1972 - No Hi Speed Fan

All other speeds work. Any one have any suggestions on how to resolve this? I am trying to track down a wiring diagram so any tips on that would also be helpful.

Most likely in the switch or relay (resistor) not in the wiring.

I know the blower works as I ran power directly to the hi pin and it turned on. Now that I know the color of the wire, I plan to test the switch next.