My headlights an parking light alwasy stays on why

Your park/ headlights should have power when the key is in the off position. I would look at your headlight switch.

If you pull the 20amp park lamp fuse and the lights stay on, it almost has to be a short inside the headlight switch.
Will the lights go off if you unplug the headlight switch ?

On this model the headlight switch provides ground for the lights.
You have a right and left 15amp fuse for the headlights, not circuit breakers.
The parking lights use 3 different fuses. The headlight switch sends power to the body computer which activates a parking lamp relay.
Those components would need to be tested to verify the problem.

Probably a bad headlight switch. It controls the park lights, if it won't turn them off, you should try a new headlight switch.

Not very clear as what your problem is...
Headlights run off their own fuse, as they require more power to function, parking lights run off a lower current fuse, what dashboard light stays on, the high beams?
Please reword problem.

I THINK if you barely put on the parking brake, just enough to make the lights go off, but not drag, you will be OK. Try it and see if the lights go out when the parking brake is applied.

check the parking lights fuse

there are more wires that you cannot see that are melted that is causing the problem. trace all of your wires, starting with the license plate light, all the way to the headlights

Left of the two headlight buttons for headlights and parking, there is a vertical slider. It's labeled Twilight, meaning twilight sentinel that keeps the headlights on. Move it down and that shortens the on time to about 5 seconds. If you are sittting with the headlights on and want them to go off, push it to the bottom and it turns the lights off immediately. They will turn back on when the car is put into park.

Move the slider to the top and they should stay on for about 5 minutes. BTW if you just leave the headlight switch pushed in (if you're doing it manually) the car turns everything off in about 10 minutes--inside lights, radio, lights, cigarette lighter power (unless you moved the fuse in the underhood fuse block to make them stay on permanently).

You also may not know that if you are driving or sitting and want the headlights off but the parking lights to stay on, push the Parking LIghts button. That turns the headlights off. I didn't find that for a while because our 98 LeSabre didn't have any way to turn off the headlights while cruising through a Christmas display scene in a park where many people turn off the headlights to help the effect of the colored lights. Please Rate My Response! Thanks! //