I bought a 2004 Dodge Ram 1500 SLT 4X4 two weeks ago, and it has been raining here hard the past week. Everytime I get in the truck my Passenger Floor is soaked. I don't have a sun roof and the wet floor is only on the passenger side. I took the Cowl off can't seem to find how water is getting in. I see where it seems to be comming in from under the dash on Passenger side. Has anyone else had this problem, and can someone lead me to the fix to this problem..

 

Most people get it on the floor in the back, thinking it's the rear window, but it's almost always the seal around the 3rd brake light.

Once in a while you hear of it being the front, and if it's not a heater core issue (which would show up whether it rains or not) it's usually the door seals. Was more common in the '02s & '03s, but I think they went to better seals early in the '04s, so I'm gonna guess you have a really early '04 build, probably built late in '03.

Check the door seals, you may need to replace them. Dealer is STUPID HIGH, LMC Truck is high, but nowhere near as bad as the dealer.

Could also be a rain channel is clogged and backing up on you, too...

 

It's not the heater core cause it is just plain water, and it only happens when it rains or I wash it. I took the seat out and lifted the carpet and it was only wet on passenger side front floor and a little bit towards the back behind front passenger seat. But I water tested it with my Dad today and I let him set in it while I sprayed water on front windsheild and on the roof by the doors and still could not find the source of the leak yet. I'm stumped at this point. I'm thinking it could be the door seals but How come water is only getting in through the floor part ????????

 

Because it will get inside the door channels, run to the lowest point, pool and seep in at the bottom.

Same basic thing that happens when the 3rd brake light leaks. It gets in behind the light, down to the top of the window, along the sides and down to the bottom of the window and seeps in. A lot of people go nuts with that one too. Seen dealers even replace the hole window and seals only to have the problem happen next time it rains...

 

Mine leaks from the roof somehow and drips out the screw p,ugs on the pillars. Both driver and passenger side. I thing the orriginal owner had the windshield replaced and it it not properly sealed OR it is the rubber in the roofline which is leaking into the headliner and funneling down the pillars.

I have not even looked into this yet, it's the least of my issues

 

Had the same problem. On the passenger side the wind shield has a bracket at the bottom for alignment. This is mounted with a gasket to prevent water from passing through to a vent just behind it. The bracket on the driver side does not have a vent behind it so there is no problem.
Mine was leaking so water went through the vent and down the inside of the fire wall, so my mechanic fixed it and no more leaks.
I also have had windows replaced so it probably happened at that time.