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Created: 30 Nov -0001

Last Updated: 4 May 2008

Mercedes COMAND Diagnostic (“Service”) Mode


Version 1.6 10 Dec 2008 – Add more info about interlocks

Version 1.5 7th October 2007 – Add info about Comand 2.5

Version 1.4 12th May 2007 – Correct links for new mercupgrades website

Version 1.3 25th March 2006 – correct CTEL2 value

Version 1.2 25th March 2006 – tidy up

Version 1.1 25th March 2006 – add “exit” instructions





Mercedes’ COMAND 2.0 (i.e. CD based COMAND) system has a whole set of hidden diagnostic menus.


Diagnostic mode is also available on COMAND 2.5 (the original S/CL class COMAND version with a tape deck) but will be subtly different to those described below.


These menus are useful when trying to ascertain if there is a fault with your COMAND system, however, nothing can be altered from these menus.


To enter diagnostic mode, press SYS and then select the AUX input by turning the right hand rotary knob to highlight Aux and pressing the rotary knob.


Then hold down the following 3 keys for about 10 seconds.  MUTE, 1, 3


(NB, on the Comand 2.5 do this in TV mode as there is no AUX mode)


You will then see the following screen: -




On COMAND 2.5 (old S-Class/CL units), it may be possible to enter this menu if you select TAPE input as there is no Aux input.


The rest of this document describes what information is in the various screens/menus that can be access in Service Mode.


The RET key acts as a “previous screen” key – so to exit service mode, just hit the RET button when the menu above is showing.





Entering this menu allows you to see the software and hardware versions of COMAND.

Select the menu you want with the right hand knob, and use RET key to go back to the previous menu list.


Here is an example from the Processors menu, this is a COMAND 2.0 E class unit with the MY2001 software update applied



The most useful screen here is  ‘Infos” as it tells you if the vehicle is seeing the speed impulse and how many satellites are being received.  If you have a different looking Infos menu, it is because you have not applied the MY2001 software update to COMAND – which you should so.





TUNER menu


This returns you to the FM/AM main screen, but also shows an extra line showing the currently tuned stations frequency and signal strength (0-10).  Remember that in Europe the main line normally shows the RDS station name.





This allows you to see various configuration items, including the error list, to reset the COMAND system, and to look at the D2B status.




The Error list initially shows the list of errors that the dealer’s Star Diagnosis machine would see, holding MUTE and 1 switches to  the internal list. MUTE and 4 returns to the original list, MUTE and 0 clears the error list.



The meaning of  the SAE-Code in the error list can be found at: - COMAND error codes


The Type field is part of the error code, and in the list of error codes is shown after the / in the error code – For instance B1912/8  would have B1912 in the SAE-Code column and 0x0008 in the Type column.


The Cnt figure is useful as it tells you how many times an error is occurring. The State value tells you whether the fault has happened Previously or if the fault is currently Active.


Selecting System Reset resets the COMAND unit.


The D2B components list shows what is Actually found on the fibre optic bus, and what the system is Configured on the bus. If the unit has been properly configured by the Mercedes dealer, then these should match each other, and match what extra options you have in the vehicle.



The 3 digit numbers shown are: -

            1C8                 COMAND

108                  Digital BOSE AMP

190                  CD Changer

0F0                  Phone

0F1                  CTEL2 (e.g. 2nd phone in S class)

1F8                  Voice Recognition

1B0                 Satellite Radio Module (USA)

0E0                  Teleaid Control Module (USA)





This shows how various options are configured on the COMAND system.



There are various tickboxes,

            TV-Tuner                    TV tuner is enabled – enables TV button on US units

            Telephone (expand)     Enables SMS functionality on phones

            Telematic                     Enables TCS (nothing to do with TMC)

            Telematic over D2B    ditto

            Analogue Bose            Tells system analogue bose amp connected

Combi-Self-Aligned    Tells COMAND whether the instrument cluster will self centre any text that is sent to it or not


And, on the bottom line is 6 alpha-numeric digits (hexadecimal) (20 6D 04) in the above case - The last digit (4) in the above example configures which interlocks are in place to prevent the TV being watched whilst the vehicle is in motion – the other digits control various features, some of which are in the tickbox list.


Here is a table of what some of those interlocks mean.


First Byte (20 hex in above)

Bit 7 (MSB)

Analogue Bose

Bit 6

SMS Sending disabled

Bit 5

Always Set

Bit 4


Bit 3


Bit 2


Bit 1

Telematics (EU) / Starguide (USA)

Bit 0 (LSB)

TV tuner


Second Byte (6D hex in above)

Bit 7 (MSB)

Telematic via D2B

Bit 6

Telephone with expanded functions

Bit 5

Instrument cluster with self centering text (combi self aligned)

Bit 4


Bit 3

Always Set

Bit 2

Always Set

Bit 1


Bit 0 (LSB)

Always Set



Third Byte (04 in above)

Bit 7 (MSB)


Bit 6


Bit 5


Bit 4


Bit 3

TV disabled at speeds > 10km/h

Bit 2

TV disabled at speeds > 2km/h

Bit 1

TV disabled if not in Park / Neutral

Bit 0 (LSB)

TV disabled if handbrake off



Also on the bottom line is the setting telling the COMAND how many impulses per wheel rotation the car will send the COMAND unit, this is also in hexadecimal, so 30 means 48.  Remember that with some cars the speed is sent over the car’s network (CANbus) rather than with a speed signal wire, so in some cars this can be set to 0.


If this has been useful to you, please bookmark or use the links on the where you will find further information about COMAND and other Mercedes electronics.



© 2006-2007 R.P.Almeida /



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