Theres lots of talk in the C class forum about "can we get a copy of the software on the dealers diagnostic system".

Rather then talking there, (and as I couldnt reply in anycase!) I thought I'd do a brain dump here :-


The MB star diagnosis system runs under Windows NT on a IBM laptop. HOWEVER, its not just software .. Its the software you see there, and a thing called a Caeser, which is a multiplexing/intelligent device that connects to the PC, and then there are various cables that connect to the different MB cars.
In fact, the PC sits in a special docking station with a large connector that connects to the Caeser. Ive seen dongles on the back of the parts system PC at my local dealer, so I suspect theres dongles and licence keys aswell.

I think the Caesar implements all the protocols that the different electronic units on the car speak. Most of the protocols are standard (defined by ISO and SAE), but the values used are only known ny MB, theres also one or two Mercedes home grown protocols.

MB will sell you the systems in the USA [but set so you cant disable safety related features] see www.samstagsales.com/star_diagnosis.htm and houns54.clearlake.ibm.com/solutions/industrial/indpub.nsf/detailcontacts/star_diagnosis for more info. No one said it would be cheap though

Im in the process of releasing an open-source vehicle protocol implementation and Scantool for LINUX , but (a) its a few weeks away and (b) it doesnt do *anything* mercedes specific since I have virtually no details of what paramaters mean what on the MB control units. If we are lucky there'll be enough people like me out there who will work out the rest and add a nice friendly graphical interface to it all.

At least those with Linux and a cheap adapter will be able to reset their "check engine" lights and read the fault codes though ...

 

Richard, excellent information ! Thanks...

 

Good info Richard!

So what kind of protocols/parameters can you program on this caeser? Just curious as to what it can program??

Thanks again Richard!

 

The caesar seems to be a device with various standard interfaces and a multiplexor that allows those interfaces to be connected to the various pins on the mercedes multi-pin connector (under the bonnet) or the OBDII connector (near the drivers feet).

OBDII is a US standard, which has been around for some years, for a scantool to connect to an engine management system and get certain data about faults, emissions etc (the same standard defines how the "check engine" light behaves, and the format of the OBDII connector. (Europe has now followed with EOBD which is the same effectively)
The standard allows for one of 3 different electical interfaces, ISO9141, SAE-J1850 VPW and SAE-J1850 PWM. Most european/japanese cars use the first standard and Ford/GM use the latter two (cant remember which uses which)
There are two other important electrical standards, ISO14230 which is an extended ISO9141 and CANbus.

The OBDII connector has pins reserved for each of these types of interface, and a bunch of spare pins reserved for the manafacturers own use [which on MB's are all ISO9141 interfaces to different groups of systems].

I beleive the ceasar has ISO14230 and CAN interfaces in it, and therefore can talk ISO9141-2 and 14230-2 for talking to most controllers and a MB standard that uses the 14230 physical interface (for talking to things like the gearbox controller), and CAN for talking to everything else.

Mercedes have intelligent control units (i.e ones with fault memories and that connect to the diagnostic systems) for just about everything. Certain things act as "gateways" to others, for instance the radio/comand acts as a diagnostic gateway to the CD, Phone, Voice system, and the Electronic ignition switch (EIS) acts as gateway to all the blocks of switches (upper control panel (UCP) , lower control panel (LCP), front and rear door-control modules (DCM), and the front and rear signal aquisition modules (SAM))

I hope that make some sense.

 

Richard tell me if this helps or not. I have a Snap On 2500 vehicle scanner. It is a multiple layout hand computer that uses different chip cartridges for different makes, models and or series. When I bought my wife's E430 I checked into the cartridge for my scanner for Mercedes. I spent just less than $600.00 for the cartridge. It came with all the MB specific cables, and a very large book, as to how to troubleshoot all the vehicles the cartridge covers. Checkout the snap on site to see what the scanner is capable of. If there is any info there I can help you with, I will.
Regards,
Randy

 

Thanks Randy, at some point Im going to have to buy one and fiddle [to work out exactly what the MB specifics are for certain things] for my project. My [now defunct] MB dealer let me spend a morning with his star diagnosis computer and my CLK [and my laptop and software] so I worked out how some of the stuff worked and what control units talked what protocols etc.

I'll go look at the snapon web site.

 

Randy

Did your scannner come with the MB 37 pin connector aswell as the OBDII connector ?

Regards,

Richard

 

Richard I have about nine special harnesses for the MB, unique from the general Domestic, and Asian cartridges.