The breaker shown is 15A, and there is another that is not shown that is 18A, just in the H circuit, for the headlights.
D1 only connects to D2, and only when the knob is turned CCW. You will feel the detent- its for the courtesy lights. To test the 15A breaker you should get continuity from B to A all the time. To test the 18A breaker you should get continuity from B to H with the knob pulled all the way out.
I'm not sure what you mean by : "Also between B and the coil when I pin is pressed against it". You should have resistance between R and I and it should vary as you turn the knob from hi to lo- try different resistance scales. This is the variable resistor for dimming the 8 dash, 1 ash tray, 1 radio, and 2 clock lights.