I had this issue on my 07.5, and I took it to the stealership 4 times. Each time they "fixed" the problem, and each time after a good rain it would happen again. :doh: this truck does not have clearance lights. I got the stearn lecture about cleaning the drains, blah blah blah. I knew that was not the issue, since my rig is a bit of a garage queen. Then one day when a body shop friend of mine was cleaning up a little fender boo boo for me, I asked him to fix it, whatever it took. I was tired of my $50K truck smelling like a wet army tent. He dropped the roof panel, and took the time to fill the spill tray with water and watch it until it leaked. Here is what he found:
The drains on this truck run down the side pillars on both sides. They let out at a point inbetween the two hinges through a rubber drain that is molded to allow water to drain out but not allow road water in. The problem on mine, and I suspect on lots of these, was that rubber drain piece. According to my friend, it looked as if the molding machine that formed the end did not make the slits properly to allow water out. So what happens is when you get a great deal of heavy rain, enough to violate the seal around the sunroof and wind up in the drains, IF it rains long enough to fill up the drain tubes, which are hardly draining if at all, then it over flows the pan and leaks down the a pillar, or in the middle, wherever the lowest point of the pan happens to be on your particular truck. This is why it only shows up after an extensive test. The dealership does a standard drain blow, tests it for a few minutes and calls it good.
Hope this helps.
