radio w/nav question




I have a Sony XAV-712HD radio in my 08 Corvette with the TOM-TOM navigation unit XA-NV400. The tom-tom plugs into the radio as an add on. Every time I start the radio it goes thru it's start-up procedure and defaults to navigation. Is there any way to not have tom-tom be the start up screen without unplugging the unit and leaving it that way until I need to use it? I would like to have my radio as my default start up screen. Any Help
would be greatly appreciated.


