (A1) the signals from the left multifunction steering wheel button group (S110) and the right multifunction steering wheel button group (S111), and from the electronic ignition lock control unit (N73), the control signals for the displays in the upper control panel control unit.
• Via the user interface CAN, the head unit sends e.g. navigation displays to the instrument cluster or the interpreted signals from the upper control panel control unit, from the left lower control panel and from the right lower control panel and from the off-road operating panel (model 253.9 with code 430 (Off-road package)) to the electronic ignition lock control unit.

Media Oriented System Transport (MOST) 

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

• Sound system amplifier control unit (N40/3) (with CODE 810 (Sound system))
• Tuner unit (A90/4) (with CODE 536 (SIRIUS satellite radio), with CODE 537 (Digital radio (DAB)) or with CODE 865 (TV tuner))

Direct line 

The head unit is equipped with the following direct connections:

• Circuit 30g
• Circuit 31
• FM 1, AM, CL [ZV] and KEYLESS-GO antenna amplifier (A2/18) (input)
• FM 2 and DAB band III antenna amplifier (A2/108) (model 205.0/1, model 253) or FM 2, DAB and TV 1 antenna amplifier (A2/131) (model 205.2, model 253) (input)
• Hands-free system microphone (A67b1) (input)
• GPS antenna (A2/23), in vehicles with CODE 348 (Emergency call/assist system) via the global positioning system antenna splitter (A2/5) (input)
• Audio muting from the emergency call system control unit (N123/4) (with CODE 348 (Emergency call/Assist system) and except CODE 810 (Sound system)) (input)
• Audio muting from the telematics services communications module (N112/1) (with code 350 (E-Call Europe emergency call system) or with code 06U (Mercedes connect me basic services) and except code 810 (Sound system)) (input)
• Low voltage differential signal (LVDS) line from the tuner unit (with CODE 865 (TV tuner)) (input)
• LVDS line from 360° camera control unit (N148) (with CODE 501 (360° camera)) (input)
• Bluetooth® antenna (A2/91) (input and output)
• WLAN antenna (A2/83)
• Multimedia connection unit (A90/5) (input and output)
• Telematics services communications module (N112/1) (with CODE B54 (Live Traffic Information)) (input and output)
• Dedicated Short-Range Communications control unit (A50/6) (with CODE 498 (Japan version), dealer option) (input and output)
• Vehicle Information and Communication System (VICS) control unit (A2/37) (with CODE 498 (Japan version), dealer option) (input and output)
• LVDS line for video data to Audio/COMAND display
• Wake-up line for MOST (output)
• Audio output (speaker) (except CODE 810 (Sound system)) (output)
• Switch-on signal and power supply for mobile phone contact plate (X237/1) (with CODE 386 (Comfort telephony)) and cellular telephone system antenna amplifier/compensator (A28/15) (with CODE 386 (Comfort telephony)) (output)
• Microphone output to emergency call system control unit (with CODE 348 (Emergency call/Assist system)) to telematics services communications module (with CODE 350 (Ecall Europe emergency call system) or with CODE 06U (Mercedes connect me basic services)) (output)
• Audio output to engine sound control unit (N40/1) (with engine 276) (output)

Ethernet 

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

Body 

The following components are integrated into the head unit:

• Arithmetic unit
• DVD changer (with CODE 814 (DVD changer)) or single DVD drive (with CODE 815 (Single DVD drive))
• Hard disk with searchable database for audio files, including cover art, cover flow and Gracenote Database
• Picture viewer
• Bluetooth® receiver
• WLAN receiver
• 3 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 494 (USA version) or CODE 460 (Canada version))
• 4-channel audio amplifier (except CODE 810 (Sound system))
• Global positioning system (GPS) receiver
• Gyro sensor and 3D acceleration sensor
• Navigation processor and traffic data recorder
• Head unit electrical fuse (A26/17f1) in the combination connector at the rear panel

Function 

• DVD drive 
• Navigation and GPS control unit 
• Gyro sensor and 3D acceleration sensor 
• Control unit for voice control system (VCS [SBS]) 

DVD drive 

With the aid of the integrated DVD drive, audio CDs/DVDs or video DVDs can be played and data (e.g. updates) from the navigation DVD can be stored on the internal hard disk.

Navigation and GPS control unit 

The navigation processor is integrated into the head unit and uses the incoming antenna signals to calculate the location of the vehicle and, after the destination has been entered, the vehicle's route.

Gyro sensor and 3D acceleration sensor 

The gyrosensor and the 3D acceleration sensor are used to determine vehicle direction changes. They are installed in the navigation processor. Calibration is not required.

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.

Cockpit Management and Data System (COMAND) control unit wiring diagram

PE82.85-P-2101-97FBA