Well I finally made the effort to fit new heated wing mirror glasses due to failure of the originals (1997 A4 2.4SE V6)
The new glasses were fitted with thermistors (I think thats what they are) to shut them down at a certain temp as they would otherwise be on all the time.
Boy do they get warm........
I tried fitting the relay into the wiring so that they are active only when the rear screen was on but was unable to locate the power wire to the rear screen. Tell a lie, I located it but it was live all the time.
DJ