Problems with backlit keyboard on E4200, #2

Revisiting this once more...

original thread 8/6/19

duplicate thread 5/28/20

As it seems this isn't an issue with the keyboard, but more likely with the ambient sensor under Windows 10. First of all, the E4200 Bios (A24, most recent version) doesn't give me the option to just turn the backlit keyboard ON, I can only turn it off or choose to link it to the ambient sensor.

In Windows 10, the ambient sensor shows up in Device Manager, but when I click on properties/Details, it tells me that device "ACPI\ACPI0008\2&daba3ff&2" actually needs additional installations.

Like I described above, when I turn on the backlit keyboard in ambient mode, it's actually on for 15 seconds, so it's not like the backlight is broken. It just doesn't stay on, no matter how much I type.

Coincidentially, when I link screen brightness to the ambient sensor, it doesn't change, no matter if I put my thumb over it or stick a flashlight to it.

As for the sensor - well, luckily I have a second E4200 so I swapped sensors: same result. Of course, both could be broken, but I don't find that very likely, especially when the Device Manager is already hinting at a missing installation.

So: Driver issue. You wrote that the E4200 was tested with backlit, but was that under Windows 10? Any ideas where to go from here or what to install? All I found was Dell_Ambient-Light-Sensor_A00_R191268.exe from 2013, but supposedly that's only for Windows Vista and (tried it anyway) it doesn't do the trick.

Thanks!