Wanna Update your Garmin GPS175/GNC355/GNX375 Main software v. 3.30 ?

PhilzSkyHdx

PhilzSkyHdx

Member
Joined
Oct 11, 2025
Messages
45
My Garmin: GPS175 Experimental
re: Garmin Main software 3.30 update for GPS175/GNX375 units

I spent over an hour trying to find out how and where to get the download file on the Garmin websites to do this update on my Garmin GPS175 nav. Garmin must enjoy making it difficult to do this? Here's what I did to generate the SD card install file:
(SB install instruction .pdf attached)

(2026) Service Bulletin 26085 Rev A: GPS 175/GNX™ 375/GNC® 355 Main Software Version 3.30 and GNX 375 Transponder Software Version 2.90
Link: (SB General Description)

Where to get the install file: (link below)
The following content is available for registered users:
Manuals
Software
Service & Installation Bulletins
Service Communiques & Letters

support.garmin.com

GPS 175 | Garmin Customer Support

Garmin Support Center is where you will find answers to frequently asked questions and resources to help with all of your Garmin products.
support.garmin.com support.garmin.com

Doc ID: SB26089 RevA (Service Bulletin, Install Instructions)

*Experimental* GPS175/GNC355/GNX375 TSO Software - Main v3.30

then
Downloaded and Installed below file on my Windows PC to generate the install file on a Mini-SD card, then load into your Garmin GPS175/GNC355/GNX375
(remember 32GB max SD card)

(download this file)
GPS 175/GNX™ 375/GNC® 355 TSO Software - Main v3.30, Transponder v2.90 006_b3353_0e_a.zip
(unzip this to generate the actual install files)

ENJOY!
 

Attachments

Last edited:
Wow, I'm glad so many folks benefited from this! lol

Hey, maybe I was right?
 
Last edited:
This is a Dynon forum...not sure what you were expecting....and yes, Garmin bury their update pages. I expect a few to be coming out over the next few weeks with the AXIS release.
 
F18Sailor said:
This is a Dynon forum...not sure what you were expecting....and yes, Garmin bury their update pages. I expect a few to be coming out over the next few weeks with the AXIS release.
Click to expand...
If we are real lucky, some gps175 units might be pulled from some Dynon panels once the Dynon navigator changes from vaporware to shipping.
 
F18Sailor said:
This is a Dynon forum...not sure what you were expecting....and yes, Garmin bury their update pages. I expect a few to be coming out over the next few weeks with the AXIS release.
Click to expand...

F18 Sailor: I'm probably wrong, but I was just assuming there's quite a few people that use Garmin navigation units (mine is GPS175, IFR approved) linked into their Skyview units. I think it's a pretty important update (imo) with the visual approach VNAV update (and other fixes).
 
Last edited:
Presumably it's because Mac only has a 9% market share, so there's relatively few Macs out there to support, compared to PCs. The weird thing is that market share doesn't seem to matter when it comes to mobile apps. Apple devices have only a 32% market share in the mobile market, compared to 69% for Androids. And yet, there are lots of aviation apps that are only written for Apple devices. Go figure.
 
Rhino said:
Presumably it's because Mac only has a 9% market share, so there's relatively few Macs out there to support, compared to PCs. The weird thing is that market share doesn't seem to matter when it comes to mobile apps. Apple devices have only a 32% market share in the mobile market, compared to 69% for Androids. And yet, there are lots of aviation apps that are only written for Apple devices. Go figure.
Click to expand...
yeah, doesn't make a lot of sense for Garmin to not support Apple devices, especially for this system update. I have an Apple iPad in my RV7 so that I can use Foreflight, which can send and receive flight plan data to the GPS 175.
 
Last edited:
PhilzSkyHdx said:
re: Garmin Main software 3.30 update for GPS175/GNX375 units

I spent over an hour trying to find out how and where to get the download file on the Garmin websites to do this update on my Garmin GPS175 nav. Garmin must enjoy making it difficult to do this? Here's what I did to generate the SD card install file:
(SB install instruction .pdf attached)

(2026) Service Bulletin 26085 Rev A: GPS 175/GNX™ 375/GNC® 355 Main Software Version 3.30 and GNX 375 Transponder Software Version 2.90
Link: (SB General Description)

Where to get the install file: (link below)
The following content is available for registered users:
Manuals
Software
Service & Installation Bulletins
Service Communiques & Letters

support.garmin.com

GPS 175 | Garmin Customer Support

Garmin Support Center is where you will find answers to frequently asked questions and resources to help with all of your Garmin products.
support.garmin.com support.garmin.com

Doc ID: SB26089 RevA (Service Bulletin, Install Instructions)

*Experimental* GPS175/GNC355/GNX375 TSO Software - Main v3.30

then
Downloaded and Installed below file on my Windows PC to generate the install file on a Mini-SD card, then load into your Garmin GPS175/GNC355/GNX375
(remember 32GB max SD card)

(download this file)
GPS 175/GNX™ 375/GNC® 355 TSO Software - Main v3.30, Transponder v2.90 006_b3353_0e_a.zip
(unzip this to generate the actual install files)

ENJOY!
Click to expand...
I have a 375 - installed in certified Bo - is there any way to access the software download to update mine without going to dealer? I've attempted to follow your instructions but get stopped short trying to find download file?!?!?

26089 sends me to 'loader card creation' which sends me to 'dealer resource center' - which, of course, i am not.
 
Last edited:
PYoder said:
I have a 375 - installed in certified Bo - is there any way to access the software download to update mine without going to dealer? I've attempted to follow your instructions but get stopped short trying to find download file?!?!?

26089 sends me to 'loader card creation' which sends me to 'dealer resource center' - which, of course, i am not.
Click to expand...
Good question Pyoder. I thought I read that certified units have to be done by an approved Garmin dealer. I suggest giving Garmin a call to confirm that.

Mine: Garmin 175 Experimental
 
Last edited:
PhilzSkyHdx said:
Good question Pyoder. I thought I read that certified units have to be done by an approved Garmin dealer. I suggest giving Garmin a call to confirm that.
Click to expand...
Yes, They advertise that units installed in certified aircraft must be done by a dealer. I'm trying to find a way around that - was not obvious from your post what kind of plane you had.
 
PYoder said:
Yes, They advertise that units installed in certified aircraft must be done by a dealer (or A&P) I'm trying to find a way around that - was not obvious from your post what kind of plane you had.
Click to expand...
Ya I didn't specify that (mine is Experimental) in my original post. thanks
 
Last edited:
PYoder said:
Yes, They advertise that units installed in certified aircraft must be done by a dealer. I'm trying to find a way around that - was not obvious from your post what kind of plane you had.
Click to expand...
The Garmin website just refers to the applicable FAR, implying that the update could be done by A&P/IA. Did you get the dealer requirement in a conversation with Garmin? My GPS is in a C170, and I have no dealer nearby.
 
updated my GPS175 to 3.30 - the procedure was very similar to loading a next cycle of NAV data and just as quick. It is mind boggling that the certified installs require a dealer to be involved. I jumped several releases (the unit had 3.12). made claude research the release logs and summarize the changes.

Going 3.12 → 3.30 you pick up four releases. Here's the cumulative list, from Garmin's service bulletins.


3.20 (SB 22114) — the big one​


New features


  • Fuel data from G500(H)/G600/G700 TXi and GI 275 EIS units usable on the Fuel Planning page
  • RS-232 fuel formats supported for the Fuel Planning page: FADC Format 1, Fuel Format 1, Fuel Format 2 (requires config mode: Setup > Interfaces > RS-232)
  • Crossfill of flight plans between two Garmin navigators — GPS 175, GNC 355, GNX 375, GTN (v6.72), GTN Xi (v20.30) (config mode: Setup > Interfaces > Cross-Side Navigator)
  • GPS 175/GNC 355 can receive ADS-B traffic and weather from a GNX 375 (config mode: Setup > Interfaces > ADS-B SRC)
  • Route waypoint types expanded to include fly-over waypoints; user waypoints expanded to support user airports
  • Transition waypoints now shown in gray text on the flight plan page
  • Holds at the FAF can now be removed
  • Improved internal AHRS attitude (pitch/roll) accuracy sent to a portable device
  • GNX 375: OAT data fields display when an OAT probe is installed

Fixes: spurious "ABORT APPROACH" on LNAV+V approaches; GAMA Label 100 so a GDU 620 can swap CDI GPS↔VOR; GNC 355 COM tuning from G3X Touch (MapMx Format 2 channel spacing).


⚠️ Known limitation introduced here: database sync to TXi (v3.50+) / GI 275 (v2.60+) is no longer supported at 3.20 — databases have to be loaded per unit. Garmin said a later release fixes it.


3.21 (SB 23037)​


  • Option to set CDI scale on the GNC 355
  • Improved flight-plan import from a portable device
  • Fix: some 1090ES ADS-B/ADS-R surface targets erroneously shown as directional (GNX 375)

3.22 (SB 23109)​


  • Fix: daily NOTAM-TFRs only appeared on the first day issued; now shown until FIS-B stops sending them
  • Fix: Bluetooth traffic output to non-Garmin portables cut out at 27+ targets

3.30 (SB 26085 / 26089A)​


New features


  • Support for AXIS Flight Displays
  • Radio control from GTN Xi, TXi and AXIS
  • Smart Alert popups now coordinated between LRUs

Behavior changes


  • A loaded approach or vectors-to-final can be activated even when the active leg goes to a different airport
  • "Activate Approach" relabeled "Activate VTF" or "Activate → waypoint"
  • Internal Bluetooth disabled when an FS 510 or AXIS is present
  • VSR stays at the calculated VCALC value even with a cross-side navigator running VNAV
  • Origin airport added only once at initialization, and only if the flight plan is empty
  • Improved parallel track computation; faster Nearest Airport list reload after criteria change
  • Local time offset range widened to −12:00 / +14:00
  • "Fuel on Board" → "EST Fuel Remaining" when using sensor data
  • Nearest Airport visual-guidance indication changed from "VFR" to "Visual", and "----" when unavailable
  • GNX 375 only: transponder board to v2.90

Fixes: visual-approach vertical guidance capped at 3° (Service Alert 26050); nav-sync master not transferring when the main navigator loses GPS; user-airport data in map data fields; stored flight plan catalog lost during upgrade; AHRS calibration failing with "Up" orientation; mislabeled satellite constellation numbers; Direct-to course lingering after flight plan deletion; hold timer not reverting to the pilot-set value on exit; STAR header now shows the correct transition waypoint identifier.


Three things worth noting for your install​


  1. 3.30 is MANDATORY per Garmin, deadline January 29, 2027 (3.22 and earlier affected). On an experimental RV-9A a TSO service bulletin isn't legally binding, but the visual-approach guidance bug is a real one.
  2. Back up your flight plan catalog before the update. The "stored flight plan catalog lost during upgrade" fix lives in 3.30, so a 3.12 → 3.30 jump may still eat it.
  3. The 3.20 AHRS accuracy improvement and the 3.22 Bluetooth traffic fix both affect what the 175 feeds a tablet — relevant if the 175 is a data source for Garmin Pilot alongside your GDL 50. Pilot's Guide Rev C (190-02488-01) is the applicable revision at 3.30.
 
You must log in or register to reply here.
Back
Top