Humminbird 998c/MinnKota Terrova Sonar Interference

998c installed on bow with a Terrova IPilot with US2.
The sonar function works fine if the remote is on with a speed setting of 0 or 10 or rabbit.
The sonar completely blanks out with a yellow color screen if any of the other variable speed settings are selected.
I installed a MinnKota frequency choke as recommended by the service department at MinnKota but it did not fix the problem.
There are no other items powered off the trolling motor batteries.
I have also tried another remote control with the same results.
We run a 998c on the console as well with a transom mounted transducer with no issues. I have also turned that unit off thinking that if may somehow be throwing some interference but the results are the same.
Something is causing an interruption in the signal.
Has anyone experienced this or have any ideas?
Frustrating to say the least.
Thanks Specseeker

Electronics should never be powered off the TM batteries.

Hi Bill
The locators are not on the trolling motor batteries. The only thing on those batteries is the trolling motor.
Sorry for the confusion.

Read this...Humminbird: America

Then call HB 1-800-633-1468

Rickie

I had the same problem with my 998c on the trolling motor i ended up running a ground fron the skeg to the groung on the power wire this cleared it up instanly can set the noise levels to off and no interference now hope this helps

Spec Chaser were you able to run the ground from the skeg up the shaft with the si/di transducer cable. Hope there's room. I'm going to move my 1198 up front. Thanks for any input on this. Sorry for jumping this thread.

yes

Make sure your US2 fuse ain't blown. Don't look at it, meter it.

Any setting greater than 0 or less than 10 is PWM.

Did you find a solution yet?

Hi All. This may sound crazy but after trying every suggestion and on this site and advice from others we were about to give up when we sat down and reviewed every step taken and it led us to the solution. As I shared with you we have converted our electronics from Lowrance to Humminbird so the locators were new. Our Terrova is 6 years old and had the I-Pilot upgrade installed when it became available. We had checked all of the electrical connections except in the head of the Terrova. Wouldn't you know one of the connections had developed some corrosion. We all looked at each other, cleaned the connection, sprayed some silicone protection on the connection, took it to the water AND IT WORKS PERFECT! Unbelievable!! It was just a matter of crazy timing that it happened right when we were converting the locators as it most likely would have had the same affect on the Lowrance locators. We were never able to retest using the Lowrance locators as we sold them prior to installing the Humminbird's. Normally we would not admit to our stupidity but we thought this might help solve someone else's problem. Thanks for all who shared.