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Hey folks, have a "timeline" question for you W140 experts. I used to have a 1998 CL500, which I understand used a CAN network for vehicle management. I'm looking to buy another 140-chassis car, and heard that the CAN system was only on the other cars, and was supposed to be better than whatever was in the cars before. I've run across some earlier cars (1994-1995) and just want to make sure I get the best bang for my buck.

Does anyone know what model year the CAN system went into effect, and any experience as to whether it really makes that big a difference in the way the cars run? Any effect on serviceability?

Thanks!
Eric
 

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There is a CAN system in W140 cars with OBD.. It is slow has some code problems and is not compatible with newer can based modules. There is a protocol paper somewhere in my stuff I think.. If you did a complete swap on all the wire based systems then you may have a good chance of making it work.. the older system is the bio-degradable wire covering..not the best move by MB..
 

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Thats all stuff up to 96 i think..
The stuff with the SOYA based wire covering .. was what I was talking about.. so syljua perhaps you could explain the protocol to atruckerdaddy Like when it went from OBD to OBD1 then to OBD2 and to the universal P code system we have today.. Then you can tell him about the none swapable redundency code system introduced by MB and the pairing system that was introduced in the late OBD1 early OBD2 system..Because that will affect what units he can use ..
 

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9 and counting - 140, 129, 126, 124 and 107 Chassis
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Discussion Starter #6
My head hurts...

Didn't mean to open Pandora's Box here folks...but definitely a lot to consider. Sounds like anything from 96 and up is the better - or should I say, easier to work with - choice?
 

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I would say so..Pre 96 cars are a labour of love or hate.. my simplest car a 1927 RR phantom 1 the most compex I ever owned was a Mitsubishi EVO I keep the 600 because I have shed blood working on it and I have the scars.. and I know it will drive through a truck and I will get out on the other side..also She (who must be obeyed) likes to arrive unflustered and relaxed..
 

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1998 140.070 CL500, 1966 406.121 U65
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so syljua perhaps you could explain the protocol to atruckerdaddy Like when it went from OBD to OBD1 then to OBD2 and to the universal P code system we have today.. Then you can tell him about the none swapable redundency code system introduced by MB and the pairing system that was introduced in the late OBD1 early OBD2 system..Because that will affect what units he can use ..
While I doubt that atruckerdaddy should be exposed to the internal workings
of the electrical system of the W140, I will try to explain what I mean.

OBD, OBD1 and OBD2 are the protocols/interface for reading out diagnostics information, while CAN is the interconnecting protocol between the modules.
Again, all W140 use CAN for communication between modules.

When you are talking about "units he can use", I guess you are referring to diagnostic
equipement? Yes, the OBD2 can have pins for tapping into the 2 wires, high
and low of the CAN network. Not sure if you can use that via the OBD2 plug on the
W140, though.
On-board diagnostics - Wikipedia, the free encyclopedia

Sidenote;
A metaphor to this could be having lots of computers interconnected with
ethernet cabling. To diagnose why one of the other computers does not behave
as expected would be to ask, via some protocol, "what's wrong?", and get
a answer back, like, "hey, my hard drive is broken. I cannot continue".
That communication is then done over, for example, TCP/IP over ethernet.
If the other computer does not answer at all, one could sniff TCP/IP packets on the
ethernet, to see if the other machine is getting packets, is answering at
all, or answering with corrupt packets. That would be analog to reading the
signal on the CAN bus.

To me, it seems like atruckerdaddy wants to know which vintage
of W140 to buy? I would recommend the latest, less problems.
As for repair work on a vintage, and the possibility to mix and match module,
I think thats a far fetched problem senario.

Does anyone know what model year the CAN system went into effect, and any experience as to whether it really makes that big a difference in the way the cars run? Any effect on serviceability?
No, the CAN has always been there, and whether its available in the OBS2 connector
or not, it can always be tapped into directly on the wires, and read there. Have
a look here for an example of that;
Real-Life Diagnostics - Corsa No Start

br,
syljua
 

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As usual you miss out all the fun bits like the first OBD system pre w140.. the fact that the code was so slow that often the faults did not register and clear and sent false information to the system..OBD not obd1 or two was so complex the engineers at MB had great difficulty in making it work on any engine with more than 6 cyls.. but this is early stuff 70's..and 80's..slow processors and a ring main type buss.and none standard code addresses with different lengths from 8 to 16 bits at different times and different buss speeds on the buss to make discrimination easier.And dont quote wiki at me I can put whatever rubbish I want up there and people like you will believe it..

when you say equipment he can use you have totally missed the none backward comparability issue.. and the Pairing issue with todays can modules the ten strikes and you are out system.. First OBD had no recognised diag plug.. OBD1 has the 39 pin plug OBD 2 has the 16 pin standard unit and the standard P code universal reading as agreed by the industry.. But early OBD1 has no such standard.. nor has OBD.. so go get your hands and your scope probes dirty oh and you will need a twin beam scope and a recorder to read it properly.. your analogy of the TCP network is a complete waste of brain power the can units keep reporting the fault until the fault is corrected and then cleared from memory..The early systems would stack the simplest fault codes supposedly in order of importance.. however this sometimes led to system lock up as the faults were read after the car was stationary and would flatten the battery trying to clear the backlog on a looping system so some faults were never read and the cause was never detected even when the system was interrogated.. The classic on obd1 is the left rear brake or speed sensor..reports but is never or very very very rarely at fault.. you might give me your explanation for that..I know the answer but it took me several weeks of recording the data to work it out.. so over to you I await your explanation.. ..I could go on but I question your ability to get to grips with it..
 

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1998 140.070 CL500, 1966 406.121 U65
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And dont quote wiki at me I can put whatever rubbish I want up there and people like you will believe it..
And what part of the quoted wiki page is false information?

so over to you I await your explanation..
Sorry, but I really do not have to explain that the 140 has had CAN in all years.

..I could go on but I question your ability to get to grips with it..
Sure, we have been there before;
http://www.benzworld.org/forums/w140-s-class/1369680-ecu-et-al.html

syljua
 

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140s use a serial link canbus (vs fiber on current vehicles) it is a collosal pos but it rarely goes wrong. however mercedes was just experimenting with it so they tried to get it to do a bunch of things that are normally achieved with a 2$ relay.

so when something goes wrong, it can be mindboggling to figure out why. it makes no sense half the time why they used it to control xyz function
 

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No you thick head

When you are talking about "units he can use", I guess you are referring to diagnostic
equipement? Yes, the OBD2 can have pins for tapping into the 2 wires, high
and low of the CAN network. Not sure if you can use that via the OBD2 plug on the
W140, though.

the units that send the information ...If you are going to argue with me..

YouTube - Pulp Fiction - English Motherfucker Do You Speak It

And Wiki did not even mention early OBD..Could that be because they know nothing about it ?
 

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p1747,p0600 1996 s420

hello gentleman. We here in massachusetts are working on a 1996 s420 140 chasis. We have been suffering terribly with an extremely stubborn can comminiucation situation. Most of the time when the vehicle warms up but not always the EPC/ASR lights along with a blinking fuel and low fuel lights illuminate. When this happens the transmission goes into limp. Now the codes in the ecm are p1747,p0600 which are no communication with the trans or the tracs. In the trans it says no communication with the engine or the tracs. In the tracs it says no communication with the engine or the trans. We have physically checked every inch of the can lines in the module box. We have replaced all the control units including the base module. Most recently we even have replaced the instrument cluster. Boys please if any of you have any insight on this situation please, i would be most grateful. Our email is [email protected].
 

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216 with everything. 2002 SL500 with everything. 2009 SL500 with everything.
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Your car you say it is 1996, if it was built after 06-96 then it does have a full blown CAN as we know it today (if it has the 722.6 gearbox, then full can).
One of the big problems that happened was that in the connectors that couple the various ECU's together had some poor connections.

CAN signals carry no current at all, therefore stand no chance of any minute arc that can render the connections good again, in the event of a poor connection.

This was evident more on the gearbox ECU with the 722.6 box where the CAN connection were very poor with the result that non plausible codes would be read out and the cars doing odd things like locking up and other interconnecting ECU's miss behaving.

Before I start on any of these faults I will clean the gearbox ECU connectors with a good non drying switch cleaner. This is a known problem and listed in WIS, the CAN connections are the 2 end ones.
 
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