Garmin GNS 480 Installation Manaul page 41

Installation Procedures
2.5.9 Installations with No VHF Navigator (No NAV Antenna)
Installations using the GNS 480 as a GPS navigator only must connect the external CDI to the AUX CDI
outputs, and configure the CDI key on the GNS 480 to be disabled. The CDI key is used to toggle the
MAIN CDI outputs between GPS and VHF Navigation guidance on the external CDI. Disabling this key
will fix the MAIN CDI output to VHF Navigation guidance. This will prevent flagging of the CDI when
the inoperative VHF navigator is selected. The AUX CDI output is dedicated to GPS guidance
information and is the appropriate connection for the external CDI.
2.5.10 Installations with No External CDI
Installations not using an external CDI must be placarded "GPS LIMITED TO VFR USE ONLY". The
external CDI provides the resolver input required for proper VOR Navigation. Without a resolver input,
the GNS 480 will flag VHF navigation functions. It is recommended that the CDI button be disabled if no
external CDI is connected.
GNS 480 (CNX80) Installation Manual 560-0982-01 Rev L 2-9