Amel Super Maramu 2000

On NIKIMAT, SM2K #289 I have the Mass Circuit and electrolysis protection. When I push toward the right: no light. When I push toward the left: right light goes on. I only found information on the French Owner manual, the English did not had it. It says: All the equipment in contact with water (pump, engine, hoses, transmission, propeller, toilet, back water tank, etc.) are connected together and made a circuit. isolated from the other electric cable, but connected to the zinc anodes on the rudder. This installation (green/yellow cable) is made to protect these equipment against electrolysis. The anodes will break up and not the equipments. A leak detector is in the companionway, it allow to research the electricity leaks on the electric circuit inside the boat (but not on the masts). To use: push the switch toward "Mass +" if the light goes on, it means the mass connected to the positive circuit of the boat. If nothing light push toward "Mass -" if the light goes on, it means the mass is connected to the negative circuit of the boat. If a light goes on, it is important to find the location of the electrical leak and solve it. How do I do that? After a year, 95% in marina, I recently changed the Anode/Zinc on the rudder, which still looked ok. The only new equipment I added is the new battery charger.