Do all of your units have the latest updates? There was an update a while back specific to the issue you are mentioning. You need to go to Humminbird.com and register all of your units (if you haven't already done so) and download the latest updates for them onto an SD card and then put that SD card with the update specific to that unit in the card reader.
This only applies if you have all three units interlinked of course. If you don't, it's a power issue.
Edited by Bullet20XrD (05/29/16 03:29 PM)