Adding grounding wire to reduce sonar clutter?

I was explaining my unresolved screen clutter issues with my Lowrance Elite-4 HDI to a Lowrance prostaff representative who was at BassPro today. He suggested I install a ground wire (or did he say ground filter?) on the sonar ground lead.

I thought I understood but am now confused and probably misrepresenting what he said. I checked the Lowrance website but didn't see anything helpful.

Does anybody know what he was suggesting and can clarify what I should try? This is in a plastic hull boat with just a trolling motor in the water. It's a small boat so the trolling motor and Lowrance unit share the same battery. I don't notice a difference whether the trolling motor is running or not, so not convinced this is needed, but thought I'd try it anyway. Should I simply run a wire from the shared battery ground terminal to the metal on the trolling motor?

If you are getting clutter when the TM is idle you have an issue other than TM interference. I 've gotten interference from my TM even with separate batteries so they are sensitive to minor interference. But you should be able to dial in a sharp screen when nothing else is running. I have a small skiff I'm setting up and I plan to use on of the small sealed 12 volt batteries for my DF. They dont weIgh much and are compact.
The main battery will crank the outboard(9.9hp) and run the TM.

If the xducer is attached to the TM, the interference may be encroaching thru the xducer or xducer cable ...

This can be verified by removing the xducer from the TM and test it in the water far away from the TM ...

If the interference goes away - the interference is encroaching thru the xducer or xducer cable ...
If the interference is still present - the interference is encroaching thru the Sonar power somewhere ...

There are steps to eliminate these types of interference "after" the encroachment path is determined ...

Rickie