When I'm driving in the rain, the headlights come on automatically once the windshield wipers are turned on (I can't seem to find this in the manual, but it seems to take about 30 seconds). I see the headlamp icon in the instrument panel, but the panel does not dim. Three times now I've been driving home in the rain (with wipers and headlights on) when, after about 20 minutes, the instrument panel dims. Does anyone know why this happens? I suspect it is because the sensor that triggers the headlights to come on when it gets dark enough thinks it's dark enough so dims the panel. I just can't figure out why it takes 20 minutes, as the brightness isn't changing as I drive home.