Problems with steering wheel heating

Hello to all friends of the A8er,

I have minor problems with my steering wheel heater, constantly on. The switch from the seat heating is off and also works. The only way to switch off the steering wheel heater is to pull the fuse.
According to the schematic, there is somewhere such a kind of transistor that switches on the seat heating. Where can I find it????

Thank you and greetings from Kentucky