DIY: REAR SAM W203(AND MANY OTHERS), LOW COST REPAIRING
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Few months ago,during a battery replace,my rear SAM gone off, (was an early 0025459701, which are not in production any more).I replace it with the equivelant newer 2035453401(or2095450101),in the official stealers + star programming bla-bla,...and 350€-400€ the cost.Also i bought a used one [0025457801(it covers a lot of MB models incl.w203- is similar to 0025459701),for 50€ for reserve].Finaly , got from a friendly workshop, a blown ..701one for free,to practice myself.

Then i got mine bad one,and when i had some spare time,i tried playing, to find a cheaper solution for this common w203 failure.Here are the results:


SYMPTOMS( After battery replaced,or charged,or jump up...)
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Faulty display visit workshop in the cluster panel
No fuel gauge indicator
No turning signals
No wipers
No reverse lights
No boot opening
and some others that rear SAM controls

NOTE:
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Some guys wrote in the forum that,the SAM's programming is getting lost only ,and with a SAM's reprogramming in star diagn. everything is ok again .But unfortunatly it seems no true,because all the cases i discuss with, MB official mechanic,and some other MBindies,all replaced the rear SAM,us mine.
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LAST MOMENT INFO:
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By AUTO FIX

This sam problem, as you have shown, is nothing more than a software issue. There is no hardware fault. It is actually possible to program the old MCU with a “virgin” dump and it works fine. This is basically what codecard are selling.

This situation is true of a lot of modules in Mercedes and other makes. Imagine having to buy a new PC every time windows crashes.
In some cases the boot sector is corrupt so there is no way to flash serially but sometimes it is possible. When the boot sector is damaged the only way is on the bench with a programmer. A collection of virgin dumps and the knowledge of how to manipulate existing ones is all that is required.
Around the world there is a small community of techs who share solutions for these type of problems, especially on common problems, eg EIS’s.

Some modern automotive technicians have a range of eeprom programmers, hot air stations etc in their arsenal of tools. This allows tuned in independents to be far more efficient (cheaper) than dealers as the dealers will never do this level of work. In reality Mercedes should solve this problem therselves.
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A: SOLUTION(the hard one)
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HEART OF THE PROBLEM:
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The affected part when this happened, is a 64pin processor inside the SAM. Motorola's MC68HC908AZ60 2J74Y processor. (pdf *)
If it is the 2035453401 and newer SAM,you are lucky just unclick the rear cover and the chip is visual in the side(ph:A1), ready to replace it.

Instead, the early SAMs like 0025459701,0025457801 is a headache.When you open the cover-surprise- you find the opposite side of electronic parts(ph:294),so processor is underneath, and you have to dismalt all the SAM ,and desolder the whole base to reach the chip .But don't worry,just do a cut (19x5cm) in the plastic base where the label is(ph:293), with care. [you have more than 1cm underneath clearance all the way ,except in the red arrow (ph:293 ), attention!],and voila ,the chip is in the center, ready to proceed.

SAM'S REMOVE:
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Remove keys.
Disconnect (-) battery's terminal!!!!!! (the SAM anyway is blown)!
Remove plastic clips, and take out boot's rear plastic protector,in order to remove the half left side vertical carpet.Now the SAM is in clear view.Undo the bolt in the top and lying down the SAM in front of it, by turning it,now get it out of its base, and your are ready to unplug connectors.Note which one goes where,and remove it.Also remone from its rails, the anti-thieft tow sensor & a vacuum sensor too.
Put all connectors in polybags to keep it clear(ph:299).

TOOLS:
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Although finally,i replace the chip with proffesional tools(soldering base and desoldering tool-are expensive), i did exactly the same job with amateur tools & self made desoldering tool (ph:304,5,7,16) ,in the second SAM, for amateurs (like me in this case).Also there are some other ways to remove & solder the chip.It is in your choise.

a) A 20watt Taivan soldering iron (with two tips,one pinpoint-one hoof.)
b) Thin no-flux solder 1mm
c) Liquid no-flux cleaner(important)
d) Desoldering braid 1,5mm.
e) Alcohol for final clean.(ph:297)

PRECAUTIONS:
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Watch carefully these youtube videos* and more, do some practice to a useless processor of a dead PC, for desoldering and soldering before attempt to your new already programmed processor.

If you deside to do it by yourself and select the desoldering method as in photos(ha-ha),you must get a refaced (with a 16mm iron bar), 3/4''to 1/2''bronze plumber's connector, with a 1/2'' tap on it,( do a 5mm hole on top, to insert -the well welded with instant UHU- wire on top of processor,prior to raise all(ph:310), after heat apply),heated to 450 celsius,to maintain enough amount of heat, for desoldering 64 pins at once.You must leave it approx.5 secs seating square in top of the chip,before starting to raise it (ph:310).The copper one(ph:309),does not work at all,too little thermal amount.Notice,the around the chip solder(ph:308), before the heated bronze insertion(ph:310)),which after melting ,equalise thermal amount around the chip and make desoldering, easier and safer .

After chip removed(ph:311),desolder the base pads with desoldering braid(ph:315).make a perfect pin/pad align, and you are ready now to solder the new processor(ph:312,13), following video's soldering tips.

IMPORTANT:Before start desoldering the old and soldering the new,note the marking point for correct reposition.(blue arrow ph:293)
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Degauss yourself and go on,.... but...........!

BECAUSE it is very easy to DISTROY the base pads & so everything,is far CHEAPER and BETTER to pay a local PC repairshop, to do the job for you!!!

ANYWAY THIS IS A JOB,FOR AN ELECTRONIC'S PRO.

THE TRICK:
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Visit this site * to order on-line your new already programmed processor,95€ in front of your door(ph:296,8),mentioning your SAM part no:,and do all above.
This solution is cheaper,than some other ,who need to send them the complete SAM for repairing in excange, and pay for repairing and two p&p.-
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After finishing the job(2 hours),put back everything in reverse ,weld the cutted plastic piece with melting plast-gun(ph:317),remove keys, and when you are ready to connect the battery's (-) terminal,do it steady with confidence at once,not too fast-not too slow!!(personally i think the SAM's failure occurs during disconnection,not when reconnect the battery).Cross your fingers and start the engine,if you did it the right way, everything will work fine. Mine did!!!

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*
Order on line:
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http://www.codecard.lt/electronics/2.../prod_127.html

Processor info:
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http://sci.tech-archive.net/pdf/Arch...2/msg00177.pdf

Videos:
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http://www.youtube.com/watch?v=V_cDV...eature=related
http://www.youtube.com/watch?v=33BrKvRb6M8

Here are photo's Mbytes:
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http://s594.photobucket.com/albums/t...on=tageditmany
(there are more photos,ask)


B: SOLUTION(the simple one)
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If you find a cheap used SAM (around 60-70$), then you can peplace it by yourself,and reprogramm it,visiting the local MB dealer for 60$.(total cost 120$).Unfortunatly the common second hand SAM prices, are about 150-200$,(here in Greece).They know exactly what they sale!.

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GOOD LUCK.
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Comments suggestions wellcome.
GUS.-

 

Gus, you are the MAN! Great bit of research, and full documentation to fix this common problem. The Mot HC908 is not very well protected from DC inrush, and fails quite often.

I was laughing out loud at the surface mount desoldering aid constructed from a brass pipe fitting. Very clever. If all your neighbors were that smart, Greece would rule the world.

Many thanks for the considerable effort to make this fine contribution.

 

Thanks Moviela,
you hit the target,we have similar ways of thinking and sence of humor.! I add a ( ha-ha )!!! to the post, for this.-

 

Your photobucket link takes me to the home page.

Whew! Some work there. I think that anyone who is looking at the huge cost of a new SAM will do this. I know I would.

 

Well you went the hard way
Sure i would just search for a used unit and end of story! Glad you made this walkthrough

 

Ed,
Try this
http://s594.photobucket.com/albums/tt26/gusvlachos/

I don't get the point in the metal bits, is that to
keep the circuit cool while soldering?
It's quite remarkable you were able to do this without
detroying the board.
Multi layer, surface mount stuff is all but impossible to repair...
or so I thought....

 

In thinking about this. Is there a particular way that we should reconnect the battery if we disconnect it?

Is there a way to use some type of increasing voltage when we reconnect the battery ground? Or wait, are we connecting positive first....

Arrr.

 

Instead, metal bits are for desoldering the chip. You have to do it fast (5 sec), w/o too much overheat (450 c), otherwice the board 'll ruined.Watch the video, with the proper tool, for this job.

 

Ed,
you open an issue for future discuss. Why this is happened to sam's when dis/reconnect the battery?.Personally, i think has to do with inductive current/inrush, during disconnection phase, (remember the old distributors, contact braking points principle).This has to do with the ( contact time-speed actualy) of dis/reconnection, and the weak sam's protection , as Moviela described before .

 

Great work Gus !!!!

 

Thanks Glyn, you helped a lot in the past !!!
Gus.

 

The accepted method is to have a 2nd battery, a motorcycle battery will do, to connect to the lead while you disconnect the battery, but of course that means you still have voltage...

Basically the issue is caused by current surge.
So for me, I always disconnect the ground 1st and
make sure I don't arc too much.
Each time you arc, that a giant surge.
So make sure everything in the car is turned off, like interior lights, radio etc. when disconnected/reconnecting and try to do it very quickly and minimize any sparking.

I've often wondered if a capacitor or something that would allow the current to ramp up slowly might be the ticket. Perhaps a potentiometer, ramp up the voltage manually controlling the surge?

 

Exactly ,
but for some repairs you have to cut -off electric power.
Do you remember the capasitors (reverse current), in the old fashion distributors?!!

 

Efharisto Gus

 

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Wow!!!!

 

Very interesting!!

 

I have problem only with rear lights. The processor A1 in my rear SAM work, but something else doesn't work. I heard for some drivers for rear SAM, Is this true? And what are these drivers? Thank you.

 

It's unbelievable.

In my experience,the drivers circuit have more failure,and the control circuit have less failure.

Without special tools,I can change that chip.But I worry about the program.

 

This has saved me some headache THANKS BRO

 

You've managed to change the chip?

 

Hello Gus.... thank you for some excellent diagnosis. I have been a drivability/MANAGER FOR OVER 32YRS. Foreign, Domestic, European, etc. All makes All Models. Nothing scares or intimidates me....... Well until I bought one... lol..... I believe Mercedes Benz is alot easier than a Bmw, and more intelligent than AUDI or Volvo.....lol ....I have a question on w203 ....my rear sam is of course located left rear trunk. It is a 2035453401, you had mentioned it was one of the easier Processors to repair(I believe you said lucky)..... Well ...please correct me if Im wrong, because I have to dissemble the rear sam on the 2035453401 to get to the chip (prom) taking the back cover off just reveals a board NO prom or whats necessary to repair ask if . My question is do you , on that rear Sam as mentioned.....have you ever disassembled to repair ...Correct me if Im wrong, but it still requires not cutting but total disassemble . I have almost taking board out but came to a stopping point to ask before I find out exactly is holding board. Dont want to do unnecessary patients and sweating lol. Get back to me ... Thanks Randyz

 

Hello, I'm having issues with my front SAM I believe. 2010 e550 w212. I have tried contacting codecarx for a replacement processor with no response.

What is the compatibility of used front SAMs to replace? I have searched the part number in EPC and the specific part number for mine is not very common. Thanks.

 

 

2010 GL450 X164
vin# 4JGBF7BEXAA536910

i need to repair my rear SAM can’t find a technician , currently my fuel gage doesn’t work , my rear tailights flash like strobe light when pedal pressed. Keyless entry doesn’t work either

regards,
joseph

 

send a PM. I have tons of used parts here.