91b16sedan - Good to hear on the swap!! Keep at it and keep us up to date!
Jeff - Sorry I was a big slacker and I forgot to check with my meter. I have a Q for you....have you had any other problems with electrical stuff in the back of your vehicle? My '85 Civic once had ALL the taillights & brakelights stop working. When they put the car together there is a big-ass connector (on my '85 it was between the front and back door under the carpet/door trim, right at about the B pillar) This connector connects the back half of the car's electrical system with the front half...Mine was not making a good connection. I took it apart and sprayed contact cleaner and it helped a lot. I occasionally have my 3rd brake light in my '91 not work and I suspect the same problem..so far opening and slamming the door while my foot is on the brake fixes that!! - lol - also...your switch could still not be getting current to your defroster, even if the light is lighting up. I am sure there is a relay somewhere in the car for the defroster and it could be bad or have a loose wire..etc.etc.. The first test for you is if you have voltage at the defroster itself. Sorry I forgot to check, I'll try to remember tonight.
Later!