check fuses and connections at the headlights and the switch in the dash, make sure your headlights are good ;-) that's a start...
You might have automatic lights. The sensor is on top of the dash on the left side. If you have that there is a switch to turn it off.
The headlights could have bad bulbs or a bad fuse; the two sets of lights are on different circuits.
The lights on your Buick could be out for a number of reasons. It could be blown fuses, faulty wiring, or dead bulbs. Your mechanic would be able to test this.
Did you check the lights? They could be dead!
If your headlights work, but your tail lights don't, your bulbs could be blown. It is possible that you have a shortage in your car.
If parking and tailights are working could be headlight switch--rheostat for dimming control could be bad
It could be a short in the wiring, or a fuse or the headlights themselves might be bad. I hope this helps
it could be the headlight relay. if not it may be in the switch.
If the headlights are not working correctly on a 1990 Corvette, the fuses or lights could be going out. Replace the old fuses and check that all wires connected to the lights are functioning correctly.
The dim lights on a 1994 Grand Prix could go out when the headlamp switch is on if there is a short in the wiring for the headlights. There could also be a problem with the bulbs themselves if they were touched during installation. The oils in the fingers can short out new headlights.
could be bad wiring
There are two reasons. The first is the bulbs in the lamps could be blown or the fuse that run them are blown.