When my automatic headlights come on at night, my nav system goes into night mode and dims the screen. I don't know what the set-up is, but try the auto headlights if you haven't.
jc is correct! When the dimmer switch is turned all the way to the right, the Nav screen stays in day mode. If you turn it to the left slightly past the "click" it will allow the NAV screen to go into night mode at night with headlights on.omg, lol i figured this out a while ago, but it took me forever there is a knob near the left console that dims and brightens the overall lights of all the interior buttons as well as the entire dash, but if you turn it clockwise all the way, to full power of light, then it WILL NOT change automatically into night mode, you have to have the knob right before the click, hopefully you know what i am talking about!