Garmin G3X Pilot's Manual page 345

Selected
Navigation
Source
Approach
Softkey
NOTE: To cancel Glideslope (GS) Mode without cancelling LOC Mode, press
the AP NAV Softkey once. Pressing it a second time cancels LOC Mode.
Selecting LOC Mode with GS Mode:
1) EXTERNAL NAVIGATOR: Tune and activate the desired LOC frequency.
2) G3X: Ensure that LOC1 is the selected navigation source (use the CDI
SRC Softkey on the PFD or PFD Page to cycle through external navigation
sources if necessary). The HSI should automatically slew the needle to the
correct course.
190-01115-00 Rev. J
LOC Mode Glideslope Mode
Active Active
ILS Approach
PFD Page (Split-Screen)
Garmin G3X Pilot's Guide
Integrated Autopilot
Glideslope
Indicator
325