R230 Front SAM question

[Lowe712131]

Thanks to the nice weather, have had a couple of days to play at fault finding on my SL55.
I can't get my STAR to talk to anything on the CAN B at all, I just can't get it to talk to the EIS. I though my STAR might be dodgy at first, but I can see engine, transmission etc.. in fact anything on CAN C.
I've checked, cleaned and sprayed all the multiplugs on back of EIS, under carpet (changed CANBUS connectors for new) and I am now working my way round the car, disconnecting all the major control units, cleaning and spraying all connectors with non drying switch cleaner (thanks Malcolm! )
I took the Passenger (UK) side SAM out earlier, checked for dry joints, broken tracks etc.. and in doing so noted there was a green coloured plug with both the CAN B and CAN C twisted pair wires going into it. All put back, no problem.
I've come to take the Drivers side SAM out now to do the same and there is no CANBUS plug connected to the SAM at all. There is a socket on the SAM for it, identical to the passenger side, but no plug attached. is this correct, or am I missing a plug somewhere? Can't immediately see any spare plugs in down in the housing, but just wondered if I'm looking for something that isn't there anyway? Any help or wisdom greatly appreciated.
Cheers
Simon

 

[television]

I have almost finished a DIY on the 230 can system, re your SAM, the SAMs are interconnected so only one coming in to one side.

I am cooking dinner right now

 

[television]

What is the problem on the car please

 

[Lowe712131]

Front SAM R230

Hi Malcolm, thanks for the reply, and I've seen the CANBUS test instructions, very helpful thanks.
The problems I currently have are :-
Keyless go not working (missing card issue - mentioned on a different post, so is a separate issue)
Parktronic Not working (not got onto that one yet!)
Comfort seats not working (I think they just need switching on in menu)
SRS Light on (took seats out last week, turned key on to test Canbus so it registered an SRS fault)
Just had a 'Service Brake' warning come up - I was concerned this was the dreaded SBC pump, but thankfully my STAR can connect to Can C and the warning code is for the Stop Light Switch, not the pump - the current cycle count is only about 10% of the max, and it does look like the SBC pump has been changed fairly recently.
The main problem I have is my STAR setup - it just will not communicate with anything on Can B. It is a second hand laptop & multiplexer I bought online so I have no comeback on it and I'm flying a bit blind, working out whether it's me doing something wrong, the car or Canbus circuit, or the unit itself at fault. I guess the simple way to test is get it on another Merc and see if I can talk to that Can B - a mate has just bought a SLK55 so I might pop over to him and have a go!
So at the moment, simple things light resetting the SRS light or turning the comfort seats on cannot be completed as all I get is 'Cannot communicate with EIS' every time I try to get into any of the relevant menus.

I do have one, tiny ray of hope now - I was playing with the laptop last night and found the IP addresses for the multiplexer were slightly different to the ones shown in the video demo, so I have changed them. I don't know if this will cure it, so I just need an hour or two to get back on it again. Fingers crossed! Thanks again Malcolm.

 

[television]

You throw up some interesting points, my SL was an early one and no way could I go to head lamps or the comand in STAR, if I selected headlamps it would shut the whole thing down, Comand it could never find, the same STAR has worked perfectly on all other cars that have come into me, and it works fine on my CL500.

So STAR or car, only be trying on another STAR will you know

 

[Lowe712131]

Yes, it's frustrating it could be any one of three problems at the moment - guess I've just got to try and narrow it down one at a time. Not too fussed though, nice to know my SBC pump is OK .....for now!
Did the C Pillar seal job last week though, following your excellent DIY and I'm pleased to say it has worked perfectly, nice one Malcolm. boot is dry and not a hint of condensation inside now. I think it was a combination of the 3rd brake light and the C Pillar leaking, but all is good now. It's probably that environment that has played havoc with the Parktronic to be honest - I'm lucky the PSE pump seems to be OK.
Cheers
Simon

 

[television]

Have you tried going in the back door, the is go to communications and go to the CAN direct, it will show you the state of the bus and what is running.

 

[Lowe712131]

I've had a scope meter on the CAN connectors directly and can see the transmissions on both CAN H & CAN L, so there is definitely activity on the CAN B, I know that doesn't mean there can't be a problem somewhere on the system, but I should be able to get into it with STAR. More and more I am thinking it is an issue with my setup / multiplexer. I will have another play with it when I get back later this week, unfortunately work gets in the way again! Having one of these cars with issues is a great way of learning though, which is one of the reasons I got it - in a mildly perverse way, I'm actually enjoying it! :lol:
Cheers

 

[television]

Same with me as it was a learning curve, if you have activity on both lines it should be ok, what you do not want is any activity when the car is trying to sleep, so after some time after locking it should all quieten down.

I must add a few more words on the DIY on this sleeping part.


A hard one re the multiplexer

 

[Lowe712131]

Yes, I'm quite hopeful on the Multiplexer, at the end of the day a replacement won't cost tooooo much, so it's not a train crash if it is knackered.
I think the wake up situation is OK, I changed the battery a couple of months ago as voltage was a bit low and charge wasn't lasting (elec consumers offline etc.) and now it holds charge for weeks without use, so I'm fairly confident there isn't anything staying on when it shouldn't. I reckon the Parktronic issues may be the ECU or at the very least the connectors to it, I did get a printout from a diagnostic session last year with the car and almost all sensors were showing faults - that kinda points to ECU rather than sensors to me, as it is unlikely so many sensors would go down at the same time. With the wet atmosphere it had in the boot for so long, I'm surprised there aren't more issues (PSE pump, roof pump etc..). At least it's all dry now - just need a bit more time to strip the boot out and check/clean/dry all connections ...... oh, and a working STAR would help! :lol:
Cheers

 

[Lowe712131]

Finally! Solution to 'Service Brake' Problem!!

Well, it has been a long slog, but now have the definitive solution to my particular 'Service Brake' Warning. There are, of course, many other reasons for this to come on, but this is what happened to me.
I had recently changed the 3rd brake light, as the old one was cracked and letting water in. Not long after, I would get the 'Warning - Service Brake! Visit Workshop' message coming on after I pressed the brake pedal a few times. Connection to Star came up with the brake stop lamp circuit fault, however the switch and stop lamp were both brand new, MB parts. I ran out of options (and ability) looking for this, as my Star struggles getting onto CAN B for some reason (multiplexer still suspect), so I sent it in to Mertrux in Derby. I've had dealings with them in the past and they always seemed pretty good. Had some good, in-depth chats with the guys there and I went through everything that I'd done and noted on the car. I can only say they were great (makes a change to say that about a dealer!) Dean and John were superb and Dean in particular is incredibly knowledgeable and very fair. They had the car for a good few weeks, but only as I didn't need it and they just kept it at the back of the workshop and did bits on it as they had 'spare' time - once again, very fair.
I did tell them I suspected it may be the front, passenger SAM module at fault, as that houses the brake stop lamp circuit, but everything else seemed to be OK and I had checked all the connections, cleaned etc..
Anyway, after much searching, they found that when I fitted the new stop light, I had pinched one of the wires in the metal bracket (difficult to see when fitting it!), that had caused a short in that circuit and in turn blown the front SAM. They ordered a new SAM, fitted and tested it and I'm happy to say all sorted ..... even though it ended up being my own fault!
All-in-all a good result - had a couple of other little bits done too and the price wasn't as bad as I was expecting for the work that was done.
I can definitely recommend Mertrux in Derby if you have any problems - speak to Dean - good guy. 01332 290290.