This was the second time i've noticed this on this truck in 5 years. We had a nasty rain storm the other day and truck sat in the parking lot overnight during the worst of it. When i got in the next morning there were some wet spots on the carpet under the middle of the dash (the hump area) I rubbed the my fingers on the underside and felt a small drop of water.

This has me concerned a bit that it may cause a short. But the bigger issue is, where is the water coming in?

 

Probably a leaking windshield at the bottom

 

correct on the leaking windshield. It will actually be coming in from the top corner pass. or drivers side. Mine was coming in from drivers top corner running along a-pillar and then into GEM then along lip of lower dash. Get the windshield sealed up before you run into GEM issues like I did.

 

Gem?

 

I had a 2001 SCREW that developed the windshield leak in 2009.My truck smelled slightly musty for years after a heavy rain but could never figure it out,really strange . I didn't see the water until 2009 when it got really bad.It ran down (inside)my A-piller, behind my fuse panel and got my GEM module wet, then went under the carpet padding. I only noticed the water when it came out of the grab handle bolt hole plug.

After a bad rain, I would turn off the truck, remove the key and the AC blower would keep running, my pollution control pump motor would make crazy noises, my compass display would freak out, my airbag door chime would go into failure notification mode etc.

After it dried out all was good. When I replaced my windshield, I could push the top drivers side corner of the windshield and move it about 1/4 of an inch. The installer told me there was only about 16" of adhesive holding my entire windshield in. He pushed it right out .......This and a rust hole in the roof's rain channel were the deciding factors for me trading in on a 2010 Lariat...Get it fixed now before it hits the GEM module!!!

 

WTF is the GEM module?

 

The GEM module is basically a junction block where all sorts of relays and fuses are when it gets wet the water kind of joins all these circuits into one and makes them do all kinds of crazy stuff. speedometer quits windows wont go down unless in neutral (happened to me)