deilenberger

Well, we had another round of rain of biblical proportions last night (inches in an hour sort of rain..) so this AM I checked the P!G.
I found the floor wet again. Not as wet as prior wetness, but for sure wet. I pried up the carpet and the foam was again wet, but it appeared my drain had worked, the wet wasn't up as high, and not as much got wet. Spent some quality time with towels wringing out the foam and drying it off again.
So - it appears that heavy rain causes the leak (and perhaps the HVAC contributed..) So I started tearing things apart looking for the source.
I first popped off the fuse cover and the trim next to it on the starboard side, to find:

Hmm.. drips. Then I looked further and saw:

More drips. They're appearing from behind the A-pillar trim piece (at the top of the photo..)
The drips appeared to be travelling down the inside surface of the A-pillar inside trim. The path followed down past the fuse box and behind the right side kickpanel under the dash, right into the foam backing of the carpeting.
I decided to look further upstream.
To do so - I had to remove the A-pillar trim. This is actually rather easy. I had already popped off the little trim piece near the fuse box cover, and I went looking for what holds the A-pillar trim in place. Found it - one long T25 screw under the "AIRBAG" logo on the trim:

After removing this screw, you can easily pull the trim out from the top down - pull it toward the center of the windshield to release some stab-clips on the back, and it then slides up and out from next to the dash.
Quite easy actually (and a good time to tidy up any wiring that had been tucked behind it.) There is a side-curtain airbag there, so use a bit of caution (don't jam screwdrivers willy-nilly in behind it.)
This is what's found once that trim is removed:

You can see the path the drain hose takes. It's quite well protected, and there was no sign of leakage on the outside of the hose, so I suspected that up higher in the hose wasn't a problem (but decided to look anyway.)
I next took the trim piece off the sunvisor mounting and two T20 screws behind it, which allows pulling the headliner corner down a bit. The actual mount stays attached to the headliner and no wiring has to be disconnected.

If I could have figured out how to remove the passenger assist handle in the roof I could have pulled the headliner down even further, but as was, it came down far enough that with a Maglite LED flashlight I could see the hose all the way into the drain fitting for the sunroof drain:

All looked good on the drain hose. No tears, no sign of wetness.
I went up top, opening the sunroof and looking around, and found there was leaf-munge in the drain area and on the tracks of the sunroof mechanism. I used my high-pressure air-gun to clean the crap out (after using my fingers to get the big stuff out - and there was some crap blocking the drain.)
It turns out, if the drain is plugged and enough water gets into the area (I did an experiment with a pitcher of water), it will overflow around the edge of the sunroof, and the headliner happily routes it right down the A pillar trim with the plastic backing of the trim keeping it flowing nicely down past the fusebox and out eventually to soak the floor.
Lesson - clean sunroof drains. I blew them out, then checked again with a pitcher of water, and the water happily ran out the bottom of the truck, and none appeared along the drain line, or dribbling down the headliner.
Here is the rough location of the drain as seen from up top. It's actually almost (not quite, but almost, you'll need a good Maglite to see it) impossible to see due to the wind-dam popup in the sunroof housing.

While I was in the area, I cleaned up the fuzzy edge of the sunroof gasket (it had hardened munge on it) and where it meets the body (which also had hardened munge on it) in the hope that the gasket seals better.
I'm awaiting the next rainstorm (doesn't look like it will be a real long wait - probably tomorrow) to see if this actually helped anything.
Thanks to RFM for suggesting I check the sunroof drain. Biggest trick is getting so you can see it.