Headlights, dash lights and taillights not working

Nope. All of those circuits have their own individual ground wires, and we know they are not all broken. You have to look at what all of those lights have in common, and that is the switch and the twelve volt wire feeding it. The fact that you observed there are numerous non-working circuits works in your favor. Working around the switch is easier than following wires to a bunch of lights.

What kind of help would you like? Do you want to do some voltage testing? If so, you will need test light or digital voltmeter. You will also need to pull the head light switch out so we can take the readings on the wires.

I had to guess that you have a 3.1L engine, then I looked at the wiring diagram, and found there are two different twelve volt feed wires to the head light switch. It is not likely both developed a problem at the same time, so we should go back further to the fuse box. Does your car have fog lights, and if so, do they work?

Look for the 20-amp "tail light" fuse. There will be two tiny holes on top for test points. Check for twelve volts on both sides of that fuse. If you find it is missing on both sides, a good suspect is a corroded connection behind the fuse box. GM experimented with aluminum wire around this time period, and it proved to be a disaster. Two different kinds of metal, and an acid, is a battery, and results in corrosion. The rivets connecting the wires to the fuse holders could be steel or brass, and salt is the acid. The biggest problems came from salt on your feet, but water is also bad news. The clue to this is the lights might start working if you push or wiggle on the fuse box.

Let me know what you find.

If the generator is not recharging the battery, you will still have lights, but they will be dim.

No. Ia m saying you are falsely blaming the generator. It could be bad, but if other stuff works, like the interior lights and radio, the head lights will work too. They just might be dim.

What did you find for voltages on those fuses?