Center High Mount Lamp aka Third Brake Light inoperable

[Duke George V]

Your defrost woes are something I can understand. Some time ago I called in to a local talk radio program that had some mechanics on and hit them with this: the third brake light doesn't work, the defrost switches on when I press the brake pedal, the cruise control doesn't work when the defrost is on. They were unable to offer any advice, instead saying I need an exorcist, not an electrician, because my shit is clearly haunted.

The 3rd light grounding through the tailgate sounds right. Both of my wagons have this same issue, though one doesn't have the cruise issue, and I think I know why. The defrost is painted onto the glass, and gets power from some copper plates glued to the glass on each side. If those plates disappear, you got problems. They go here, right and left:




And power goes through these prongs that touch them:




I think the previous owner of this wagon "solved" the problem by cutting the power supply to the third brake light. I think if those copper plates are replaced, it would cure the issue. It's not that big of a deal for me, since I live in Las Vegas, and it rarely gets cold enough to worry about defrosting the rear glass.