Front meaning closest to the radiator....I think we are saying the same thing.

The one with 4 wires going in is the one that goes to the ACC, and also seems to be the main current supply for the car. The one with two heavier gauge wires must be the starter solenoid switch then?

The smaller, violet wire that connects @ frontmost post and comes from the 4 heavy wire bundle must be to prevent the ACC from engaging while the starter is drawing current?

__________________

Current Mercedes
1979 maple yellow 240D 4-speed

Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT