Let me add to the confusion....I have an Ultrex, Lowrance 12T w/SpotLight Scan transducer which includes DownScan, 360 for Ultrex and Helix 9 Chirp GPS G2N. On initial rig up and lake trip everything was great and no interference. I cut the SpotLight transducer when stowing the Ultrex (I'm not the only nor first person to do this). I replaced the SpotLight transducer with a new out of the box transducer. The Helix is working fine, but now my Lowrance 800kHz DownScan has interference when the Ultrex is spinning, no interference when I am not on the TM. The 455kHz is fine in either case. The Helix and 12T are stacked on the bow. I have another 12T and a LMS-520 at the console which work fine.

Long story short, nothing changed except the transducer. Not sure this information will be of any use, but thought I would share.

I'm not sure if others have covered this or not, but first a question. Is the noise only noticed while running the TM or all the time?

• Make sure your transducer cable is not pinched
• you can run a battery cable from your negative cranking battery to I believe your last TM battery in the series to try to reduce noise
• Don't route your transducer cord down the cord/cable length from the foot control to the TM head, instead run it along the TM bracket, then down the TM shaft. I'll attach a picture later.

Hope this helps!

Thanks guys for all of the advice!! I will double check the transducer cable and see how they routed it on tm. Definitely going to ground the cranking battery to the tm battery with 18g wire! Thanks again guys!!

I have not read all the replies but I have a helix 12 and wired it all by itself to the cranking battery. No interference. But before I did that I got interference.

I have it wired to the cranking battery also

XTM9 WIDE DI 20 T transducer is what you should be using

Look up filtering on DC power lines. I have no solution for you but I think you may have a DC noise issue that very few people would be able to figure out.

I finally got word on what is causing interference on my bow graph. There is a brown wire in the tm head that connects to the foot pedal. Unplugged I get no interference and plugged in I do! I was wondering if anyone on here knew what that wire does. I want to cut and plug it! Please let me know what that brown wire does if anyone can please in lighten me! Thank you

i looked up the wiring schematics for your trolling motor.. the brown wire is fused which goes to a indicator light.. I would just pull the fuse instead of cutting it... its a ground wire, I think it is a shield for leakage to ground.

Or it is the negative for the indicator light.

Well come to find out it was a bad transducer, from what I was told! Said they used another transducer and now is working correctly. Will have to wait another week to go out and test it. Marine dealership tested it in a tub they have there, so we shall see! Hope it is fixed crossing my fingers!

Hope it all is fixed now. I know how bad it sucks trying to correct interference.

Yes it is me too, we shall see!

Thanks to all for the info.