I feel kind of stupid even asking this, but how in the hell do I turn the interior lights on manually? All 3 areas do come on when the door is opened, so I know they work. I thought maybe on the light switch by turning all the way to the left was it, but no luck. The little green light does come on when I pull out a little on the switch, maybe that's the auto lights. But yea, sorry to admit, I can't figure this out. I'm sure it's looking me right in the face. I swear, I'm not and idiot when it comes to cars, I built my 89' V8 S10 myself, so I do have a little bit of skills. Lol Thanks for your help.

 

There may be a micro processor in the instrument cluster that is supposed to close the interior lamp relay and turn on the interior lamps. The relay appears to be working since the courtesy lights come on when you open a door.

The headlamp sw is supposed to provide the ground signal to the micro processor and close the lamp relay and turn on the interior lights.
I would strongly suggest that you confirm this with someone that has access to a wiring diagram for your vehicle.
There could be a problem with the instrument cluster. They can be sent out for repair, but before doing anything , I would confirm my explanation before doing anything else.

 

Thanks for the reply, but I'm not sure of how to even switch the interior lights on manually. Is it by turning the headlight switch all the way to the left until the green light comes on?

 

OK so the wiring depends on if you have a sunroof or not. Here is both wiring diagrams, it is controlled by a processor in the SJB which I believe looks at what position the light switch is and what position the doors are in.
Based on the wiring diagrams the overhead light with three positions - Off, On, & Door. I seem to recall there being a little button next to the light that you push to turn it on. Keep in mind there is a dimmer switch to the left of the steering wheel, I wouldnt be surprised if this dimmer switch plays a part into it.