W211 - Intermittent Multiple Electric Problems

[Pauljames]

Over last few months on 5 or 6 occasions whilst driving the car exhibits multiple electric faults that include: Speedo & Rev counter stop working, indicators stop working, electric windows & windscreen wipers won't work, engine cooling fans come on full power (I think).

If you stop, switch engine off, then restart - car starts and all is fine.

Been to 3 garages, first fitted new battery - which made no difference, then it went to a Merc main dealer who said it wasn't showing any faults. Then found a Merc Indie who said Star didn't show any faults and suggested a new front SAM unit was possibly the common thread, unfortunately this hasn't fixed the problem.

Its going back to the Indie for another look, but any pointers would be grateful.

 

[DREAMER NO2]

Paul you need to up date your profile with the model and type along with the year of manufacture . W 211 is not enough information for us to help you .

 

[mersum1es]

Check both front and rear SAM if there are signs of moisture/corrosion. You may have some CAN issues too, one place to check are CAN connectors under both front door sills (also may be contaminated by water)

Once again; there is usually lack of voltage to ecu if fan goes at full blast.

 

[DREAMER NO2]

This is a shot in the dark without knowing the year and information other than W211.This may be your sam unit check every fuse in this item first. Return after you do the check.

 

[Blobcat]

I’m guessing early W211 as they could suffer quite badly with electrical issues. Poor earths being one because they put more paint on to counteract the corrosion issues they’d had with the W211. SAM full of water is my thoughts.

 

[DREAMER NO2]

Might be in this location thats the sam in his hand

 

[Uncle Benz]

Might be in this location thats the sam in his hand View attachment 51057

Except that's a left hand drive. Look at picture in a mirror

Sounds like a canbus fault to me

 

[DREAMER NO2]

So the information is not spot on but the parts showing is just for inf

 

[Pauljames]

Thanks for the help, its a 2006 E270 CDI only done 55,000 miles....only other thought is had a problem when the remote key stopped working which turned out to be blowing a fuse......cause was the alarm siren - so disconnected this, put the fuse back in and key worked fine.......never got around to replacing the siren......but don't think this could be related?

 

[Pauljames]

Perhaps not clear from first post - the Indie has replaced the front SAM unit with a new genuine unit from Mercedes, when they dismantled the old one it didn't show any signs of water ingress or obvious signs of faulire.....

 

[Flyinspanner]

Check main earthing straps, check they are tight, corrosion free.

 

[Flyinspanner]

All the items which have had an issue, do they have a shared earth point?
Shared power feed?
I know SAM has been changed, but was the loom to that SAM checked for chaffing, poor connectors?