It’s actually a fairly common problem among many Ford Ranger trucks! But thankfully, turning the dome light off on your 2000 Ranger is a pretty easy fix.
All you have to do is grab your WD-40, petroleum jelly, or whatever car lubricant you have on hand and apply it to the whole latch assembly on your door. This should help to make your door hinge lubricated enough so that your Ranger’s sensors will “sense” that your door is closed—which will turn off your dome light when you exit your vehicle.