I have a 2003 Taurus, why do my dash lights not work?

Third answer the same. Clean off your battery. train a hose on it to wash the corrosion away then wirebrush to establish a good connection. Don't forget the negative teminal, the stud what connects to the frame and to the engine too- get 'em all sparky fresh, turn the key and you will be happy.

don't forget the lug that looks like like a popsicle with a hole in the middle, that one gets caked up too, and probably is responsible for your auxilliary devices misbehaving, as such.

It is certainly a ground problem, and I suspect it may be the ground for the dash lights or instrument cluster.

DID YOU JUMP START THIS CAR LATELY?

bad chassis ground .. or ground socket will cause chassis to seek ground through the parking lights --- push in cig lighter see if it makes turn signal lights in dash brighter ... ah ha ..