Is this it?

http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1EQ0PTV2S1JL14YSTK&year=1991&make=MB&model=190-E-005&category=P&part=MAS+Control+Unit


Is called a MAS. Several circuits integrated into it. Before 1990, fuel pump relay, KLIMA(a/c) and other stuff had separate relays. They are all now in this gadget and boy does it hurt your wallet when this baby dies!

__________________
'91 300-SEL