Why do GPS signal levels drop when avionics are turned on in my Garmin GNS 480?
If the GPS signal levels drop when you turn on your avionics, it might be due to noise interference from other avionics. To resolve this, turn off all avionics and then turn them on one at a time to find the source of the interference. Additionally, try routing the GPS cable and positioning the GPS antenna away from potential sources of interference.
How to fix very low GPS signal levels on my Garmin GNS 480 GPS?
If your Garmin GPS signal levels are very low, check the GPS antenna installation, connections, and cable routing. Ensure the GPS antenna is mounted on top of the aircraft and free from obstructions like hangars, buildings, or trees. Also, move the GPS antenna away from the COM antenna, add a 1575.42 MHz notch filter in the COM coax, fix or replace the COM, or disconnect the ELT antenna coax to check for possible re-radiation.
How to troubleshoot a Garmin GPS GNS 480 that does not power on?
If your Garmin GPS GNS 480 does not power on, ensure that power is connected to the main 37-pin connector at P1-1 and 16, and ground to P1-2 and 20. Check the circuit, breakers, and main avionics switch.
Why do Garmin GPS signal levels drop when avionics are turned on?
If the GPS signal levels drop when you turn on your avionics, it's likely due to noise interference. Try turning off all avionics and then turning them on one by one to find the source of the interference. Also, route the GPS cable and antenna away from potential interference sources.
Why is message audio or tone not heard on my Garmin GPS GNS 480?
If you can't hear the message audio or tone on your Garmin GPS GNS 480, first increase the AMA volume level, which can be found under the AUDIO menu in the COM function. If that doesn't work, turn the message tone ON via the system configuration page. Also, verify that the inhibit input (P5-77) is not grounded using Ground Maintenance Mode.
What to check if Autopilot is not getting GPSS/Roll Steering data from Garmin GPS GNS 480 (RS232 Roll Steering used)?
If the autopilot is not getting GPSS/Roll Steering data from the Garmin GPS GNS 480 when using RS232 Roll Steering, make sure the output port setting is MAPCOM for the port that the autopilot is connected to, and check the wiring.
What to do if unable to control NAV using VOR bezel key on Garmin GNS 480?
If you're unable to control NAV using the VOR bezel key, make sure power is connected to the nav 37-pin connector P7-1 and ground to P7-2.
How to fix Garmin GNS 480 not receiving baro-correction setting from altimeter?
If the GNS 480 is not receiving baro-correction setting from the altimeter, check baro pot configuration in Ground Maintenance Mode. Calibrate baro pot. Ensure GNS 480 is the only device connected to the altimeter baro pot.
Why Garmin GNS 480 heading differs greatly from compass system (synchro hdg only)?
If the GNS 480 heading differs greatly from the compass system (synchro hdg only), check wiring, synchro X,Y,Z legs are crossed, 26VAC reference Hi and Lo are swapped. Verify that GNS 480 and compass system are using the same 26VAC reference.
Why Garmin GNS 480 is not receiving heading from compass system (synchro heading input used)?
If the GNS 480 is not receiving heading from the compass system (synchro heading input used), check that the heading valid input (P5-57) is > 9 VDC. The state of this input can be checked in Ground Maintenance Mode. Also, check that 26VAC, 400Hz reference is supplied to P5-20,39. Check wiring.
General| Display Type | LCD |
|---|---|
| Interface | RS-232 |
| GPS Receiver | 12-channel |
| Database Storage | Jeppesen database |
| Navigation Capabilities | IFR/VFR, enroute, terminal, approach |
| Approach Types | ILS, VOR, LOC, GPS, WAAS |
| Compatibility | Compatible with most EFIS and autopilot systems |
| Operating Temperature | -20°C to +55°C |
Explains manual organization, scope, and purpose for installers.
Details GNS 480 features, system interfaces, and overall functionality.
Provides detailed electrical, physical, environmental, and performance specifications.
Lists TSO, ETSO, JTSO authorizations, FCC grant, and STC authorization.
Covers database updates, unpacking, and lists all items included in the GNS 480 package.
Lists optional accessories and related documentation for GNS 480 installation.
Specifies license requirements and provides definitions & acronyms.
Guidelines for installation practices, overview, materials, and special tools.
Discusses mounting, wiring, system configuration, environmental factors, and unit mounting.
Explains connectors, interfaces, and functional descriptions of GNS 480 systems.
Provides guidance for installing COM, GPS, and NAV antennas.
Covers weight/balance computation and electrical load analysis requirements.
Verifies mounting/wiring and guides GNS 480 setup and configuration.
Details checkout utilities: Test, Input Monitor, Ground, and Flight Checks.
Ensures database currency, card replacement, and AFMS update.
Provides a guide for diagnosing problems and contacting Garmin for support.
Describes operational limitations, recommendations for IFR use, and system safety.
Covers general installation responsibilities, antenna, equipment interfacing, and licenses.
No calibration needed; mandates periodic VOR accuracy checks and provides cleaning instructions.
Provides guidance on battery replacement and display backlight maintenance.
Lists environmental test categories and refers to STC authorization data.
Details RS-232 serial input and output specifications, including MapCom.
Lists compatible altitude sources and Fuel/Air Data Computers.
Lists compatible heading sources, altimeters, and autopilots.
Lists compatible Electronic HSIs, Traffic Systems, CO Detectors, and Displays.
Diagram showing power and antenna connections for GNS 480.
Diagrams illustrating connections to main and auxiliary CDIs.
Diagrams for baro, synchro heading, RMI, and RS-232 interface connections.
Diagrams for GNS 480 to audio panel and DME tuning connections.
Diagrams for connecting GNS 480 to S-TEC, Century, and Bendix/King autopilots.
Diagrams for single/dual GNS 480 stacks and NAV displays.
Lists suitable CDI/HSI source selection annunciators and vendor contact info.
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