I know the interference issue has been talked about many times before but mine seems to be different this time. Run humminbirds front and rear. The boat had a 24v motorguide and I got interference on the front graph when running the trolling motor. Before I tried any of the suggestions to take care of it, I bought a 36v terrova. No more interference. Traded the 36v for a 24v terrova and took it out for the first time today. I was using the built in US2 transducer and every time that I turned it on, I lost the bottom reading and the screen just filled with interference. Units are linked together so I switched it back to the transom transducer and same thing. Later in the day I was in the back of the boat and found that it was also getting the same issue on 2d,di and si screens. It was running everything off of the rear transducer. I never had the trolling motor effect both units.
Trolling motor has it's own batteries and the cable runs on the left side. FF both wired direct to the cranking battery and the wires run the other side. Units are linked together along with the MK link through a 5 port hub. Is it common for the trolling motor to effect both units? It never has before for me.