74 dart wiring questions

I think the wiring schematic will make more sense if you take schematic A, and B look at them together. That helps show were wires go.

Orange is illumination circuit, it feeds panel lamps via adjustable dimmer on light switch.

The light blue, is dark blue. It is IGN1, N, on bulkhead, it has power in "run" on ignition switch.

No idea on pin 4, the arrow means going off to else where, but should have a note. Might be something like oil light, other gauge sender, color might help...