JIm,
Here is an edited version of the ['75 - '80] schematic without the windshield defogger option:
Good luck!
p.s.
The two-stage defogger was always standard on Targas with fixed glass rear window, so this schematic may apply to all early cars, too. I have not checked to see if my car has a different switch, or not. I do know that it has the same relay which I disasembled [NOS spare] displayed here:
