Re: dome light mystery
The dome light might be the door switch. Its part of the door latch. Spray it with some lubricant (not wd40, it attracts dirt) till it comes out the bottom of the door. Do that to both and see if that fixes it. You never put the year of your truck down. I had 2 97's that did the same thing and it was the GEM module, but I would try the latch, its the cheap easier fix.
01 Edge Ext Cab
4.0 4x4 White
Custom Winch Bumper, 9000lb winch, Custom Skid Plate, Custom Rock Sliders, Off-Road Lights, Explorer: OHC, Auto Dim Mirror, Lighted Vanity Visors, Power Seat Rails and EATC. Other little things I will remember to add later.