I just found mine on 300E. It was located on left side near the fuse box attached to the body.
It is a black box, about the size of a stamp but a little narrower. I has one black wire (fairly heavy gauge going in and out. Inside there is an aluminum "fuse link".
If you don't have any luck I will go out tomorrow evening in the day light and take a picture for you.
Let me know.
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)