I was having trouble with starting my 1980 240D. I tested several things (battery, cables, shifter) and then tested the key switch. I was told by a very helpful person in another forum to "unplug the connector and use an unbent paperclip to jumper the two large diameter red wires - if that makes it crank, replace the electrical portion of the keyswitch."

I was able to get the starter to turn over by this method (but it wouldn't stay cranked - see next paragraph,) so, it looks like I need to replace the electrical portion of the key switch.

But I've created a new problem for myself. When I unplugged the connector, I couldn't tell which leads went to the large diameter red wires since the plug housing covered it all up. So I took the plug apart and the wires just fell out of it. Now I can't tell which wires go where so that I can put it back together. Do anyone know where I can get a wiring diagram for this? I looked in my Haynes manual but that didn't help.

 

Anyone? Bueller?