I need an expert cuz I ain't one. I'm steadily getting worse and worse interference on my bow graph from my Trollin motor.
Still got lots of brushes left, no where near worn out
Checked and cleaned all connections
Jacked with the noise filter (doesn't do much)
I've tried both the built in trans on the motor and the clamp on
Even ran my clamp on trans across the garage as far from the Kota as I could. No change

Here's what I haven't done:
Bought a new Trollin motor
Bought a new boat
Installed a choke
Emptied my rain gauge
Set fire to it

My latest experiment came from Doug at the garland bass pro and I did as follows and am quite puzzled.
Ran a ground from the negative side of battery #3 to the negative side of the crankin battery, then ran a ground from the negative wire in the top of the trolling motor to the skeg. Here's my "whoa ax sumbudy"...
I ran the ground as a temporary for experimental purposes, connected at the head and loose and stripped at the lower unit. Turned the graph on to get ready to try it and stuck the ground on the skeg, it kicked the Trollin motor on way super high. Set on 40, blowing wind like it was on 937. Need to know what this is about.

Yes, everything is negative to negative. I've quadruple check that. Seems as tho I've added a battery making it 48 volts but I haven't connected the positive side of anything to anything.

We're dealing with a min Kota 101 maxxum pro and a HB 958c. Bump the trolling motor and go from reading clear as day to solid lines on the screen and 459 foot of water yaddy yaddy yadda.

Of course it's not a huge deal at the moment when you're starring at em but it's driving me crazy. Need hep. Thanks

I ran an extension cord with the plugs cut off to power my graph, from cranking battery.hook the green wire to the negative with the black on the battery; and hooked the green to the trolling motor head and it helped more than anything.

If you have a minkota I think there's a fuse in the top of it.mines a motorguide

I would try just grounding the cranking battery to the trolling motor if that's where your graph gets its power.
Dont do both

are you doing this while the boat is in the water, that's the only way to test. I found this out the hard way. Might be able to just put the transducer in a bucket of to test sometimes it will work but not always. Do you have an on board charger hooked up?

Nope not in the water, just on the trailer at the house. Gunna take it to the lake when the rain quits

Yes there is an on board charger hooked up. Brand new min Kota 315d

I've read that there is a fuse in the motor. Not in mine, it's behind the bow panel. I don't know of that's wrong or bad or don't matter.

Some of the Minn kota motors have spade fuse in the head of it. If it's blown it will cause interference, might try disconnecting the charger from the batteries as well. My trolling will show interference out of water, when in water all is normal. Took me a whole lot of aggravation before I found that out

Bad bad. Bad advice is often free! I've never known of anyone at Bass Pro Shops to be a trolling motor expert - they are typically sales clerks... With a US2 motor, never, make that NEVER connect Ground of the trolling motor to any other ground (such as the boat battery), or any terminal of any battery used for the trolling motor to anything else. If you didn't have a blown ground loop fuse, you do now. You may have also fried something along the way with experiments.

The typical noise interference encountered with electronics isn't coupled via an air gap. This is why a transducer across the room isn't any better. You've provided the perfect path for high frequency motor pulses to get into the graph by connecting the power systems.

First, remove all illegal connections between the trolling motor and anything else. Read the installation/owners manual for the TM. I believe NOT doing this is discussed. Why people are compelled to do exactly what they are told NOT to do is beyond my comprehension.

Second, replace the fuse in the TM. There is a chance you have fried the transducer crystal, in which case you'll need a new one. An on water test with the TM off should tell you this. If you want to keep the transducer intact, don't do any of that Ground connection malarky.

Try a different sonar unit connected at the bow (after you get the wiring correct and replace the Ground loop fuse in the TM) to see if it acts the same. Also disconnect the charger in case there is feedback getting from the TM to the starting battery via the charger circuit board. This could indicate that you have fried the filter circuits in the charger that should be preventing such feedback.

For anyone who may decide to boost an outboard battery by jumping from a TM battery: There are risks with doing so. One of those is to the well-being of the TM, especially if its a US2 model. Always disconnect the TM harness Ground and Positive leads from the TM batteries before attempting such an endeavor. You're on your own with respect to the risks; I just warned of one of them.

Doug at bass pro is not the best person to get advice from. I had the same problem and he told me to hook my graph power and grounds to the trolling motor batteries. I was also looking to replace a garmin with a hummingbird helix 7. I asked him how to dim the display backlight , he messed with it for a minute and told me you could not dim the light. Turns out it can be dimmed. Good luck with your graph. I had to switch from garmin back to lowrance to clear my interference up. Good luck

We had RFI on our bow unit when we hit the trolling motor foot pedal. We tried everything and finally the only thing that worked was a simple ferite ring on the transducer cable removed it.

Each case will be different....