Rear Defogger turns off with brakes

My 1990 wagon has a rear window defogger that wasn't working right, and the switch would reset to off each time the brakes were pressed.

I found that the contact pad on the window had become detached. I taped it back on the window (afraid to try to solder it) and it all worked fine after the repair.

However, it always confused me that the brakes could turn of the defogger until yesterday... I noticed that the third brake light is also mounted to the window, and it also used the same return circuit as the defogger. Apparently the voltage applied to the brake light was enough to reset the the defogger timer and turn it off.

The ground connection is suspect when that occurs. I've had the same thing on vehicles with a liftgate glass, where the ground is supposed to connect through the gas spring.

I'm surprised at you Blue.....