Turn signals light on when the brake pedal is pressed- 1969 Dodge Dart

For the best diagrams, use the ones in the back of the electrical section of the shop manual.
@1969383S has made pdf versions of those, with some of the circuits on different layers. Turning the a needed layers off makes it easier to follow the connections. print or redraw what you need. It will make more sense after you physically have to follow the paths.
1969 Plymouth Barracuda wiring diagram (not mine)