read this thread
http://67-72chevytrucks.com/vboard/s...d.php?t=522950
Sounds like there are a few options, but if you have 2 speed and the motor is not actuated by a cable, then the dash switch works by grounding to the dash, it grounds one wire for low, the other for high. There is always power to the motor when ignition is on.
you can probably confirm with your broken switch if the remains of the broken off tabs ground to the switch body when you move the switch
so if all this is correct, the two wires you ran to toggle switch from the motor, what happens if you touch one to ground when the ignition is on?