W211 E280cdi brake/electric issue breakdown, help please

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Sep 28, 2011
W211 E280cdi, BMW 118d
Hi guys, I've been a member for a while and a long time reader. It's not very often I'm stumped but this car has got me now.
It's a 2005 '55' E280cdi (OM642) 7g tronic etc. Pre facelift. 192k miles
Over the last few weeks I've been tinkering and repairing/replacing parts, Turbo, cleaning EGR and inlet manifolds etc she's a good runner with plenty of life yet. Last Friday, after some seriously heavy rain, the engine wouldn't turn off and all manner of warnings appeared on the dash. I removed the fuse box and all wiring etc and found a row of corrosion above the sam unit seal. I cleaned this all off, re-installed and refitted the fuse box lid properly, the car has run perfectly since. Until an hour ago that is. There appeared a red flashing warning of Brake failure, depress pedal fully, and almost zero brake functionality. I pulled in, disconnected the battery for 30mins, checked there were no fluid leaks or shortage, no fuses blown, moisture in the fuse box area, absolutely nothing visible. Whenever I reconnect the battery the message appears immediately and I cannot move the gear lever from park.
There are some threads suggesting Sam failure, some suggesting it's a failed battery etc. Having seen the condition of my Sam unit just 5 days ago, I'm reluctant to believe it is this and given the cost of a battery for these cars I'm reluctant to buy one as a "let's just see if it works" solution.
Does anyone have any experience with this sort of thing? Solution?
Thanks in advance, Steven.
Could be that the SBC pump has reached its limit, Strange tho you cannot get it out of park.

There is a Small button to the rear of the gear lever you can depress to get the shifter to move. You have to flip the rear centre console cubby hole lid partially as per the handbook and with a pen/screw driver depress the button.
Cheers merc85, I did think about the SBC, but I assumed there would've been a prior warning of "it's nearing its limit, contact your local MB dealer" instead of out and out and immediate failure.
Yes you should get the warning in white 1st, Unless of course the pump has just malfunctioned completely?

Duff aux battery and Main battery could also bring the red light on ive read. But id had thought you may have starting issues if the batteries were that low?

Needs batteries charging and a code read really i think.
Yeah starting issues would alert me to that surely? Anyway, I was able to fit a brand new boot battery at a cost of £144 (good old Halfords trade card) but has made no difference. Looks like I'll need to carry on down the battery road and get an aux battery tomorrow.
Thanks to your hidden gear selector button I managed to drive the car the 2miles home, very gingerly I might add. I was surprised how much braking ability it had when the pedal was fully stood on, it took some effort though.
I'll investigate more and post results here...
Finger's crossed Stevieno12000, At least you can move it about now. :)
Both batteries now changed, both were disconnected overnight and as soon as they were installed the warning lights came back on immediately. But at least I have 2 new batteries eh... I'll re-open the fuse box area and check for any further failure with the Sam unit.

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