I have water leaking into the cab of the vehicle at the rear passenger door.

Cant say!! 2 people needed for testing, one spraying water on that area with a garden hose and the other inside with a good flashlight! (Looking for the leak 'vicinity') then it can be narrowed down from there. There are no absolutes when it comes to water leaks, it must be located under "heavy rain" or simulated conditions! A good place to start with is spraying water around the door seal. Remember rain FALLS on the truck then runs down,, for some funny reason,, so do the same with the water "sprayed like rain" from the hose!..... ........I wonder how a 'smoke machine' would work for this? Maybe someone has tried it and will reply..?.. just a thought.

poss under warranty at dealer,call and see

I have a work Tahoe the door always fills up with hard rains and I found the small holes in the doors corner get clogged I took a paper clip and just cleaned them.