2000 Windstar Headlights on all the time

The headlamps on my 2000 Windstar stay on all the time when the switch is in the "autolamp" position. My mechanic says this is a sensor issue which requires removal of the entire dash assembly in order to replace the sensor. This sounds like the classic $30 part/ $500 labor scenario- any ideas from the forum?

I have not checked into this, but I thought the sensor is behind the rear view mirror (ie, facing the windshield)??