From the Pilot's User Guide page 5-10 -- Choosing “CDI”
causes the course deviation indicator to display above the slip/skid ball. Choosing “CDI+GS” causes both the CDI and glideslope indicators to display, with the glideslope indicator displayed next to the roll scale. If the CDI button status displays “Y” or “CDI+GS” and no CDI or glideslope is displayed onscreen, the EFIS-D10A cannot detect your NAV radio or GPS, there is no active course, or there is no NAVSRC chosen on the HSI page.