pentoman and stevebfl,
While stevebfl may not say I was wrong, I will. If that is a dianostic plug, it is not the unit I was describing. The ingnition timing changing device is about the same size, and has a black cover with a bunch of male pin connectors sticking out the underside that engage a bunch of female sockets in the piece mounted on the fenderwell. It is not intended to have the cover come off, but it will come off if you pull it off. No damage in pulling it all the way off though.
The unit I was talking about is on the driver's side of the car. In the bulk of the world that is on the left side of the car, when seated inside looking forward. With everything on your car on the other side, perhaps this item is over there too.
I only see the adjustable timing unit on autos with factory emissions equipment early in the transition from leaded to unleaded fuel. Does yours require unleaded fuel? Other cars typically use a single resistor somewhere. It is possible your car does not have the adjustable unit, and your resistor is burned out.
I hope I did not screw things up too much with the misidentification of the diagnostic socket. Jim
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)