(13-04-2012 07:21am)mark_n Wrote: I'm away from the car but I would have thought that the sensor to switch on the headlights is in the windscreen looking skyward, whence comes our daylight. The sensor for the dash should be in the instruments themselves monitoring incident light on the face of them and adjusting the intensity to aid readability. Go into a tunnel and they dim, come out and they brighten.
As for the auto dip sensor, that's looking ahead from the rear view mirror and I assume it will have a narrow angle of view (but not so narrow that normal adjustment of the mirror will throw it off) to focus just on the road ahead. Quite tough to make it foolproof, I would have thought.
The sensor IN the car is for the instruments, not the headlights. The headlight one is elsewhere, I was speculating actually in it. In the case of the headlights, I am referring to automatic on/off, not automatic dipping (which is obviously yet another sensor). The point I was responding to was that the headlights turn on at 'night' at a slightly different time to the dimming and/or automatic background colour change of the screen, indicating that the job is done by two different sensors.