T-Mobile has the annoying tenancy to remove the mobile data toggle from the notification panel and the latest GS5 and 4.4.2 is no different. Not a huge issue for those that are on the current T-Mobile plans that allow data roaming internationally, but if you are on one of the older T-Mobile plans that don't allow that, or if you are like me planning to use my unlocked T-Mobile GS5 on another network, having that toggle is handy to avoid pricy data overages.
As per the original thread, the same instructions apply;
1) Download sqlite editor app from the Playstore. (Older free versions force close on 4.4.2)
2) Open the app and give it root permissions. It should populate a list.
3) Scroll and Tap the "Settings Storage"
4) Tap "Settings.db"
5) Tap "System"
6) Scroll down until you find "notification_panel_active_app_list", tap to highlight it. I noticed its a little hard to get it highlighted because it seems to want to highlight the one under it. So you might have to tap the one right above it to get it highlighted. Make sure its the notification_panel_active_app_list, and NOT the notification_panel_default_active_app_list. I picked the wrong one the first time and it didnt work.
7) Once it is highlighted tap the phones menu button.
8) Tap "Edit Record"
9) You'll see a list of all the toggles that are currently enabled to show in notification area.
10) At the bottom of the list add ; and the words MobileData then another ;. So it will look like this at the end. ;AirplaneMode;MobileData; Then press Save.
11) Reboot and you should have a data toggle now. You can now use the edit feature and move it anywhere you want in the list of toggles.
Note: After I edited it and rebooted the "notification_panel_active_app_list" moved closer to the bottom of the list. So if you go back in and dont see it scroll further down