Check Illumination
WARNING: This page is about a different car, the 2012 Subaru Outback and 2012 Subaru Legacy. However, it is still accessible from the selected car via links, so may be relevant.
When the light switch is turned ON, make sure that "ON" lights in ILL+ and then the screen becomes dim.
Courtesy of SUBARU OF AMERICA, INC.
ON: Normal.
OFF: Abnormal. Check the signal line connector. If there are no problems, the unit could be faulty.