More than likely it is the headlight dimmer switch.All headlight operations go through it once you have turned them on at the switch.
It can be the relay.
The headlights could have bad bulbs or a bad fuse; the two sets of lights are on different circuits.
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
check fuses and connections at the headlights and the switch in the dash, make sure your headlights are good ;-) that's a start...
humm, This is strange because the DRLs (day time running lights) usually function from the same bulb as the headlights, in other words the headlights are always on so people dont forget to turn their lights on at night so if this is the case you have no problem. The only thing that might indicate a problem would be if the dash lights do not come on when the headlights are on, If this is the case then the turn signal switch could be at fault, otherwise I see no problem with the lights. Granted this could be the case or not but based on the question this is the best diagnosis I can provide, Good luck and I hope this helped
Blown fuse or the lights are just blown and need replacing.