Incorrect time on nüvi 255W

**Butters** · 3rd October 2019, 12:03 AM

@Magnetron
I'm 100% certain that he knows how to 'band-aid' fix this problem, i.e. turn off automatic time in settings so that the device isn't getting Satellite time signals as "GPS" atomic time (presently UTC plus 18 seconds) which the device's internal algorithms then convert to local time as determined by it's satellite fix and in reference to it's loaded gmaptz.img map (he has the latest, V22). A manual adjustment of the local time by one hour 'fixes' it but that doesn't alter the fact that the device seems not to be accounting for daylight saving time in his location thus giving the one hour error. It's highly likely due to some minor but persistent corruption in the nonvol region 41. Erasing the region entirely will conclusively prove that's the problem if the time then shows correctly on 'automatic' however there is far more important information stored in rgn41 and it's not known how to remove only minor corruption from a dumped region 41 BIN file and then flash it back. However, it may be possible to force a deletion of non-essential non-volatile information (an action called "Clear Nonvol" and available only in devices later than his 10+ year old nuvi 255W) by doing a risky downgrade of firmware to a much lower version.

@SF
No luck yet finding the old versions. Have you tried erasing 41 yet? If it works i'll redouble my efforts to find them.

**SanFrancisco** · 6th October 2019, 12:27 PM

Sorry for the delay in response, but these are the new findings:

- Created a backup of rgn.41.
- Wiped rgn.41.
- The nüvi 255W is now recognized as a nüvi 2W instead of a nüvi 255W (at the bottom of the splash screen, as well as by WebUpdater and GarminExpress).
- At first boot, got presented the screen calibration process.
- Also had to set the default locale for the device.
- After all that, the local time is (unfortunately) still 1 hour early.
- Due to no fix, restored rgn.41.

I wonder if wiping the drive and starting from scratch would make any difference at all.

**Butters** · 6th October 2019, 11:45 PM

Well that sucks. Downgrading fw won't have any better effect than wiping 41. You could try to reformat it then re-load 'clean' files and see what happens but i suspect nothing will change.

Before you do reformat, if you haven't already tried this it might be worth replacing gmaptz.map just in case there is some tiny glitch in the Version 22 you presently have loaded.

**SanFrancisco** · 7th October 2019, 09:59 AM

Originally Posted by Butters

...if you haven't already tried this it might be worth replacing gmaptz.map just in case there is some tiny glitch in the Version 22 you presently have loaded.

Yes, already tried:
- Took the copy of gmaptz.img off one of the nüvi 250W devices (on which it works fine). No luck.
- Downloaded a fresh copy off the Garmin servers. Still no joy.
- Deleted and copied gmaptz.img from various other devices to the device. No fix.

Next weekend may try a reformat and report back.

**Butters** · 7th October 2019, 10:21 AM

Mysterious and weird! Good luck with the reformat ....

**Magnetron** · 7th October 2019, 03:37 PM

Hope all goes well then.

**SanFrancisco** · 15th October 2019, 12:52 AM

Originally Posted by Butters

Good luck with the reformat ....

The reformat went well, but unfortunately it did not fix the offset of the local time. Will see what happens when DLS ends early November.

**zuvicon** · 15th October 2019, 06:36 AM

Thought my nuvi 1100 HWID=1106 had the same issue as time is 1 hr. behind. I believe the issue has to do with the GPS ROLLOVER WEEK NUMBER issue. From the Tools menu, selecting WORLD CLOCK, I see the date shows FEB 29, 2000, with other countries showing MAR 1, 2000. I guessing GARMIN did not resolved the ROLLOVER issue on some MTK models.

**SanFrancisco** · 16th October 2019, 07:58 AM

I believe you hit the nail on the head here... Having set a location in Switzerland (and unchecked Automatic time adjustment), this is what I see:

Spoiler: pic1

On one of the other (non-MTK) nüvi's 255W, I see this:

Spoiler: pic2

When I place a checkmark in front of Automatic time adjustment, the local time of the MTK device goes 1 hour back.
So yes, you are absolutely right! Thank you for solving this mystery. Rep+ given.