Hi All
I've a 1490T I followed the following procedure

Quick guide fo convert Nuvi 1490 US to Nuvi 1490 TH

1. Delete Gupdate.gcd from your Nuvi 1490 US.
2. Backup your GPX.
3. Copy th_TH.kbd , th_TH.glx and 006-D2225-00.bin to their folder.
4. Downgrade your FW Nuvi 1490 US to 3.00 US by 1490 300US.rgn with Updater.
or nuvi13xxand14xxseries_regionfileonly__300.gcd.
5. Convert your Nuvi 1490 US to Nuvi 1490 TH by 1490 3.00 US TO 1490 3.00 TH.rgn with Updater.
6. Reboot and checksum your Nuvi 1490US it will be 1490TH FW 3.00.
7. Your Nuvi 1490 is not permanent firmware you can not update directly by original TH firmware
but it work for JCV and Lane assist.

My questions/problem
1. except for step 4 & 5 which i drag the .gcd & .rgn to "webupdater" it seems to update but when i power off/on the unit the software version is still 4.90 (the downgrade & conversion is not successful right ?)
2. i then delete the gmapprom.img that came with the unit and replace it with gmappromTH110.img renamed to gmapprom.img is this step ok
3. i copied JCV110TH.jcv on to the unit
4. When i turn on the unit it able to display the map manage to simulate route but when it reaches the junction it just shutdown, is the jcv not compatiable?
5. Next i tried play around with the icon, i think the last one that i play with was ecoroute then i turn it off, this morning when turn on the unit it just start up for short while (it didn't reach the gui screen) it shutdown, how should i solve this issue ? Note: I managed to get the updater.exe should i redo the 7 steps again
6. For step 6 how could i check the checksum

Thank you