I have seen a lot of questions about disabling or adjusting the Dell lighted keyboard. I have a latitude 5404. To adjust the setting of the lighted keyboard:
1. Restart your computer while holding down the shift key. When the computer restarts into the settings screen, press Troubleshoot > Advanced Options > UEFI Firmware Settings > Restart > after restart, press System Configuration > Keyboard backlight timeout on AC or Keyboard backlight timeout on battery, depending which configuration you want to change and then press your option at top of screen.
Note: I am using Window 10 on my Dell. Hope this helps a few with keyboard lighting issues.