reporter: the valukas report. an employee who hides or doesn t share information a cover-up? the individual knows, for instance, the information is a safety information and understands that and deliberately decides to conceal that, that s a cover-up, yes. reporter: gm, instead, termed the ignition switch with power brakes air bags all in motion, after coming undone and restarting it. that would be hard for a 16-year-old driver to even think of with an 18-wheeler bearing down on them. reporter: asked how it s changing its culture, barra said 15 managers have been fired and more have been hired. it s a way of changing the way we think at general motors. gm is also being changed by a