My Bronco has never had any leaks into the cabin, but after a couple of days of sitting parked in steady rain I got water inside, it seemed to be starting at the rear edge of the passenger side door, that's where the carpet was wet, and it filled up that little "trough" that is under the door sill trim.

I have seen quite a few threads about this but never read the answer (I had no leak). But there seemed to be a common answer to the problem.

I think that the door drip rail needs to be re-sealed maybe? It does not seem to be cracked. But that seems to be the only place where water would get in there, and it was not raining hard enough to see the water coming in.

 

Sounds like classic rain gutter crack leakage to me. Pesky little cracks at the ends of the gutters let all sorts of moisture inside even if the crack is still small.

 

I have not looked closely for any cracks there, but I am going to reseal it tomorrow. I hope that gets it - before I finish wiring up the new stereo system, I was going to run my power wires to the two amps there.

 

I agree with greystreak. I used urethane glue to seal mine. No leaks since.