I replaced my original Sani-con a couple of years ago with a 600 and ran an 8 gauge power wire to the house batteries. Also used the switch that came with the pump.
I recently had the same situation on my 2009 Dynasty. You will need to find and replace the controller for your 4th zone with a new CC2 #3312020.000 (Amazon $120.00) I found mine attached to the wall behind the TV. Good Luck !