yeah wtf...
My backlight worked just fine until yesterday when I turned it off...now it reacts to ambient light. So thank you all for telling me what I already know about how the light works, but up until yesterday when the "illuminate backlight in low-light condition" box is unchecked...get that, unchecked as in not...then my backlight was manual control just like everything else on my mbp. But now I press the button in the light and i get the dreaded O with / through it...that is usually found on the shower room of most state penitentiaries and stands for "please god don't enter". This is a great misfortune because till now I was loving the manual control backlight...I don't need it I just like it, and damn it sometimes it just feels good to have the reassuring glow. Here is the kicker...I work outside so in the blinding rage of the suns inferno....my keyboard was still manual. So, please god don't reply and tell me that it is an ambient light sensor and needs low light to activate...thank you for your comments, your all really knowledgeable, its just I would like an answer; not a bunch of people regurgitating what they've read on the tech specs page of their local apple.com website. I hadn't turned my keyboard off sense my recent apple update so my suspicion is that they fixed the "bug" and with my restart and turning off of my light I doomed myself to walk the way of the rest...even though the backlight should work the way that it did for me until yesterday. See that way is brilliant, other way...if it is a "fix" then we'll you dropped the ball Steve-O. So please if someone knows if it's a firmware update or something, or why so many of us enjoyed the manual control regardless of lighting...unless we wanted it auto, please tell me. That info would be helpful.😡😕