Whats it do?
 

I have a 2000 240TD. There is a on off switch on the back wall of the bathroom very high up. What's it do?

On mine it works IN TANDOM with the light that's located over the shower. By that I mean they are wired in series, which means BOTH switches must be on in order for the light to work. Seems stupid to me but that's how it works.

Thanks that's it!