There is nothing in the manual about the system having a backlit keyboard -- so the safest assumption (and in light of noting the absence of a backlight control) is that there is no backlight support.

See the manual here

https://www.dell.com/support/home/en-us/product-support/product/precision-15-3580-laptop/docs

@ejn63​ Hmm. But based on that logic, I would have to assume that there is no support, period. And that isn't the case. This model does have a backlit keyboard available. 

I just purchased it today (Latitude 3389 i5 7th gen with touch) That's why I was searching for its functions, and sadly I found out it does not come with the backlit keyword. While some Dell laptops allow for the installation of a backlit keyboard if it wasn't originally included, the Dell Latitude 3380 does not support this upgrade. There is no BIOS setting for backlight control, and the system does not have the necessary hardware connections for a backlit keyboard. :(  If having a backlit keyboard is essential, you may need to consider an external backlit keyboard or look for another laptop model :( Hope It Helps