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

Model 205 up to model year 2019 with code 520 (Audio 20 USB) except code 522 (Audio 20 radio) except code 531 (COMAND® APS) 

Model 253 (except 253.99) with code 520 (Audio 20 USB) except code 522 (Audio 20 radio) except code 531 (COMAND® APS) 

Shown on model 205.0 

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 

• Control 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 

Control 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)
• Tone settings (e.g. bass, treble, fader and balance)
• Internet
• Emergency call (with code 347 (Mercedes-Benz Emergency Call System), code 350 (eCall Europe emergency call system), code 351 (HERMES emergency call system), code 360 (HERMES UMTS) or code 362 (HERMES LTE))

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

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 of 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 sends function-specific CAN signals to the relevant control units via user interface CAN (CAN HMI).

When the DYNAMIC SELECT switch (N72/4s11) (as of 01.06.2015) or the AGILITY SELECT switch (N72/4s1) (up to 31.05.2015) is operated, the head unit also shows the 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 
• 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 (A40/9) or from the touchpad (A105) (up to 31.05.2015 with code 531 (COMAND® APS), code 522 (Audio 20 radio), as of 01.06.2015 with code 448 (Touchpad), code 498 (Japan version) or code 494 (USA version)))
  • 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
• The following signals are among those transmitted by the head unit via the telematics CAN:
  • Control signals to the audio/COMAND® display
  • Control signals for displays in the upper control panel control unit to the Audio/COMAND® control panel
• The following signals are among those received by the head unit via the user interface CAN:
  • Control signals from instrument cluster (A1)
  • Control signals for the displays in the upper control panel control unit from the electronic ignition lock control unit (N73)
• The following signals are among those sent by the head unit via the user interface CAN:
  • Interpreted signals from the upper control panel control unit as well as the bottom left control panel, from the bottom right control panel and from the Off-road control panel (model 253.9 with code 430 (Off-road package))

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 205.0/3/4, model 253) or FM 2, DAB and TV 1 antenna amplifier (A2/131) (model 205.2/3/4, model 253) (input)
• Muting of the audio sources of the telematics services communications module (N112/1) (with code 350 (eCall Europe emergency call system) or with code 06U (Mercedes connect me basic services)) (input)
• Muting of audio sources from the HERMES control unit (N112/9) (with code 360 (HERMES UMTS) or code 362 (HERMES LTE), except code 810 (Sound system)) (input)
• Hands-free system microphone (A67b1) (input)
• Bluetooth® antenna (A2/91) (input and output)
• USB electrical connections (X115) (2 connections) in stowage compartment between front seats (input and output)
• USB electrical connections power supply (output)
• Low Voltage Differential Signal line (LVDS) for video data to the Audio/COMAND® display (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), as of 01.06.2016 except code 379 (Telephone module with Bluetooth® (SAP profile))) (Output)
• Microphone output to the emergency call system control unit (N123/4) (with code 348 (Emergency call/assist system)), to telematics services communication module (with code 350 (eCall Europe emergency call system) or with code 06U (Mercedes connect me basic services)) or to the HERMES control unit (with code 360 (HERMES UMTS), or code 362 (HERMES LTE)) (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 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 control unit

PE82.85-P-2101-97FBA