I was kinda worried about that, too, but none of the three depth finder units that have been on the boat & wired into the TM wiring have experienced any such interference. Trolling motor is a Motor Guide & all three units wired into it have been Lowrance (FWIW). Maybe I'm just lucky :dono ... but, yeah I have heard about elec. interference caused by TM & even other units putting out the same signal strength (mHz same on both units).

