Ford Repair: 93 f-150 door sensor, light dimmer, penetrating oil

Question
When I open my drivers side door the dome light doesn't come on, but comes on when passenger door is open.  I can turn dome light on with the light dimmer, I need to know what the sensor is called that knows if your door is open of closed?

Answer
It's a door jamb switch, and is located on the hinge side of the door.  They're inexpensive (under $10) and usually not too hard to replace.  In some cases you can just spray it with penetrating oil and push the switch in and let is "snap" back out a few times to make it work again.  Hope this helps,
Jason