Front fish finder interference from trolling motor

[BassCatBrad]

Hi all, I have had this issue since I bought my PII new in 2018. It never bothered me much and I actually removed the trolling motor transducer since my Helix's are linked. I am a flipper and shallow swimjig fisherman, but now I want to add 360 imaging and fish more offshore stuff. But enough of that, here's the issue, everytime I use the trolling motor the screen on the front graph goes haywire. It will read 900 ft and I lose the screen completely. The second I let off the trolling motor it comes back. It only happens when I have the front transducer connected to the fortrex. When I'm using the ethernet and reading off the back transducer no issues whatsoever. Any thoughts? I tried a suggestion from a buddy, disconnected the battery charger from the starting battery but the interference still happens.

[Redngoo]

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This worked for me. Though instead of drilling the scag on the troller i sanded a spot on the foot of the trolling motor and used the big clamp that holds my ducer. I will add there is a fuse under the top of the minnkota that is known to blow and cause interference. This would be my first check<br>I will add rf interference is a crazy thing. Wat fixes one person might not fix anothers<br> one person ht not fix another's.&nbsp; Ferrite chokes works for some. I done my splice exactly at the spot it shows on the diagram

[Dennis S.]

On my previous boat which had a maxxum pro, I drilled a hole in the skeg and put self tapping screw in, then painted it with liquid electrical tape. The wire from the screw I attached to the negative terminal of my trolling motor receptacle outlet. I also had a short jumper wire from negative terminal on trolling motor battery #1 to the negative terminal of my cranking battery. It eliminated my interference issues. Current boat, I have had no problems (knock on wood).

[Cestratton]

Did you trade the Helix DI skimmer ducer back to HB for the trolling motor transducer? I have the HB DI trolling motor transducer up front ran up the shaft and along my trolling motor mount not the steering cable. My unit is also wired directly to the battery. I rarely get interface but when I do its minimal lines and depth does not change. Also do you manually set your depth range or use auto?one word of advice if you get the HB TM ducer it has isolators or something inside that helps to prevent interface but also look into getting the Transducer Shield and Saver for the front AND the back of the transducer.

[catdude28]

Did you trade the Helix DI skimmer ducer back to HB for the trolling motor transducer? I have the HB DI trolling motor transducer up front ran up the shaft and along my trolling motor mount not the steering cable. My unit is also wired directly to the battery. I rarely get interface but when I do its minimal lines and depth does not change. Also do you manually set your depth range or use auto?one word of advice if you get the HB TM ducer it has isolators or something inside that helps to prevent interface but also look into getting the Transducer Shield and Saver for the front AND the back of the transducer.

Two good points above to start with:
1) Direct wiring of the units to the crank battery. From the factory, the P2 has the graphs wired through the boat's harness
2) The ducer made for the trolling motor has more shielding than the transom mount ducer

As mentioned, there is no one recipe to get rid of interference. Especially important to check the fuse on the brown wire inside the head which represents the factory installed ground wire. Update your software. Ferrite ring (fixed my interference). Keep the power wires from the graph away from the troller cables. A choke can be added (TMC 1)

[Bass Cat Boats]

Brushless motors eliminate interference.

[catdude28]

Brushless motors eliminate interference.

I would expect the next generation Ultrex to be brushless too to keep pace with some of the other new ones.

[Cestratton]

Back to my post, I ran my transducer cables up the shaft and on top of my trolling motor mount instead of zip tied to the steering cable. Some say it does not matter some do, I was not going to take the chance.