Now Nuvi says "can't unlock maps"

thanks anyway,,,found the answer:

If your Nüvi or StreetPilot C5xx series keep displaying the maps are locked, you will need to erase a file from the units memory. Connect your GPS system to your computer; go to start then ‘My Computer’, and double click on your device file (mass storage system), there you will see a folder named ‘Garmin’.

In this folder are several different files, look for file named gmapsupp.img. Right hand click on this file and delete as this file is causing the maps to lock.

How this file got in?

I believe this file is created when you load additional ("supplemental") maps to the Nuvi. For example, I loaded some maps from my MetroGuide North America disc (parts of Canada, Alaska, and Hawaii) to my SD card, to supplement the Nuvi 200's internal map of the "lower 48". These reside in a file called gmapsupp.img in the Garmin folder on the card. When the Nuvi is turned on, it finds those maps, along with its internal map. If that file is found, but is corrupt, or otherwise can't be read, you would get the error message. You might get the same message if you loaded maps from a copy of City Navigator that wasn't unlocked for your Nuvi. Since the MetroGuide maps are not locked, I didn't have that problem. (I don't believe the Nuvi will create routes using the MetroGuide maps, although I can load them into my Etrex Venture so that it will. But I thought it would be interesting to have the additional maps available.)

Hi all,

I have trawled many forums and tried editing the gmapprom.unl file to get the right unlock code on my Garmin Nuvi 310. Still, no joy. I dont have the gmapsupp.img so I can't delete it. Some recommended that I use a PC that has never had MapSource on it before and that didnt work either.

Is there anything else I can try?

Cheers.

I tried everything from this forum as well (http://www.gpspassion.com/forumsen/topic.asp?TOPIC_ID=67141)

Out of curiosity, do you know what you did to get it into this condition?

Which map or maps did this Nüvi 310 come with. I'm assuming they're all loaded internally and you don't have an SD card with any more on...

On the Yellow slip that came with the Nüvi 310, it says Unlock Code: followed by 5 groups of 5 characters - 25 characters in all.

Use Notepad or equivalent and enter those 25 characters in \Garmin\GMAPPROM.UNL (without the dashes) it should unlock.

If it doesn't, then something's not as it was supplied from the factory...and we'll have to delve deeper.

If you have registered your unit with Garmin, login to compare your unlock codes by signing into your account at https://my.garmin.com.

Are you sure that was your problem? I put a gmapsupp file on my unit on purpose, (c530) and it works great. The map I put there is the waterways and lights.

With a SD card in, I can choose between 3 different maps, or all of them.

GMAPSUPP.IMG would only be considered a problem file, if it contained a locked map for which no unlock code was available...

Sounds like the gmapprom.unl file is missing or corrupt. That happened to me when I first installed the 2008 map on my nüvi 200.

Had my Nuvi660 replaced thru warranty. Now the map I had on disc would not unlock. Anybody knows a solution? Thanks.

You need to call Garmin and get an unlock code for the replacement unit.

Didn't your replacement unit come with the latest maps already installed? After you register it go to your maps and it will tell you if you can get the latest and greatest map 2010.1. Just got a 750 replacement and that is how mine worked.