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

Model 213 up to model year 2021

with code 520 (Audio 20 USB)

except code 506 (Audio 20 NTG 5.5 radio)

except code 522 (Audio 20 radio)

except code 531 (COMMAND APS)

Shown on model 213.0

Fig 1: Head Unit Components Location - Model 213 Up To Model Year 2021 With Code 520

Courtesy of MERCEDES-BENZ USA

Location

The head unit is centrally located in the instrument panel behind the panel at the level of the upper control panel control unit (N72/1).

Tasks

Central controller unit for entertainment and communication systems integrated into vehicle
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 system (e.g. "Radio")
Telephony (with address book function)
Internet
- sound settings (e.g. "bass", "treble", "fader", "balance")
System settings (e.g. "Brightness" and "Contrast" of the Audio/COMMAND display (A40/8))
Emergency call (with code 351 (Emergency call system (HERMES)))

The user interface is shown on the Audio/COMMAND display.

Evaluating and forwarding control signals

The head unit receives the operation 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/COMMAND 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
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/COMMAND control panel (A40/9) (except code 446 (Touchpad only)) or from the touchpad (A105) (with code 448 (Touchpad) or code 446 (Touchpad only))
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/COMMAND control panel
The following signals are among those transmitted by the head unit via the telematics CAN:
Control signals to the audio/COMMAND display
Control signals for displays in the upper control panel control unit to the Audio/COMMAND control panel
Via the user interface CAN, the head unit receives e.g from the instrument cluster (A1) 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 uses the user interface CAN to send, e.g. the interpreted signals from the left lower control panel, the right lower control panel and the non-evaluated signals from the upper control panel control unit to the electronic ignition lock control unit.

Direct line

The head unit is equipped with the following direct connections:

Circuit 30t
Circuit 31
FM 1, AM, CL [ZV], DAB and KEYLESS-GO antenna amplifier (A2/18) (input)
FM 2 and DAB Band III antenna amplifier (A2/108) (model 213.0) or FM 2, DAB and TV 2 antenna amplifier (A2/19) (model 213.2) (input)
Driver hands-free system microphone (B25/20) and front passenger hands-free system microphone (B25/21) (input)
Audio muting from the HERMES control unit (N112/9) (with code 360 (HERMES UMTS)) (input)
High Speed Video Link (HSVL) line from parking system control unit (N62) (with code 235 (Parking Pilot with PARKTRONIC), with code P44 (Parking Package)) or from reversing camera control unit (N66/2) (with code 218 (Reversing camera) and except code 235 (Parking Pilot with PARKTRONIC) and except code P44 (Parking Package)) (input)
Bluetooth® antenna (A2/91) (input and output)
Multimedia connection unit (A90/5) (2 connections) in stowage compartment between the front seats (input and output)
HSVL line for video data to Audio/COMMAND display (output)
Audio output (speaker) (output)
Switch-on signal and power supply for the mobile phone contact plate (X237/1) (with code 379 (Telephone module with Bluetooth® (SAP))) or the cellular telephone system antenna amplifier/compensator (A28/15) (with code 379 (Telephone module with Bluetooth® (SAP)) up to 31.05.2016) (output)
Microphone output to the HERMES control unit (with code 360 (HERMES UMTS)) (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 in the head unit:

Central computer
Searchable database for audio files, including cover art and cover flow
3 radio tuners for AM reception, FM phase diversity and separate FM tuner function for data services, e.g. traffic messages
4-channel audio amplifier
Head unit electrical fuse (A26/17f1) in the combination connector at the rear panel

Wiring diagram of head unit

PE82.85-P-2110-97DBB