Main dipped headlights not working

Hi,

I have read:

The windshield wiper and headlamp circuits had circuit breakers in their switches. The back-up lamps and turn signals took their power from the windshield wiper switch, and thus the windshield wiper breaker. The cigar lighter and interior dome lamp get their power from the headlamp switch and use the headlamp switch circuit breaker.

Found here:

How to fix Plymouth Valiant / Duster/ Dart electrical problems

These issues all seem to be linked, where physically in the car do all of these circuits link up please?