86 126c speaker wiring
 

Putting head unit in my 1986 560SEC. Seperated the + wires in the fader switch. Now I just need to know where the grounds are. This is a common ground system so there must be a solder ball of these speaker grounds I can split and run wires to my new head unit with. Hopefully its the group of brown wires tied up in the bottom of the picture below. Can anyone confirm this?

Brown wires are ground in these cars. You could always run it to a chassis/trim screw or something too if you wanted to add a separate ground (usually a good idea).

earth
 

Im not talking about the ground for the radio. Im talking about the ground side to all the speakers. The positive sides to the speakers run to the fader and the grounds are all grouped together...somewhere...I just need to know where.

You might want to try the audio support!