Spend some time looking through this:
http://www.autozone.com/servlet/UiBr...ginRepairGuide If you're good with a meter and wiring diagrams they are there. Not the greatest but they're there.
There is
a chance all three of these could be caused by the Body Control Module (BCM) also known as the "body computer". It's under the dash either in the center console near the floor or near the junction block on the left side. New ones are $3-400 but, there's always the junk yard.