12V factory wiring output

[Laptom]

I own a 230/236 and the current 12V aux button is not used. I'm thinking to use this button to operate the underwater lights with it. Does anybody knows were the output of the 12V wiring goes to? Engine bay (left/right/front/rear), back of fusebox, back of right kickpanel? I know the wires are coming out of the fusebox, but I cannot see them where they are going to.

Thanks.