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Home >> Mercedes Benz >> 2004 >> C 320 4MATIC Wagon (203.284) V6-3.2L (112.953) >> Repair and Diagnosis >> Accessories and Optional Equipment >> Navigation System >> Description and Operation >> GF82.61-P-0003PM Audio 50 APS, Function

GF82.61-P-0003PM Audio 50 APS, Function




GF82.61-P-0003PM Audio 50 APS, Function

MODEL 203.0 /2 /7 as of 24.4.04
- with CODE (525) MB Audio 50 APS radio
- up to Model Year 8







Schematic illustration up to 30.11.04
A1 Instrument cluster
A2/56 Radio and navigation unit
A2/72 Window antenna amplifier module 2
N73 EIS [EZS] control unit
N80 Steering column module
N93 Central gateway control unit
N123/1 Universal Portable CTEL Interface (UPCI [UHI]) control unit







Schematic illustration as of 1.12.04
A1 Instrument cluster
A2/56 Radio and navigation unit
A2/72 Window antenna amplifier module 2
N73 EIS [EZS] control unit
N80 Steering column module
N123/1 Universal Portable CTEL Interface (UPCI [UHI]) control unit

The radio and navigation unit (A2/56) is the central operating unit for the entertainment and communication systems integrated in the vehicle within the Media Oriented System Transport (MOST). The radio and navigation unit (A2/56) has an integrated screen to display information such as function key assignment, functions status, and operating menus.
The following functions can be operated:
- Radio drive
- Audio amplifier
- CD drive
- Telephone
- Navigation

The radio and navigation unit (A2/56) can be operated by 2 main control fields, which are located on the left and right next to the display, as well as a rotary knob and a cross-shaped rocker button.

Some functions can be activated using the left multifunction steering wheel button group (S110) and right multifunction steering wheel button group (S111) of the multifunction steering wheel. It should be noted that all button actuations on the multifunction steering wheel (MFL) are processed first by the instrument cluster (A1). The instrument cluster (A1) links the incoming button actuations with the current menu setting at the multifunction display (A1p13) and, as appropriate, transmits a corresponding CAN message via the Controller Area Network bus class B (interior) (CAN-B) to the radio and navigation unit (A2/56).

The digital components of the radio and navigation unit (A2/56), with integral audio gateway, are linked to each other by the MOST.

This bus system is used to transmit data (control commands and useful information) between the various system components. Because some of the individual components work with different data formats and require different data transfer rates, different bus systems have been installed:
- media-oriented system transport (MOST)
- Controller Area Network bus Class B (interior) (CAN-B)
- Local interconnect network (LIN) bus

The following conditions must be met for startup:
- Circuit 15R ON
- On-board power supply is 12 V
- System check carried out without faults

System activation
If the pushbutton control is pressed the radio and navigation unit (A2/56) switches on. The volume for the set audio source is regulated at the rotary switch.

The function keys switch over to the audio source desired by the user.
Settings made during navigation voice output apply as the default setting for subsequent navigation voice output. Operation of the radio and navigation unit (A2/56) via:
- Fixed programmed function keys
- Alphanumeric key block
- Eject key
- Programmable function keys
- Rotary switch with integrated hands-free button
- Cross-shaped rocker button with confirm button
- On button
- Mute button
- Display
- Control buttons on multifunction steering wheel
- Voice control system (VCS) with code (813) Voice control system (VCS [SBS])

A remote control is not planned.

Interfaces
Data is exchanged between the radio and navigation unit (A2/56) and the instrument cluster (A1) via the CAN-B.
In this way, the instrument cluster (A1) receives the audio and telephone data via the audio gateway from the radio and navigation unit (A2/56) and the current time via CAN-B for displaying in the multifunction display (A1p13).
The radio and navigation unit (A2/56) controls the following components:
- CD player with changer (in glove compartment) (A2/6), only for code (819) 6-disc CD changer
- UPCI (Universal Portable CTEL Interface) control unit (N123/1), only for code (388) Universal portable CTEL interface system
- External analog audio sources that are connected via the connection in the glove compartment

The connection in the glove compartment for an external analog audio source can be retrofitted.

Offboard diagnosis, STAR DIAGNOSIS
The radio and navigation unit (A2/56) has its own fault memory. When the fault memory is interrogated using STAR DIAGNOSIS, the data are transmitted to the radio and navigation unit (N2/56) via the MOST and can then be read out via the CAN-B by the central gateway control unit (N93) (up to 30.11.04) or from the EIS control unit (N73) (as of 1.12.04).
The audio gateway can be configured using STAR DIAGNOSIS. The following settings can be selected directly:
- Frequency bands
- Volume increase for incoming traffic messages
- Speed-dependent volume control
- Switch-off time when circuit 15 is ON





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