Where is the headlight sensor located on 2003 mercury grand marquis?
on 2003 Mercury Grand Marquis

Sometimes they come on, other times no. Sometimes they just go out while driving.

Asked by for the 2003 Mercury Grand Marquis
Try turning on the manual switch to see if that helps.
sometimes yes and sometimes no
Go out on dim/bright or either way? If either way i suspect headlight switch, if only one or the other i suspect dimmer switch.