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

Model 205

as of model year 2019

with code 506 (Audio 20 NTG 5.5 radio)

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)

Figure shows model 205.0 up to model year 2019

Fig 1: Head Unit Component Location - Model 253 With Code 531 / Except Code 520 & 522 (Shown On Model 205.0 Up To M.Y. 2019)

Courtesy of MERCEDES-BENZ USA

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 controller unit for entertainment and communication systems integrated into vehicle
Integration of smart phones
Evaluating and forwarding control signals
Reading in of input signals as well as actuation of output media and system components

Central controller unit for entertainment and communication systems integrated into vehicle

The head unit generates a structured user interface for operating the various components of the entertainment and communication system:

Audio (e.g. radio, Bluetooth® Audio, universal serial bus (USB) including integrated Media Interface for connecting iPhones® or media transfer protocol (MTP) devices)
Telephony (with address book function)
Internet
Wireless Local Area Network (WLAN)-Hotspot (with code 531 (COMAND APS))
Voice control system (SBS) (with code 506 (Radio Audio 20 NTG 5.5) only for navigation operation)
Navigation
Digital operator's manual (interactive)
Video
TV (with code 865 (TV tuner))
Emergency call (with code 351 (Emergency call system (HERMES)))

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 smart phones

The head unit enables the integration of smart phones. In order to ensure that the content is prepared in a vehicle-compatible way, only smartphone applications (apps) that have been developed for the following integration standards are supported:

Android Auto (Google)
CarPlay (Apple)

To use the smartphone applications, the smartphone must be connected to USB connector 2 (A90/5x2) (with code 531 (COMAND APS), and except code 899 (Multifunction telephony), except code 897 (Wireless mobile phone charging), except code 896 (Vehicle access and drive authorization via mobile phone)) 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
VCS
Telephony (with CarPlay)

The radio (AM and FM), vehicle settings and safety-related functions, such as the emergency call function or the breakdown assistance (with code 360 (HERMES UMTS), or with code 362 (HERMES LTE)), can still be used in any case.

With Android Auto, the following usage restrictions apply for the telephony: Calls can only be made through the connected smartphone. Telephony with code 379 (Telephone module with Bluetooth® (SAP)) is not possible.

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 operation signals (e.g. from the Audio/COMAND control panel (A40/9) (except code 446 (Touchpad only)), or from the Touchpad (A105) (with code 446 (Touchpad only)), long press of voice control system ON button (S111s4) (model 205 up to model year 2019, model 253 (except 253.99)), or the voice control ON and favorites switch (S163/2s17) (model 205 as of model year 2019, model 253.99), press of accept and terminate phone call button (S111s3) (model 205 up to model year 2019, model 253 (except 253.99)), or the accept and terminate phone call switch (S163/2s15) (model 205 as of model year 2019, model 253.99) of the right multifunction steering wheel button group (S111) (model 205 up to model year 2019, model 253 (except 253.99)), or the head unit multifunction steering wheel button group (S163/2) (model 205 as of model year 2019, model 253.99))
Forwarding of signals from the hands-free system microphone (A67b1) (model 205 up to model year 2019, model 253 (except 253.99)), or from the driver hands-free system microphone (B25/20), and from the front passenger hands-free system microphone (B25/21) (model 205 as of model year 2019, model 253.99) (e.g. for voice control or telephony)
Audio outputs (e.g. for voice control/telephony) via the speaker system or forwarding of the signals to the sound system amplifier control unit (N40/3) (with code 810 (Sound system)), or to the Midline sound system amplifier control unit (with code 853 ("Midline" sound system))
Muting radio reception in the head unit (mute function), e.g. for smartphone telephony
Forwarding of position data (e.g. global navigation system (GPS) signals, gyro sensor signals, wheel speed signals)
Forwarding of video signals generated by the smartphone to the 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.

When the smartphone is used for calling, the head unit receives and sends the telephone signals from and to the smartphone with Android Auto via the Bluetooth® antenna (A2/91), with CarPlay via the USB connection to the multimedia connection unit (except code 899 (Multifunction telephony), code 897 (Wireless mobile phone charging), code 896 (Vehicle access and drive authorization via mobile phone)).

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). Where the "Individual" drive program is selected via the DYNAMIC SELECT switch (N72/4s11) (as of 01.06.2015), or the AGILITY SELECT switch (N72/4s1) (up to 31.05.2015), or on model 253.9 with code 430 (Off-road package) via the On-road/Off-road menu button (S70s1), the head unit also shows the additional selection options in 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 following signals are among those received by the head unit via the telematics CAN:
- Operation signals from the Audio/COMAND control panel (model 205 as of model year 2019 except code 446 (Touchpad only)), or from the touchpad (with code 448 (Touchpad), or model 205 as of model year 2019, model 253.99 with code 446 (Touchpad only))
- Status signals about charge level of a mobile phone from the mobile phone cradle control unit (N123/8) (with code 897 (Wireless mobile phone charging))
- Control signals from the upper control panel control unit, from the left lower control panel, from the right lower control panel and from the Off-road control panel (model 253.9 with code 430 (Off-road package)) via the Audio/COMAND operating unit (except code 446 (Touchpad only)), or via the touchpad (with code 446 (Touchpad only))
- Initialization data from the mobile phone cradle control unit for incorporating an authorized mobile phone into the vehicle hierarchy (with code 899 (Multifunction telephony), code 897 (Wireless mobile phone charging), code 896 (Vehicle access and drive authorization via mobile phone))
- Reception of key codes from mobile phone cradle control unit for drive authorization (with code 896 (Vehicle access and drive authorization over mobile phone))
The following signals are among those transmitted by the head unit via the telematics CAN:
- 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 (with code 897 (Wireless mobile phone charging))
- Control signals for displays in the upper control panel control unit to the Audio/COMAND control panel
Model 205 up to model year 2019, model 253 (except 253.99):
Via the user interface CAN, the head unit receives, e.g. the signals of the left multifunction steering wheel button group (S110), and the right multifunction steering wheel button group (S111) as well as, from the electronic ignition lock control unit (N73), the control signals for the displays in the upper control panel control unit.
Model 205 as of model year 2019, model 253.99:
Via the user interface CAN, the head unit receives e.g. the signals of the instrument cluster multifunction steering wheel button group (S163/1), and the head unit multifunction steering wheel button group (S163/2), and from the electronic ignition lock control unit (N73) it receives the control signals for the displays in the upper control panel control unit.
The head unit transmits navigation displays to the instrument cluster, for example, or the interpreted signals from the upper control panel control unit, as well as from the left lower control panel and the right lower control panel as well as from the off-road operating panel (model 253.9 with code 430 (Off-road package)) to the electronic ignition lock control unit via the user interface CAN.

MOST

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

Midline sound system amplifier control unit (N40/2) (with code 853 ("Midline" sound system))
Sound system amplifier control unit (N40/3) (with code 810 (Sound system))
Tuner unit (A90/4) (model 205 up to model year 2019, model 253 (except 253.99) with code 536 (SIRIUS satellite radio), code 537 (Digital radio (DAB)), or code 865 (TV tuner))
TV tuner control unit (N143) (model 205 as of model year 2019, model 253.99 with code 865 (TV tuner))

Direct line

The head unit is equipped with the following direct connections:

Circuit 30g (model 205 up to model year 2019, model 253 (except 253.99))
Circuit 30t (model 205 as of model year 2019, model 253.99)
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 205.0/3), or FM 2, DAB and TV 1 antenna amplifier (A2/131) (model 205.2/4, model 253.9) (input)
Hands-free system microphone (A67b1) (input) (model 205 up to model year 2019, model 253 (except 253.99))
Driver hands-free system microphone (B25/20), and front passenger hands-free system microphone (B25/21) (input) (model 205 as of model year 2019, model 253.99)
GPS antenna (A2/23) (input)
Muting of the audio sources by the HERMES control unit (N112/9) (with code 362 (HERMES LTE), or code 360 (HERMES UMTS)) (input)
Muting of the audio sources from the emergency call system control unit (N123/4) (with code 348 (Emergency call/assist system), except code 810 (Sound system)) (input)
Muting of audio sources from the telematics services communications module (N112/1) (with code 350 (eCall Europe emergency call system), with code 06U (Mercedes connect me basic services), except code 810 (Sound system), and except code 853 ("Midline" sound system)) (input)
Low voltage differential signaling (LVDS) line from the reversing camera (B84/3) (with code 218 (Reversing camera)) (input) (model 205 up to model year 2019, model 253 (except 253.99))
LVDS line from 360° camera control unit (N148) (with code 501 (360° camera)) (input) (model 205 up to model year 2019, model 253 (except 253.99))
LVDS line for video data to the Audio/COMAND display (output) (model 205 up to model year 2019, model 253 (except 253.99))
HSVL line (high speed video link) for video data to the Audio/COMAND display (output) (model 205 as of model year 2019, model 253.99)
Bluetooth® antenna (input and output)
WLAN antenna (A2/83) (input and output)
Multimedia connection unit (input and output)
Telematics services communications module (with code B54 (Live Traffic Information)) (input and output)
Microphone output to the HERMES control unit (with code 360 (HERMES UMTS), or code 362 (HERMES LTE)) (output)
SDARS antenna (A2/105) with code 536 (SIRIUS satellite radio)
Dedicated Short-Range Communications control unit (A50/6) (with code 498 (Japan version)) (Input and output)
Vehicle Information and Communication System (VICS) control unit (A2/37) (with code 498 (Japan version), dealer option) (input and output)
Wake-up for MOST (output)
Audio output (speaker) (except code 810 (Sound system), or code 853 ("Midline" sound system)) (output)
Switch-on signal for mobile phone contact plate (X237/1) (with code 379 (Telephone module with Bluetooth® (SAP))), and cellular telephone system antenna amplifier/compensator (A28/15) (with code 379 (Telephone module with Bluetooth® (SAP profile)), or with code 899 (Multifunction telephony)) (output)
Microphone output to emergency call system control unit (with code 348 (Emergency call/assistance system), to telematics services communications module (with code 350 (eCall Europe emergency call system), or with code 06U (Mercedes connect me basic services))
Switch-on signal for mobile phone cradle control unit (with code 896 (Vehicle access and drive authorization over mobile phone), with code 897 (Wireless mobile phone charging), with code 899 (Multifunction telephony)) (output)
Wake-up-line to the telephone and stationary heater antenna changeover switch (A2/155) (with code 386 (Comfort telephony), and code B24 (Remote control for stationary heater), as of 01.06.2016)
Audio output to the engine sound control unit (N40/1) (with code B63 (Sporty engine sound)) (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.

Structure

The following components are integrated into the head unit:

Arithmetic unit
DVD drive (model 205 up to model year 2019, model 253 (except 253.99))
Hard disk with searchable database for audio files, including cover art, cover flow and Gracenote Database
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))
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 dual tuner (Digital radio) (except code 498 (Japan version), and except code 494 (USA version))
The DAB dual tuner decodes the DAB-Band-III signals in PCM signals.
4-channel audio amplifier (except code 810 (Sound system), and except code 853 ("Midline" sound system))
Global navigation system (GPS) receiver
Gyro sensor and 2Dacceleration sensor (with code 506 (Radio Audio 20 NTG 5.5)), or gyro sensor and 3Dacceleration sensor (with code 531 (COMAND APS))
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 memory (with code 355 (Pre-installation for navigation retrofit), or code 531 (COMAND APS))
Navigation processor (with code 531 (COMAND APS))
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.
Control unit for voice control system (VCS [SBS]) (with code 531 (COMAND APS))
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

	Cockpit Management and Data System (COMAND) control unit wiring diagram	Model 205 up to model year 2019 with code 531 (COMAND APS) except code 520 (Audio 20 USB) except code 522 (Audio 20 radio), Model 253 (except 253.99) with code 531 (COMAND APS) except code 520 (Audio 20 USB) except code 522 (Audio 20 radio)	PE82.85-P-2101-97FBA
	Cockpit Management and Data System (COMAND) control unit wiring diagram	Model 205 as of model year 2019 with code 506 (Audio 20 NTG 5.5 radio) except code 520 (Audio 20 USB) except code 522 (Audio 20 radio) except code 531 (COMAND APS), Model 205 as of model year 2019 with code 531 (COMAND APS) except code 506 (Audio 20 NTG 5.5 radio) except code 520 (Audio 20 USB) except code 522 (Audio 20 radio)	PE82.85-P-2110-97FBB