Q: the back passenger floor gets wet nothing else, what is the cause and what to fix?

Hello. Thank you for writing in. The windows have drain tubes and holes that take trapped water from the windows and doors and channels it where it can drain. These drains can become clogged over time with dirt and debris. Once they become clogged the water overflows, or finds another pathway to drain. You will need to clean them out or have them replaced to stop the leaking. You can try to used a pressure washer, or compressed air to clear the passages. To help locate and possibly replace the drain tubes, you will want to find a diagram or repair manual. Find the clog in the tube or drain holes, or find where the drain may be damaged allowing water to flow where it shouldn’t, and take appropriate action.