According to my wiring diagram, taken from a manual titled Mercedes W124 1985 to 1995, published by Technibooks, and is called an owners workshop manual, sw=black, and ge =yellow. here are the colors listed in the manual...

bl=blue
br=brown
el=ivory
ge=yellow
gn=green
gr=gray
nf=natural
rs=pink
rt=red
sw=black
vi=violet
ws=white


As far as the circuits go, I measured the terminals on the plug going to the radio using a Fluke digital vom. My Nak works fine, although I have absolutely no idea what the other plug with one wire I described earlier does. Mine was a single plug that had 1-5 numbered on the plug, and had a brown wire with a blue tracer on it. Hope some of this helps.

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Ron Miller
1986 300E