Battery drain..SAM unit, control unit under drivers seat.

wildmann

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Battery drain..all of a sudden. Had vehicle recovery comp(roadside assistance) out a number of times( all happened over xmas) jump started car ok, would take it for a run to charge, but drain woould re-appear within a couple of days. Loaned battery charger from friend..removed battery to re-charge, however, his charger was faulty and s no luck. Called vehicle recovery company as I needed another jump start..they arrived and re-connected the battery. Car turned over, but by now..the removal of the battery, and possibly low power had now blown the rear SAM as once the battery was re-connected nothing worked, i.e. indicators, hazzards, wipers, washers, mirrors, boot release, petrol gauge, etc. Only thing that worked were the headlamps, heater, and radio..So SAM replaced(!) £390!. This did not cure the drain..re-occured 2 days after picking up from the repair shop. So, was told that it was a faulty battery, replaced the battery ..cost£70. Guess what, no joy..the problem returned around 3 days later, completly draing the new battery. Car just returned to me from the repair shop at a cost of £523!!! The problem..now resolved...WAS a faulty seat control! Total repair bill £983!!!!!!!!

Damn car..had many electrical problems with this car in the 4 years that I've owned it. I thought that Merecedes were supposed to be the dogs bits! I don't trust this car or any other merc! My car is one of the hundreds of thousand mercs that experience electrical problems. Had an E30 320i SE straight six petrol BMW before this..owned it for 11.5 yrs 150k miles..went like a dream..owes me nothing..this,blah!!!:mad:
 
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wildmann

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Addition..I think the rear SAM unit actually blew because of jump starting the vehicle. I should have just powered the battery for a short while, disconnected the leads then started the car.
 

mikestrivens

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Yes these cars do not respond well to being jump started or using boosters, the electrics are too sensitive.
 

Alex Crow

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that battery drain is well known, if you had asked here in the first place we would have suggested it. glad you have it sorted now though, and you might want to correct your car details - it cannot be a 1990!
 

television

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Yes as Alex we could have solved it for the cost of a seat controller, sadly very few MB engineers are any good with electrics, Alex above is an exception
 
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wildmann

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Many thanks for your replies guys. By the way, I've just corrected my vehicle details..I was obviously thinking of something else at the time..not sure what though.
Yeah, it would have been a great help if I could have got the answer earlier, possibly would have saved me a bit of time, and cash too.
To be fair to Television..he actually did help me on my previous thread.
I was the guy looking for help with a faulty display panel (not too sure of correct tech name for it) that would not go out/off. It's situated within the dash display, under the speedometer. At the time I also had a problem with the wipers, flashers, petrol guage, etc,...all not working. Television suggested a rear SAM prob..and he was spot on. But, all along, the main problem that started the whole knock on effect with me blowing the SAM, was this particular module. Sods law..I found the actual answer online the very day I had my car returned from the garage.

However, this forum and it's members, such as yourselves are mine of info, and so, I now find myself reading / studying it everyday.

By the way thanks to the rear SAM, a new battery and now a new module, I've just forked out £983 on repairs since the new year! I do hope that this not the start of an expensive year!

Once again, many thanks.
 

mingblus3

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I have just diagnosed the same problem myself, exactly the same symptoms.

I'm still not sure which seat it is as i've unplugged them both. However I found the advice on another forum which provides a cheap fix and I've yet to find the instructions as I'm not a member . Apparently the only loss it the memory function. Has anyone got this info and also can anyone tell me exactly
which plugs I can re-attach as I've got the SRS air bag lights on too.

Cheers
 

television

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I have just diagnosed the same problem myself, exactly the same symptoms.

I'm still not sure which seat it is as i've unplugged them both. However I found the advice on another forum which provides a cheap fix and I've yet to find the instructions as I'm not a member . Apparently the only loss it the memory function. Has anyone got this info and also can anyone tell me exactly
which plugs I can re-attach as I've got the SRS air bag lights on too.

Cheers
All items that have a memory can be bypassed in a way, battery drains are caused from the memory sections of these components, one can cut the memory wires this would mean that the drain would stop, but the memory would be lost. some on the 202 cars would join the memory wire to the main plus wire and still retain the memory, the drain only there with the engine on and running, so it does not matter
 

mingblus3

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How can this be done on w203 do you have any details on getting this done to still retain the memory. So far I don't have any instructions. To be honest I unplugged every connection to the seat but want to attempt to fix this.
 

television

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How can this be done on w203 do you have any details on getting this done to still retain the memory. So far I don't have any instructions. To be honest I unplugged every connection to the seat but want to attempt to fix this.

It needs some checking on the wiring diagrams for a 203,,,I did say above that this worked on some 202 cars, the other hard bit is that the 203 is CAN controlled
 

mingblus3

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Does anyone have a picture of the seat control module that is causing the problems. Under my seat I seem to have a couple of boxes. Is the memory module separate or the complete unit.

Or a part number for the replacement faulty part?

I really do need some help here, I've also been told there is a fuse box in the rear with 20Amp fuses. Possibly one for each seat and I could remove the fuse and leave the seat connected.

Should i be creating my own new thread on this?
 

television

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Is not it in the door and all one unit for the windows and doors
 

mingblus3

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But i've disconnected everything from under the seat. So you are saying that its to do with the buttons on the door panels, nothing under the seats?

I'm getting more and more confused. I think a part number would help but again when I google this I get mixed results.
 

television

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But i've disconnected everything from under the seat. So you are saying that its to do with the buttons on the door panels, nothing under the seats?

I'm getting more and more confused. I think a part number would help but again when I google this I get mixed results.

I am sure the ECU is in the door, I will check for sure soon and post back
 

television

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Well I am still sure that ECU 32/1 is in the door
 

Alex Crow

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it is indeed the ESA ECU under the seat that is the culprit, not the DCM (in the door).
 

television

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it is indeed the ESA ECU under the seat that is the culprit, not the DCM (in the door).

Thanks Alex not a good day, I tried on WIS but found the esa was the non memory version, and nothing on the removal, then lilian went missing and had to get the police to find her so I gave up
 


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