Welcome to the Humminbird Side Imaging Forums Rwe0659.
Is this a new installation or just a new problem?
How is your 899ci HD Si unit connected to the battery: new wires straight from the unit to the battery or are you using the boat’s wiring?
Is the 899ci HD Si unit wired to the cranking battery or one of the trolling motor batteries?
Go ahead and check all of the electrical connections for any that are loose or corroded. Don’t forget the fuse, fuse holder and battery terminal connections here.