1997 MERCEDES-BENZ ML320 radio code

Fig. 5: Identifying Digital Data Bus (D2B), Function
Digital Data Bus (D2B)
The Digital Data Bus (D2B) is a data transmission system for the communication and information components,
which utilizes the optical data transfer options. Data transfer is conducted by means of optical pulses, which are
transferred over fiber optical cables to the connected communication and information components. Audio and
command signals are converted in the source components into optical pulses and transmitted via fiber optical
cables. The optical signal is converted back to an electronic signal in the target component. Because of the high
transfer rate, the Digital Data Bus (D2B) can transfer audio and command signals simultaneously. Simultaneous
transfer of source data and command data over the Digital Data Bus (D2B) significantly reduces the amount of
cabling. The connected components require 2 lines for the voltage supply (electrical) and 2 lines (input/output)
for the fiber optical cable of the Digital Data Bus (D2B) and one line for the wake-up signal (electrical).
In addition to this the fiber optical cable can transfer several pieces of source data simultaneously (e.g. music
and voice from 2 components), without compromising the data content.
Functional sequence on example of "Play CD" on model 220
Pressing "Play" on the radio (A2) sends a command signal over the Digital Data Bus (D2B) to the CD player
with changer (in trunk) (A2/6), for vehicles with code (819) 6-disc CD changer. The audio signals from the CD
player with changer (in the trunk) (A2/6), for vehicles with code (819) 6-disc CD changer, are then sent over the
Digital Data Bus(D2B) as source data to the Sound amplifier (A2/13), or for vehicles with code (810) to the
sound system. The target components, the Sound amplifier (A2/13), or for vehicles with code (810) the sound
system, the source data are then converted back to electrical signals and reproduced as sound.
Data transfer using fiber optic cables has the following advantages:
Extremely high data transmission rate
Prevents tapping and cross talk
Insensitive to electromagnetic radiation

2001 Mercedes-Benz ML320
1998-2005 ACCESSORIES & BODY, CAB Electrical System - Body - 163 Chassis
me
Saturday, October 02, 2010 3:30:04 PMPage 10 © 2006 Mitchell Repair Information Company, LLC.

Short-circuit resistance
Zero potential connection of components
No oxidation
Low weight of fiber optical cable
Minimum diameter of wiring harness
The digital data bus (D2B) has a closed ring structure. The communication and data components are arranged
here in a distributor line (in-series circuit). This arrangement is type specific and is illustrated by way of an
example on model 220 as follows:
Radio (A2)
CD player with changer (in trunk) (A2/6), with code (819) 6-disc CD changer
Sound amplifier (A2/13), with code (810) Sound System
Voice control system control unit (A35/11), with code (813) voice control system (VCS)
Telephone and TELE AID transmitter/receiver, D2B (A35/17), with code (855) TELE AID
Data transfer is conducted here in one direction only, i.e. the optical pulses for the voice control system control
unit (A35/11), for vehicles with code (813) voice control system (VCS), on model 220 pass through all
components connected to the ring, before arriving at the target components.
When the system is first put into operation, a system test is performed. In doing so the individual components
and their sequence in the ring structure of the Digital Data Bus (D2B) are registered by the component with the
master function.
A type-specific sequence is stored ex-factory. In turn, the storing of a sequence ex-factory means: if the radio
(A2) is taken from one model series and installed into another one, then during a system test the different
sequence of the components and an error message are filed in the diagnostic trouble code memory.
An error message is also filed if the radio (A2) is exchanged within a model series with different equipment
components. The system goes to the operational state regardless of the error message. STAR DIAGNOSIS
enables the sequence of the components to be subsequently altered in the Digital Data Bus (D2B).
The Digital Data Bus (D2B) is diagnosis capable via the data link connector (X11/4), except for models 129
and 202.
The operating principle of the Digital Data Bus (D2B) is the same for all model series; all that changes is the
sequence of components depending on the national version and equipment specification.
TABLE OF CONTENTS, FUNCTION DESCRIPTION OF DIGITAL DATA BUS (D2B) - GF82.00-P-0999ZZ
MODEL 129 as of 1.6.98, 163, 168 as of 1.9.98, 170, 202 as of 1.6.98, 203, 208, 210 as of 1.6.98, 215, 220
Data transfer, function GF82.00-P-2000A

2001 Mercedes-Benz ML320
1998-2005 ACCESSORIES & BODY, CAB Electrical System - Body - 163 Chassis
me
Saturday, October 02, 2010 3:30:04 PMPage 11 © 2006 Mitchell Repair Information Company, LLC.

Fig. 36: Identifying Radio (RD) Arrangement Of Operating Elements
RADIO MODE, FUNCTION - GF82.60-P-2001B
MODELS 163, 168, 170, 203.0 /2 /7, 208, 209.3 /4, 210 with CODE (353) Audio 30 APS
The ultra-short wave (FM), medium wave (MW) and long wave (LW) high-frequency signals are received from
the radio antenna mounted on the vehicle. The music, voice and/or data signals are modulated upon the high-
frequency signals received. The high-frequency signals are forwarded by the radio antenna over a coaxial cable
to the radio receiver in the radio and navigation unit (A2/56). The radio receiver demodulates the high-
frequency signals, i.e. it separates the useful information from the high-frequency carrier signal. The
demodulated audio signals are amplified and converted to sound signals by the vehicle speakers. Possibilities
for radio station selection:
Direct frequency input
Manual station search
Automatic station search (the stations on a waveband are played for approx. 8 s)
Station selection from the memory (6 stations for each frequency range)
Radio Data System (RDS), function
Many radio stations, e.g. (FM) transmit in addition to the program additional information such as the station
name, type of program (e.g. pop, culture, etc.), traffic station identification and alarm messages. This
information is evaluated and shown on the radio and navigation unit (A2/56) display, provided that:
the "RDS" function is switched on
an RDS station is set and received.
When an RDS station is received with a traffic broadcast in the background the abbreviation "TP" (Traffic

2001 Mercedes-Benz ML320
1998-2005 ACCESSORIES & BODY, CAB Electrical System - Body - 163 Chassis
me
Saturday, October 02, 2010 3:30:05 PMPage 58 © 2006 Mitchell Repair Information Company, LLC.

RADIO MODE, FUNCTION - GF82.60-P-2001GI
MODEL 163 as of 1.9.01 with CODE (522) Modular control system (MCS) radio USA with CODE (357)
Navigation system - additional unit with CODE (818b) Single CD player - additional unit with CODE
(491) U.S. version
(except 210.2)
except code
352a
Antenna amplifier module,
location/task/design/ functionModels 203.0/7,
209.3GF82.62-P-3105PP
Model 203.2GF82.62-P-3105PS
Model 209.4GF82.62-P-3105QA
Additional fan for radio/navigation
unit, location/ taskModels 203.0/2/7 as
of 1.6.03GF82.61-P-4110P
Rear window antenna,
location/task/design/ functionModels 203.0/7,
209.3GF82.62-P-3106PP
Model 203.2GF82.62-P-3106PS
Windshield antenna,
location/task/design/ functionModel 209.4GF82.62-P-3112Q
Sound amplifier,
location/task/design/functionModels 209.3/4 with
code (810) sound
system
Models 203.0/2/7 up
to 23.4.04 with code
(810) Sound systemGF82.62-P-3100Q
Models 203.0/2/7 as
from 24.4.04 with
code (810) sound
system, except code
(498) Japan version,
except code (494a)
USA versionGF82.62-P-3100PM

2001 Mercedes-Benz ML320
1998-2005 ACCESSORIES & BODY, CAB Electrical System - Body - 163 Chassis
me
Saturday, October 02, 2010 3:30:05 PMPage 60 © 2006 Mitchell Repair Information Company, LLC.

manual station search is activated by actuating the "joystick "to left or right. The station search feature
stops at the next station found, even when the" joystick " continues to be actuated.
Automatic station search with scan function can be activated by pressing the multifunction " Scan " key.
Each station received in the frequency range is played for approx. 8 s This function is possible only in
the forward direction. When activated " Scan " appears inverted on the display.
Manual fine coordination
The frequency can be changed when the" joystick " is moved up or down.
Station selection from memory
For each frequency range (memory FM, AM ) there are 10 memory buttons available. Press button of
number block approx. 2 s to store a station. When a station is stored it is confirmed by an acoustic signal.
Any station stored previously is written over.
In the frequency range WB (weather forecast) 7 stations are preset. These stations can be called by
momentarily pressing the desired number of the number block.
Station selection with frequency input via number block Pressing the" *" button followed by actuation of
the number keys allows direct entry of the desired frequency. Undesired entries can be erased with the"
Clear " button.
Station selection from the FM or AM station list by pressing the multifunction key" List " all stored
stations in the momentary frequency range are listed. Exit station list by pressing FM or AM
multifunction key .
Automatic storage
The "Auto" multifunction key (when pressed for longer than 2 s ) starts automatic storage of the 10
strongest stations in the corresponding frequency range. The stations are stored according to the strength
of the received signals in decreasing order.
CD-PLAYER MODE, FUNCTION - GF82.60-P-2002B
MODELS 163, 168, 170, 203.0 /2 /7, 208, 209.3 /4, 210 with CODE (353) Audio 30 APS
CD's can be played on the CD drive integrated into the radio and navigation unit (A2/56) or with the CD player
with changer (in glove compartment) (A2/6). The audio data are transmitted over the Digital Data Bus (D2B).
The CD disk drive is a double-speed standard CD disk drive, which is suitable both for pla
ying back audio CDs
Volume/tone adjustments,
function GF82.60-P-2003GI
Antenna system (AS),
location of components GF82.62-P-0001-03D
FM/AM antenna amplifier,
location/purpose/
design/function GF82.62-P-4101A

2001 Mercedes-Benz ML320
1998-2005 ACCESSORIES & BODY, CAB Electrical System - Body - 163 Chassis
me
Saturday, October 02, 2010 3:30:05 PMPage 62 © 2006 Mitchell Repair Information Company, LLC.

and for reading and loading navigation data from navigation data CDs.
A special navigation CD must be inserted for navigation purposes.
The CD player integrated into the radio and navigation unit (A2/56) provides the following audio functions:
Fast forward or reverse (music search) The music played is audible during fast forward or reverse.
"Scan" function
Each track on a CD is played for 8 s. After a complete run through, the scan function is automatically
terminated.
"Random" function
All the tracks on a CD are played according to a random selection.
"Repeat" function
The current track is repeated.
"Display" function
The number and elapsed playing time for the current track, the total playing time and the number of tracks
on the CD are displayed.
Each CD includes a permanently stored table of contents (TOC record). The table of contents (TOC entry)
contains information such as the number of tracks on a CD and the CD's total playing time.
CD playback is automatically interrupted by the following functions (pause function):
Traffic messages and public warning messages over the radio data system (RDS)
Incoming telephone calls
CD playback is continued at the position at which the interruption took place. No part of the track is skipped
during the pause function.
The CD playback volume is only reduced during navigation system voice output.
CD player with changer,
location/task/design/ functionModels 209.3/4GF82.64-P-3113Q
Models 203.0/2/7
with code (819) CD
changer 6 discGF82.64-P-3113PA
Models 163, 208,
210 with code (819) GF82.64-P-3113B

2001 Mercedes-Benz ML320
1998-2005 ACCESSORIES & BODY, CAB Electrical System - Body - 163 Chassis
me
Saturday, October 02, 2010 3:30:05 PMPage 63 © 2006 Mitchell Repair Information Company, LLC.

CD-PLAYER MODE, FUNCTION - GF82.60-P-2002GI
MODEL 163 as of 1.9.01 with CODE (522) Modular control system (MCS) radio USA with CODE (357)
Navigation system - additional unit with CODE (818b) Single CD player - additional unit with CODE
(491) U.S. version
Fig. 38: Identifying CD
-Player Mode Function
CD changer 6-disc
Sound amplifier,
location/task/design/functionModels 209.3/4 with
code (810) sound
system
Models 203.0/2/7 up
to 23.4.04 with code
(810) Sound systemGF82.62-P-3100Q
Models 203.0/2/7 as
from 24.4.04 with
code (810) sound
system, except code
(498) Japan version,
except code (494a)
USA versionGF82.62-P-3100PM
Additional fan for radio/navigation unit
location/ taskModels 203.0/2/7 as
of 1.6.03GF82.61-P-4110P

2001 Mercedes-Benz ML320
1998-2005 ACCESSORIES & BODY, CAB Electrical System - Body - 163 Chassis
me
Saturday, October 02, 2010 3:30:05 PMPage 64 © 2006 Mitchell Repair Information Company, LLC.

The radio and navigation module (A2/56)has various optional possibilities for the CD player mode.
CD mode with single CD drive (optional)
The radio and navigation module (A2/56) has an integrated CD drive as an option (code 818) intended for
playing audio CD's . If the radio and navigation module (A2/56) is equipped with a CD drive for navigation
(Code 357) as an option, it is also possible to play audio CD's . (However, during the navigation mode it is not
possible to play audio CD's Opening the operating and display module "(Open " button) allows access to the
CC slot and CD slot.
CD changer mode (with code 819)
The CD player with changer (A2/6) is actuated by the radio and navigation module (A2/56) .
The control signals and audio data from the CD player with changer (in trunk) (A2/6) are transmitted via the
digital data bus (D2B ). The changer is actuated by pressing the "CD" button twice . (When single CD drive is
installed).
Insert only 12 cm CD's into the CD player with changer (in trunk) (A2/6) , also do not use 8 cm CD
adapter .
On sound system (code 810) the sound amplifier (A2/13) takes over final amplification of the audio signals.
The signals between the radio and navigation module (A2/56) and sound amplifier (A2/13) are transmitted
via the digital data bus (D2B ).
The amplified signals are output by the vehicle loudspeaker system.
If the vehicle is equipped with sound amplifier (A2/13) the radio and navigation module (A2/56) should
be coded correspondingly with STAR diagnosis, otherwise malfunctions can occur when reproducing audio
signals.
When a magazine is inserted in the CD changer it is checked and a table of contents is made up. When the test
is completed the system automatically switches over to the playback mode and starts with the first title or next
possible compact disc.
If the system switches over to the CD mode before the test is completed the system starts playback of the CD
which was presently being checked.
The radio and navigation module (A2/56) offers the following functions in combination with the CD player
with changer (in trunk) (A2/6) and/or single CD drive :
Scan function
When the multifunction " Scan " key is pressed each title on the current CD is played for approx. 8 s .
The function is terminated b
y pressing the multifunction " Scan" key again.

2001 Mercedes-Benz ML320
1998-2005 ACCESSORIES & BODY, CAB Electrical System - Body - 163 Chassis
me
Saturday, October 02, 2010 3:30:05 PMPage 65 © 2006 Mitchell Repair Information Company, LLC.