It's a small Bosch metal box 2.5" x 2.5" x 1" two sets of numbers:
0 285 100 014
and
000 821 0262
I've looked up those numbers here and on google with no real good results...
It's right above the alarm controller on the back side of the plastic in front of the passengers feet.

Onle two wires coming out of it on one connector


I think I want to diconnect it and see if it makes a difference to the engine running or anything working but I only do that if I have some clue of what it is...

I guess I just want to know so I can see if I can use it or need it or not in the future...

__________________
iThink Different
Building an all new electrical system in my
1985 500SEL

http://mb.braingears.com/126_DISC2/program/Chassis/54-345.pdf
This is a section from the factory manual; is describes and locates all electrical relays, control boxes, etc. Hope this helps you.

I do belive I've figured it out...

It's a capacitor that suplements and regulates power to the SRS (ya know, airbags and such)

...disconnected...

thanx yall,
--Darius