Thread: c-class electrics -front sam- + general

Hi, just wondered if you know and willing to share info to help sort a problem or two.

C class w203 late 54 c180k se auto saloon.
Was about to take for MOT yesterday and in my pre check, well to be honest scramble to get ready wasn't able to get windscreen washer going.
I've had a few other probs to do, mostly body work rads and air con and though I've know washer didnt work, never felt it could be more than a fuse etc. till now.
Well I've done the rest and got to the washer & despite reading numerous other forum posts cant resolve it. I cant and wont be going down any garage route as car is not legal yet.

Pump was shagged- seized and replaced. (Amazingly got another from a jag at breakers )
There is 12V at terminal but pump wont work. Measured PD across a load (small bulb) and 0V.
Wipers do work but intermittently in that sometimes they work (any speed) some times don't. All fuses ok, but fuse list says, washer fuse is electronic???
Could it be this sam again !
Now I haven't asked this on forums yet as I dont really need telling the obvious (no offense meant) that I need to plug star in. I dont have one.
I would like information on sam and the circuit perhaps a bit more than a basic or wis schematic if any available. I'm hoping this 'electronic' fuse is just a transistor latch / hold circuit that needs reset (remade), and can be done with out star or another way.
All other functions seem to work, except radio. I'm also suspicious of headlamp height adjust not working but only had both lamps in for a short while so couldn't really test properly.
Advice greatly appreciated.

When two different types of washer soap are used, in the windscreen water tank, they form a gel that settles at the bottom of the tank and is then ingested into the pump and causes it to burn out through effort.

Alternately, you may have a high resistance value in one of the appliances which causes the front sam to burn out by overheating.

Finally, you may be disconnecting the battery to reset faults or jump starting the wrong way, in which case the front sam is blown.

If people replace the front sam but do not find out why it blew, it will just keep on being destroyed.

Hi, thank you for your reply.
I asked if there's any technical information / circuit diagrams on the sam's besides the standard forum reply "if it's blown replace it".

I already said the pump was the problem. It was jammed and is now replaced. I guess your right about the scum in the pump. But they are only titchy washer pumps. If you look at the motor, you will see they are smaller than in any in your kids toys.

The fuse list describes the 'fuse' (= circuit protection device) as electronic. I would sincerely hope the designers have better intelligence than to supply a circuit without one. And then something slightly less trivial than the complete supply board. Or did they consider the sam a replaceable part. It would seem so as anyone who doesn't understand something just replaces it with a new one. Sadly that's why our TV industry died (and many others ) People just cant be bothered.

Oh well, I guess I'll try the forums then.

Hi

The SAMs measure current and if too high just turn off the outputs and log a fault (which of course you can only see with Star ..) they also measure resistance and won't power up the output at all in some cases. Thus its not actually a fuse in the way that a fuse is normally thought of.

(Try removing a bulb and then measuring voltage, you don't get the 12v output at all)

Miro was telling you not to replace it until you really know why it broke (unlike, as you pointed out, many of the others including many MB dealers who will just replace it where it will function just until the vehicle is out of warranty...)

- Theres an awful lot of similar stuff in the SAMs, and yes, MB seem to think its a easily replaceable part

I've never seen a circuit diagram of the SAM - but if you can find a chap called 'television' (he is a user on here and some other MB boards) I once sent him a SAM to disect so he may be able to give you more info.

Richard

No person here has the right to republish the images or wants to be responsible for typing it out and making a mistake.

The SAM is a computer not a fuse box. Therefore it needs another computer to resolve the issue.

I did not get a reply on how the battery was treated and whether or not it was being disconnected.