First, the obvious. Make sure you don't have the light switch turned so the dome lights are on.
Next, check the each door switch. They work by grounding when the doors are open so there may be a short. Use a wrench or socket and turn each one about 1/2 turn and close the door. If the lights are still on, remove the switch (careful with the wire). Once you pull the switch clear (breaking the cicuit), the light should go out. If not, try another door.
If you lose the wire off the back of the switch, you'll likely need to pull some panels off to get to it.