Water in rear under back seats

The truck started smelling bad, but i thought that the kids had spilled something. I finally had time to investigate and found the floor was molding in places because of moisture. The metal legs of the seats were wet like it was condensation, and there was moisture in the Jack area. I'm assuming some kind of leak. It couldn't be condensation, could it? I saw where someone mentioned the cargo light leaking. I also saw something about a rear window drain plug getting clogged. Either of those sound plausible? If it's a drain plug, how do I find it?

 

Do you have a sunroof?

 

Besides what was suggested also there should be some drains in the window pocket behind the seat just like the drains in the doors. Make sure they’re not clogged up.

 

It can be condensation if you live in a wet area. Happened to me in another truck. Also had noticed a small amount of moisture getting through the rear window slider. Carpet gets wet and the water seems to go to the seat bolt area. Your seepage may be from somewhere else but the end result is the same. Ended up having to remove the seat, wire brushing the rust and repainting the bolt-down areas.

 

No sunroof. How do I identify the drains?

 

It's definitely leaking in from somewhere, as opposed to being simply condensation. Had a good rain last night and the floors are soaked.

How do I troubleshoot this? Where are the drains I should be checking?

 

Ok, so I pulled all of the back plastic liner out from behind the back seat and then performed the hose test. Turns out it's coming in through the third tail light, as others have suggested.

 

Interestingly, I also just discovered that the cargo light wont work either. I replaced the bulbs while I was caulking it and it still didnt come on. Wondering if the two are related.

 

Ok, so I have caulked the heck out of that back light and it is still leaking in. The water only leaks when I apply it to that area...and when I do, it leaks down both back pillars onto the floor. Any other ideas?

 

I believe there is a gasket for the lense, chalking may be hard to get right, especially if just chalking around perimeter. You may need a new gasket.
Water may be getting thru the screw holes too. Aslo make sure the lense isn't cracked.

 

Yeah, there is a gasket in there. I caulked that too.....and around the perimeter. The rubber washers on the screws looked good, so I didnt caulk them, however.

 

3rd brake light water leak somewhat common on Toyotas..I see it on Tacomas as well..

 

Sounds like its going to be something odd. My gasket was kinked somewhat but wasn't leaking, thankfully.
If not already, remove lense/fixture and inspect both surfaces, roof and fixture. Something is not right. Maybe call a local body shop and inquire

 

My truck leaked through the third brake light at one point.

 

Noticed last time I was washing my truck that water was easily getting into my third brake light...wondering if this is normal for a 3rd gen???

 

This exact thing happened to me on my Tacoma. It’s how I ended up in a tundra. Exact same scenario too. I was mad as hell at my wife thinking she wasn’t cleaning the kids spilled drinks in the back. My bad.

 

Me too. Couldn't find a replacement for the light to cab, so made one from weatherstripping.

 

Ok, so it may or may not have been the cargo light. I caulked that like crazy and still had a leak. I found that the trim around the rear window had a seal starting to go bad that could have contributed, so I caulked that really good. Im not talking about the rubber window seal, but the actual track seal. See photo. Had a good storm roll through last night, and the truck was dry. So, it passed the first test. We will see.

 

I’m having the same issue in the same places of my 2008 Tundra. Was it the rear window seal then so I’ll need to replace that?

 

Sorry for the delay. I didn't get a notification that you had posted. I think I failed to update the post because I was watching to see what it would do. I haven't had any problems with it, so I assume Caulking around that window worked. I remember tearing into it, but can't recall the exact final solution.