61MY Bilge Switch

At my Pilot House helm I have the 4 traditional Bilge switches for FWD, AFT, Port and Starboard bilges. I also have a single switch directly behind the wheel and to the right labeled “Bilge Pump”. I can’t seem to locate what it controls. It has power and illuminates when I place in manual or auto, but I have not located an additional pump anywhere. Our neighbor has a CPMY and his controls his Lazarett pump but we of course don’t have one.Could this possibly be a factory install for an additional pump for future install?Sorry for the sideways pic…

I work on a modified 65. Now a Liquordale 74.
There is a bilge pump that was added under the front of the port engine. Inches ahead of the AC raw water pumps.
Plus the two pumps in the added on cockpit.