Parking lights, rear lights are working, but headlights are not. Could this just be a fuse?

First check your fuses. If ok. Turn your headlight switch and see if rear parking lights turn on. If they do more than likely your headlight switch is not your problem. If running lights dont come on, check your headlight switch operation..

Do the front park lights work? The front and rear park lights should be on the same circuit. If no park lights operational, possible switch or power/ground issue. If only rear park lights not working, suspect burned out bulbs/wiring problem to rear lights

check bulbs and connectors

problem with a wiring plug in the loom somewhere at the back of the vehicle ,quicker to rewire the rear lights from the switch back

These are all different circuits. The brake lights are on a 10amp fuse - the headlights are on a 50amp fuse - and the parking and dash lights are on a 20amp fuse.
Do you have power going into the headlight switch and the brake light switch ?

Since these lights will work auto or manual is there a relay that might be bad. You mean these light's won't work auto or manual ????
Did you check the TAIL LAMP LIC LAMP fuse 15 amp . ?
Located in the right I/P fuse panel open passenger door plastic panel end of the I/P pull ,fuse box behind . This fuse takes care of the thing's your having problems with

Same issue also when the fuse blows i looks my electric seat controls. I found the problem was underneath the hood underneath both the fuse boxes it was a power wire pinched under a plate that holds the fuse boxes on. This wire probably wore through after 140,000 miles of rubbing and being pinched. tell me if it works for you
Vehicle: 2003 impala

sounds more like a bad fuse to me check your fuse box for a blown one

dash and tail sre tied together, so chk tail light fuse.

Sounds like a blown fuse. Have you checked the fuse box for parking light fuse?