I have a 90 4 door. The dome light comes on when I open either front door. It doesn't come on when the rear doors are opened. Was that an option that my base model didn't come with? If so, I assume the wiring is likely there, just a matter of getting a couple door switches and plugging them in. It's starting to bug me, as I have to load my daughter into her car seat after dark. Tired of opening the front door, then the back door just to turn the light on. First world problems, I know.

 

I have a 98 SE. No switches on rear doors. Plugs from harness should be there. Mine are. Just a matter of installing them and plugging in. Not 100% on a 1990 but seems as though they would be the same way.