90 Quattro 20V L5-2309cc 2.3L DOHC (7A) (1990)
Heated Glass Element: Description and Operation
Circuit Description
Power is supplied to the rear defogger switch via fuse #16 (S16) on the main fuse/relay panel, whenever the ignition switch is in the "On" position.
When the rear defogger is switched on, the rear defogger heat element receives power by way of the rear antenna amplifier. On cars equipped with
electric remote-control mirrors, the rear delogger switch also supplies power to the heating elements in the mirrors.