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

Model 190

With Code 520 (Audio 20 USB) Except Code 531 (COMAND APS)

Shown On Model 190

Fig 1: Head Unit Components Location - Model 190 With Code 520 Except Code 531

Courtesy of MERCEDES-BENZ USA

Location

The head unit is located in the center console.

Tasks

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

Central control unit for the entertainment and communication systems integrated into the vehicle

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

Audio system (e.g. "Radio", "CD" (also MP3))
Telephony (with telephone book function)
Internet sound settings (e.g. "bass", "treble", "fader", "balance")
System settings (e.g. "Brightness" and "Contrast" of the Audio/COMAND display (A40/8))

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

Evaluating and forwarding control signals

The head unit receives the control signals from the ECO start/stop function button (S193/5) over the telematics CAN (CAN A), evaluates them and sends function-specific CAN messages over the user interface CAN (CAN HMI) to the AMG gateway control unit (N93/9).

The head unit receives the control signals from the Audio/COMAND control panel (A40/9), the touchpad (A105) (with CODE 448 (Touchpad)) and the ON/OFF button with volume control (S67) over the telematics CAN and evaluates them.

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:

Direct line

The head unit is equipped with the following direct connections:

Circuit 30 g
Circuit 31
FM 1, AM, CL [ZV] and KEYLESS-GO antenna amplifier (A2/18) (input)
FM 2 and DAB band III antenna amplifier (A2/19) (input)
Driver hands-free system microphone (B25/26) and front passenger hands-free system microphone (B25/27) (input)
Muting of audio sources from the telematics services communications module (N112/1) (with code 350 (eCall Europe emergency call system)) (input)
Muting of audio sources from the HERMES control unit (N112/9) (with code 360 (HERMES UMTS)) (input)
Bluetooth® antenna (A2/91) (input and output)
USB electrical connections (X115) (2 connections) in stowage compartment under armrest between the front seats (input and output)
Audio output (speaker) (output)
Microphone output to telematics services communications module (with CODE 350 (eCall Europe emergency call system)) (output)
Microphone output to the HERMES control unit (with code 360 (HERMES UMTS)) (output)
Switch-on signal (wake-up signal) for mobile phone contact plate (X237/1) (with CODE 386 (Comfort telephony)) (output)

Direct line

CAN

The head unit is a telematics CAN and user interface CAN subscriber:
The head unit, e.g. receives control signals from the Audio/COMAND control panel or from the touchpad over the telematics CAN (with CODE 448 (Touchpad)).
The head unit sends, e.g. control signals to the Audio/COMAND display over the telematics CAN.
The head unit receives, e.g. from the instrument cluster (A1), the signals of the left multifunction steering wheel button group (S110) and the right multifunction steering wheel button group (S111) via the user interface.
The head unit sends, e.g. the interpreted signals from the ECO start/stop function button over the user interface CAN to the AMG gateway control unit.

Body

The following components are integrated in the head unit:

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