Problem with courtesy lights

[Plunkett]

I have an 86 Chevy silverado k10. My problem is that I noticed today that the dome light was staying on at all times. I got off work tonight and it was dark outside and the light on the outside of the back of the cab wasn't on. I got in the truck and the dome light and the courtesy light on the floor stayed on whether the door was open or shut. Once I got home and shut the door, the light on the back of the cab came on but this light would go off when the door was open. I pulled the bulb out of the dome light and it turned off that light and the one on the back of the cab. Can someone please point me in the right direction of things to look for. Also, when the doors are open the courtesy lights are real bright but dim once the doors are shut.