The day/night mode is not affected by the fog lights at all. When the stalk switch is off, only the front DRL are on. When it is in either of the other positions, the interior, front and rear marker lights are on, as well as the fogs if that switch has been left on. If the interior illumination level is set to MAX, then the NAV screen stays in day mode regardless of the position of the stalk switch. This is on my 06 limited BTW.
If you have been driving without turning on the stalk switch at night, which from your description of the use of fog lights it sounds like you may be, then you have been driving without any rear marker lights at night. Very dangerous!
Originally Posted by rpatton
I have an 06 limited and it took me awhile to figure out the day night mode. The headlights are always on but the fog lights are controlled by the light swith on the stalk. If you turn on the fog lights the Nav goes to Night mode. If the fog lights are off it goes to day mode.