I had my TL for a few days now and had the display in AUTO Mode. It would get darker at night when I had my headlights on. The AUTO feature seems to have stopped working as of yesterday. I have to manually switch from Day to Night Mode now. If I manually switch it, it does still change. Any ideas ?

 

Check the max bright switch on the dash. If on max bright the navi display won't dim when the headlights go on.

 

yuppers he is correct if you hit the max button when you it went to night mode automatically it will not revert itself back to normal operation. the next time you go into night mode it will stay lit, just hit the max button again with the headlights on and it will return to normal.