I can't speak for the T430S but the T430 has 2 levels of backlighting and then if I click function space 1 more time the backlighting goes off and the little la

I can't speak for the T430S but the T430 has 2 levels of backlighting and then if I click function space 1 more time the backlighting goes off and the little lamp at the top of the screen turns on.