Another case of: RTFM !
I just read the 380 S2 manual and the section about the electrical
panel says that the auxilary switch is for "comfort (waste water
pump)". I suppose they are talking about electric
We don't have electric heads so our switch is not connected to anything. I ordered the required Mate-n-Lok pins to add to the connector so we can use this switch for our outside fridge.
I had to order a few Mate-n-Lok pins anyway as I have to fix another connector on the panel: the switch for the steaming lights activates the instrument lights instead!
The steaming lights are wired to the sailing nav lights instead, and from what I can see this was not messed up afterwards but a wiring
mistake by the factory...
The previous owner obviously never figured out that something was wrong - or just did not care at all