Sargent 328 charging issues 2014 nuevo

Problem is when  I switch  on the battery switch 0n the controle panel  to leisure battery is get no charge to leisure  battery this is on solar and hook, up  ,turn off the battery on control panel and then charges as normal  ,any advice  please ,

I  have   noticed  something is  running when the controle panel  turned on  sound's like a very quiet  high speed pump buzz near the truma heater   ,  turn the controle    panel off the noise  stops  , I first noticed the problem  when  I checked the charging  current  to  leisure battery  was  nill ..

The power on/off button activates/deactivates the habitation area 12v electrics.  The battery select button selects either the leisure or vehicle battery to power the habitation 12v electrics, whichever battery is selected receives charge from the mains charger.  The solar controller in the EC328 is dual channel so both leisure and vehicle battery are charged all the time that the solar panel is able to harvest energy.

Do you know what space/water heating system and water pump type that you have?

Been through  all truma settings   all good  thanks   ,going to  remove  all fuses  individually  may Give a  clue  i

Pulled out relays then fuses pulled the toilet fuse , noise stopped gave few wacks with my fist round toilet , sorted ,thanks for replies