Alan,
Try going to the following menu: EFIS > SETUP > CLUTTER, and look for the softkey with "CDI" over it. The choices to toggle through are CDI Y, CDI N, CDI+GS. Y=yes, N=No, +GS = both CDI and GS. My experience (D-100 in an RV-6) is like others have said, valid course required for CDI to show; and for GS, you have to set the VNAV parameters in the GPS, and when you approach that VNAV profile, the GS appears. For instance, I have my GPS VNAV set at 500 fpm, and when Vertical Speed to Target reaches about 450 fpm, the GS appears, and centers at 500 fpm VS to T. I have my Dynon AP set to fly 500 fpm decents, and it does pretty well keeping the GS centered, depending on winds (it doesn't couple...its a "poor man's VNAV"
but still pretty cool!)
Hope this helps! Here's an excerpt from the D-180 User's Guide that discusses this CDI toggle selection:
"Toggles and configures the display of the CDI and glideslope. 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 FlightDEK-D180 cannot detect your NAV radio or GPS, there is no active course, or there is no NAVSRC chosen on the HSI page."
Cheers,
Bob