Could be from a crack in your sunroof drain tube.

I really doubt taking off the a pillar will show you anything.

1- the rivets are not re-usable.

2- there are three strong metal clips that attach at pillar to the metal body. I have probably broken at least 10 a pillars at this clip point until I finally mastered the art of removal. You need to snake a small pry bar under the each clip(3 per side) and pry up under the clip to remove. I do them 1/2 removed at a time so I pry 6 times total per each side. Honestly, no offense, but I doubt that you will get the first one off without breaking it.

AB has a video on how to install new ones, this should give you some insight into how it goes together.

Good luck.

 

If it was the sunroof drain tube, wouldn't that also make the headliner wet?
Does the sunroof drain tube run down the A-pillar? I could see water visibly running down around the wire loom that wires the kick panel access to the door.
Is there a drain at the bottom of the A pillar anywhere?

BTW, got the center piece of the rivets out by drilling a small hole in it and taping a small screw into it and pulling it out. Theoretically I should now be able to reuse the rivets. I doubt a auto parts store would carry the right ones so I had no choice. I was also able to remove the A pillar molding without an incident, but you are correct, it really didn't reveal much.

 

If its the tube at the junction of the drain tray nipple, then yes. Im really not sure as I don't see the tube failing in the "field" section, but its all I can think of.

If you are sure your windshield is not leaking, then it has to be the sunroof or the Door.

I had a windshield replaced and had crazy noise coming from the bottom, I found huge gaps where the mastic/sealant didn't go.

Maybe try a flashlight test around the perimeter from the inside while using cardboard to block the glass and see if another person can see any light coming out?

 

What do you mean by "failing in the "field" section?

Also, still don't see how it could be leaking from the drain tray nipple, but not get the headliner wet. I have the truck pretty much level.

I did see another little leak around the windshield (DAMNIT) and another around the middle of the front of the door seal.

I will add yet more silicon down the sides of the window, but how would I seal the door seal without simply buying a new door seal?

 

I mean that if it is leaking at the drain tray nipple, YES the headliner would get wet.

If somewhere along the length or the "field" the tube had a crack, than you would not have a wet headliner.

Looks like you found it.

 

Just poured half a bottle of Captains Tolley on it! Going to follow that up with about 20 layers of silicon!

To me, it seems that it was designed to let water into the A Pillar. Is there a drain somewhere near the bottom that could be plugged up?