Bill and Dave,
I'm replying to both of your responses in one message as some of this is relevant to both of your suggestions, and saves repetition.

Bill,
The wiring diagram you sent made things much clearer to me, thanks for that. An important part I missed is that the timer relay is within the switch assembly. Kind of obvious since the business end of the switch is so much longer than similar dash switches, but I spaced out on that.

Now, with a better understanding of how this system is wired, I'm convinced the two issues are unrelated. Yes, the mirror did work in my test yesterday. The level of heat I felt was real, and consistent with the driver's side. This morning, the RHS mirror did not heat. Much less frost today, but enough. And when I got home from my extremely short excursion of dropping the kids off at school, the RHS mirror was ice cold, LHS warm to the touch.

There's a small possibility that I'm mistaken about the rear glass not working. The mirrors obviously clear in about half the time (making that assumption because the timer shuts off in 6mins vs. 12 for rear glass). I didn't warm the car up very much before driving off--only long enough to buckle my 6yo into his car seat, and scrape the windows (including rear, which I did last, but completely). I'm pretty certain the rear isn't working, since you can usually see at least a little progress soon after switching on the defroster, but I'm open to the possibility I was mistaken. As for this morning, I intentionally left some frost around the edges of the glass, but it was warmer, with less frost, and the sun melted it before I noticed if the defroster was working on the remaining frost.

As for my finding voltage? Well I tested at the bullet connectors after removing the tailgate trim. So voltage seems to be present in the tailgate, but obviously not a guarantee it's making its way to the element itself. I think the connection between the wires and the glass must be under the black trim surrounding the inside of the glass. I'll remove that, and test again. I did measure resistance at the element itself. I don't recall if I measured at those bullet connectors, and I didn't unplug them, so I could have been seeing resistance somewhere else in the circuit. Auto electrics aren't a strong suit of mine.





Dave,
Thanks very much for the detailed instructions on the mirror connections, and more. The RHS mirror did not work (along with rear glass) this morning. As above, I'm of the thought that the mirror and rear glass are unrelated issues. I'm further open to the possibility of my "wiggle / reseat" fix from yesterday was a coincidence. It makes far more sense that there's a compromised connection in the mirror, than in the harness behind the dash. I'm going to follow your advice next. I want to say I probably won't get to this until next week, but I have a feeling I'll pop out for a look this afternoon anyway.