Nüvi 3790

[Choco]

Hello good afternoon to everyone. I have a nüvi 3790 that I upgraded and screwed up. Of course I didn't backup NV region 41 before updating it. I was able to recover it with Cure-tool but I have lost the usefulness of voice commands. It has also become a 37xx instead of 3790. I have read everything about this topic on the forum, I have done everything I could, but I have not been able to turn my nüvi to 3790 or the voice commands. I have also not been able to transform it into a nüvi 34xx, when the updater connects in preboot mode to flash the 34xx.gcd file, it tells me that they are different HWDI and cannot load it.

Could someone help me recover my nüvi 3790?

It works well, but the truth is that without voice commands it's a pain.

Thanks to everyone beforehand.

Greetings;
Choco

[Neil]

Depends on what you did, as to what should be done to recover that function.

If, as part of recovery using Cure firmware, you subsequently formatted the file system and it then lost Voice Command it might just be lacking some essential files like SRD, ASR & SRX.

If it was a spontaneous loss of function regardless that all files were left in-place then it likely has a severe corruption in the nonvol region due to your updating attempts. My guess is it was that - due to you seeing "37xx" instead of "3790".

So you need to tell us exactly how it happened, i.e. what you did in detail before it needed to be cured, then a course of action can be undertaken. Regardless of the cause, if you haven't already done so please clear the non-volatile memory to see if that changes anything with the loss of model number: [Only registered and activated users can see links. ]

[Choco]

Hello Neil, thank you very much for your response and help.
I tell you:
- I installed an update for my nüvi 3790 from Garmin Express and once it finished successfully, I restarted the nüvi and it did not start, it stayed in a loop, on the Garmin logo screen.

- I read through the forum and applied the Cure, in cure mode with the firmware (37xx_GDCFile_V5.10.gdc). I got the nüvi to connect to the PC in mass storage mode. I then applied the Cure in original mode with the firmware (37xx_GDCFile_V5.10.gdc) and the nüvi booted perfectly.

- From here I began to realize all the things that were not working well or that were no longer available. nüvi 37xx appeared on the home screen instead of nüvi 3790, in utilities\settings\about\ 37xx also appeared and voice commands were no longer in the utilities menu. I also realized that the DEM mapping was not working well, the shadows did not appear. At this point I made a copy of the entire nüvi hard drive on my PC (folders, hidden folders, files...), but I did not make or know how to make the NV backup.

- With the nüvi 37xx running, I started trying cartography from different free sources, since the cartography I had was from 2011, but I didn't find anything that I liked, I finally found the unlocked Garmin City Navigator NTU 2025.10 cartography and the files extras, so I copied it and ran around with it for a while.

- I tried to modify the Sg 34xx firmware along with the original with the RG-tool, crossing regions, creating .rgn files and trying to install them in preboot mode, but the only thing I managed to do was leave the nüvi in a loop.

- I have learned how to copy and write region 41 through the commands copied to an empty sd card.

- Finally, yesterday, I managed, with Catymag's instructions, to transform the nüvi 37xx to 34xx, apply the activation of the extras and load the Garmin logo. During this process it was the only time I deleted non vol memory. The nüvi 34xx works very well, the DEM mapping works well, the 3D and the roadside assistance I don't know, I haven't had the chance to try them yet and I love the user interface. The voice command is not available for any language, (mine is Spanish) I have tried it with all languages and the same message appears (The voice command application is not available for this language). In reference to the GPS of the 34xx, I can tell you that it connects just as fast as with the 37xx, but it is true that the accuracy in meters is not as good, and I don't know why the car jumps, it seems slowed down.


If I could get my nüvi37xx back to 3790 with all its features working it would be fantastic, since for me the nüvi has a lot of sentimental value.
I look forward to your help Neil. Thank you very much for your help.

[Neil]

Then that's confirming my guess that the loss of function is due to the model change from 3790 to 37xx. The device is now performing like the very basic junior model 3700, no ASR etc., so you have the same symptoms as described here: [Only registered and activated users can see links. ].

The best solution if it works is to convert to 3490 in the hope that the device's PCB version doesn't cause accuracy problems and the jumping vehicle symbol, which is exactly what you've found yours does. Therefore you have one of the boards that doesn't play well converting to 3490.

If you convert it back it will not have the inaccuracy and jumping car but will still suffer the function losses consistent with the model change to 37xx. So, after re-converting you could take the (somewhat risky) path of erasing the nonvol memory (ergn,41) which might restore the functionality but make sure you have a good backup of rgn41 after reconverting in case it goes badly. The other thing you could try is converting it back using V4.9 or earlier firmware then applying [Only registered and activated users can see links. ] but that's a guess because i've never tried it on a 37x0 suffering model loss. TuboCCC's patch is reported not to work with V5 or later fw.

[Choco]

Hello Neil, good afternoon. Thanks in advance.
I am clear about converting back into 37xx. Once converted to 37xx, how do I delete the non-volatile memory? From the developer menu?

Thanks again, regards;

Edit:

[Only registered and activated users can see links. ]

Hi Neil again. I'm already clear about deleting non-volatile memory, you left the link here.

I'll do the conversion and try. I'll tell you things as soon as I can.

Regards;

Edit 2

Hi Neil, I tried to convert to 37xx and when updater.ex started loading the firmware it stopped and an error appeared on the PC screen. I haven't taken a screenshot and I can't tell you what it said. Afterwards, updater disconnected the USB connection and my nüvi was left with a black screen. By pressing the power button, I appreciate that I can backlight the screen or turn it off, but I haven't been able to do anything else (I don't connect to the pec, I can't put it in preboot.....)

How sad I am, I don't understand what happened. You can help?

[Neil]

One problem that is often experienced with Garmin devices that have been 'cross-flashed' (converted to a different but similar device) is that there can be device-specific data written to it's nonvol memory. In your case you've experimented with 3790 US/EU to both 3790 SG and 3490 EU/US and now an attempted re-conversion to 3790 US/EU.

As to the use of the word "deleting", i try to avoid using it in regard to nonvol because it might be thought to have two quite separate meanings - i.e. clearing or erasing. "Clearing" (*see below) nonvol both before and after flashing fw helps by removing recently written albeit non-essential data which might conflict with its 'new identity' and be poisonous to it. Some deeply corrupting data if not removed by "clearing" might need to be removed by "erasing" ALL data from the nonvol (#again, fully explained below). That could have possible unintended consequences involving other losses, depending on the state of the device at the time.

If there is some corrupting data remaining following cross-flashing which isn't removed by CLEARING non-vol before and after the flash, it's quite possible the device will be fine ... at least for a while and maybe even forever. However even a few bytes of bad data can potentially cause the device to crash and turn off, freeze, spontaneously reboot, boot-loop, or worse, die completely with no reaction to the power button. So not clearing nonvol might have no consequences, or result in a minor inconvenience, or prove fatal... i.e. a "dead" (as in "never-turn-on-again") device.

It's pretty hard to kill a 37x0, most can be resurrected if they aren't "dead" and yours isn't because the backlight still works. Not being able to see the screen is highly inconvenient because of the way it attains preboot, whereas for most device it's easy being the left-hand top corner is the magic spot. Probably you can still attain preboot if you can work out where the "G" in GARMIN would be if you could see it, and so the pics behind the Spoiler below shows is where it is so break out the ruler:

Spoiler: Images

[Only registered and activated users can see links. ]
Of course you now can't be sure whether it thinks it's a 3790 or a 3490 so a short-cut is to use your left thumb and hope that works:

[Only registered and activated users can see links. ]

Another way we might get it going is via SD card text commands if it can still recognise a media card, but let's see if you can get it into preboot first. You can be sure it's in preboot by following this:

• Try to use a Windows desktop PC for this rather than a laptop and plug a 'known-good' USB cable into a rear USB2 port (no hubs and avoid USB3 or front ports)
• Hold the power button down while in a dark place until you're sure the nuvi's fully OFF (no backlight)
• Load the 37x0 RGN file into Updater.exe and select the Radio Button next to "USB Device" (don't use safe-naming, naming it just off.rgn will do then it won't matter whether the device is presently a 34xx or 37xx or half-converted whatever)
• Place the mouse cursor over Updater's "OK" button
• Hold the device in your left hand with your thumb on the screen, fingers behind to firmly hold the device while you plug the cable into its microUSB port (whiuch will power it back on)
• Watch the window next to "USB Device" and immediately you see it populate either click OK or hit your keyboard's Enter key
• Keep holding the screen firmly until Updater shows a message, hopefully it'll be "success" and the device will now be a 37xx again then we can go further to fix it after you've cleared nonvol again.

*Clearing nonvol is done via the hidden memory onboard as you'll already aware and it simply removes any recently written data from the nonvol region.
#Erasing nonvol is a far more radical and risky procedure which involves removing all data from the region and that relies on the device being able to then successfully re-boot during which it re-writes the (now completely empty) nonvol memory region from scratch. If that goes wrong or doesn't happen the device may either be toast or may not perform as designed ever again. If it goes right you'll have a fully working 3790 again. Erasing is done by using the command "ergn" but it's an absolute last resort tactic so don't try it until we've exhausted all other possibilities.

[Choco]

Hi Neil, thank you very much for your help.
Yesterday, after the nüvi had a black screen, I was so worried and disappointed that I turned it off and on in pre-boot mode from all points of the screen, on the G, above the G, in all corners, in two corners at the same time, etc., until finally, by touching the center of the screen, I put it in pre-boot mode. (the screen showed "-loading-)
With the illusion of what I had achieved, I turned on the PC, put the nüvi in pre-boot again, connected it to the PC and reloaded the nuvi37xx_GCDFile_510.rgn file with update.exe to see if the installation was carried out correctly but no luck, The message appeared again just after completing the first part of the download:

Spoiler: Image

[Only registered and activated users can see links. ]

I plugged the nüvi back into preboot mode to try to install the nuvi34xx_GCDFile_850.rgn file this time and surprisingly it installed correctly and the nüvi booted up again as the nüvi 34xx.

Today I have been testing the nüvi 34xx again and it is perfect, as I told you the other day.

When I got home this afternoon I followed your instructions. I have flashed from 34xx to 37xx and the screen is black again but with lighting. I followed your instructions and finally flashed 37xx, deleting nonvol from the developer menu before and after flashing, I installed the logo for 37xx, deleted nonvol again from the developer menu but no luck. The nüvi is still a 37xx, voice commands do not appear, nor does bluetooth, the maps are activated but 3D (I imagine) and DEM do not work. Tomorrow I will test that the GPS works correctly. I await the next instruction.

Thank you very much for your information and support.

[Neil]

Maybe you'd like to load the 37xx firmware treated with [Only registered and activated users can see links. ]. It's intended to enable all possible features in 3750/3760 so it might do something to your (now) 3700. I've had no experience with it used in an actual 3700 which i think was a regional European-only device, so I don't know what it will do to your device and it's all your risk if you try it. I haven't read that thread for years but i do recall there was conflicting info whether it worked in fw later than V4.90. If you want to try it, the original V4.90 is available here to patch:

Please Login or Register to see the links

Otherwise, you can go straight to erasing region 41 and cross your fingers that works, details about flashing text commands from SD using boot.bin as Ldr.bin are here: [Only registered and activated users can see links. ]. This is the command to use in Garmin\Updater\1101\update.txt:

Please Login or Register to see the links

Backup nonvol with rrgn command first of course.