Nuvi 855 Routes? in GPS Posted July 31, 2009 Create the route in MapSource. Connect the GPS unit with the USB cable and allow it to go into USB Mass Storage Mode. Click the "Send to Device" button in MapSource. Wait for the data to send. Disconnect the GPS unit from the computer. Allow it to start back up. Go to User Data on the GPS unit. Import the Route. Yep. That worked! THANKS!!