Day - Night Mode

Have you changed the locale setting? Are you using a custom theme?

Maybe try reset GPS? Sometimes updated files my not be read correctly because of cached data for example.

If soft reset won't work backup your data an try reseting to factory defaults.

I will try this and see if there is any change.

Is there a way to reinstall the basic system or is this what a hard reset does?

How do you do a "soft" reset?

I know how to "hard reset" or "restore to factory settings" but I'm not sure what you mean by soft reset.

Switch the unit off rather than just to standby. Hold the power switch down until it asks if you want it to shut down.

Having the same problem on 2 different 3590LMTs. I've done everything but a hard reset. The sunset time is about 2.5 hours later than local sunset time.

Check Time Zone settings

EXACTLY!

Can't set a location for it as it auto sets it so i'm not sure what else to do.

How do you do that??

Try Settings>Units and Times>Current times. Uncheck Automatic and set your time manually. Exit out. Press and hold the off button until Power Off appears, and elect that. Restart and verify the correct Time is showing. Let it stay set that way for a while, then go back and choose Auto and see if the time sticks.

If you are using the automatic time setting, and if you haven't used your GPS for a long time, you have to get a good satellite fix in order to correct the current time. It doesn't sound like that is the problem you are having though

What ended up fixing it was the next map update. Until then, i got good at choosing nay/night mode manually or just living with day mode and dimming the screen at night.

https://support.garmin.com/ms-MY/?faq=5BltbQj0Ff0yOqAXFZ0hlA

Note as well, the comment at the bottom of the page referenced in the link

for my nuvi 3590 that fixes the issue. It may fix your 3490 also.

Wow. Thanks for sharing the fix. The update should be available to nuvi 34xx and 35xx users through Garmin Express.

nuvi 35xx (GCD File) software version 8.50
as of January 7, 2020
Changes made from version 8.30 to 8.50:
Improved software stability.

and

nuvi 34xx (GCD File) software version 8.50
as of January 7, 2020
Changes made from version 8.30 to 8.50:
Improved software stability.

Yeah, I'm just as shocked as you are about the fix.
I called garmin after I checked everything to let them know of the issue.
I got the usual: did you try this?, did you try that?, blah, blah, go stand on your head in the corner and count down from 1000 while pressing this button, blah, blah, we don't have any other complaints about this issue, etc.
Ultimately it ended up with the sentence I knew it would: The model is outdated and we are not updating the software any further. You can buy a newer model.

Although the above reply I made suggests the update should be available to the nuvi 3597, it appears not to be the case. My 3597 states it's up-to-date with software version 5.50. Maybe it's not for the nuvi 35x7 but is meant only for the nuvi 35x0 model and 34x0.

Thanks I'll take a look to see if there is anupgrade for me.

You can check for the latest Garmin software version on specific models in this FAQ: Garmin | Links to Device Software Update Change Logs. Sadly, Garmin no longer seems to publish the change logs on the newest automotive devices.

Did the Hard Reset after many attempts at the suggestions given in this post.

Unit is working fine now! I am sooooooo happy again!

Thanks to all who tried to help and took the time to post here!

This thread is done!