How do I know if I have electrical interference?

Check your unit
Before trying the below suggestions, turn your depth sounder on without using any options or selections to see if the problem may be in the way the depth sounder was set up to operate. Turn all features on Auto and/or set all options to "Restore Defaults" using the Setup Menu tab. If possible, check your depth sounder on a friend’s boat that has the same type of depth sounder and model number. This will indicate whether the problem is with the depth sounder, the installation of any accessories, or with other equipment on your boat. If the depth sounder still has the same problem on your friend’s boat, return it along with a letter explaining the problem in detail. If the depth sounder works correctly on your friend’s boat, proceed with the appropriate suggestions below.

* Check your depth sounder for interference with the boat sitting still, with all electrical equipment and motor(s) off. This will eliminate any possible source of interference. If this corrects the problem, then the depth sounder is receiving electrical interference from your boat equipment.
* To determine the piece of equipment that is interfering with your depth sounder; turn each piece of equipment back on individually, until the problem starts again. When the problem begins again, the last piece of equipment turned on is interfering with the depth sounder. Also try this with your Main Motor and Trolling Motor running at various speeds.

See additional FAQs on Main Motor and Trolling Motor Interference for solutions to these issues.