Where is my car leaking from?

[zedjr10]

I got a coupe and after it rains or sometimes snows i get electrical shorts it seems somewhere. Usually it is with the abs and get a code 14 i think. Once a code for wheel sensor. Today something different. My brake light on dash would dim depending on how much i pushed on brakes. Would come on half bright. The harder you pushed the brighter it got it seemed. Then this afternoon it stopped. I know i have water leaking into my trunk somehow. I also have the right side of seat in rear turning rust color from this i believe. Have cleaned it before for it to slowly come back. This could be wicking but it got their in first place somehow from a leak. I checked the trunk today and it sort of seems the water gets in trunk from right rear seat. It seems like it overflows and comes back cause i park on a slight hill. The interior doesn't get wet at all. So what seal is leaking you think. Rear quarter panel windows seal maybe or roof runner. I also suspect a leak into an abs switch relay. AM assuming these are same leaks. I doubt this is rear glass leak but who knows. I would see the water more rear ward toward tail lights and i don't. Considering the incline i park on.

[Rilas]

Have someone help you. Get in the car and fold your rear seat down. Then have them spray water on the car with a hose for a bit. You should eventually find water from one of the spots: rear lower window seals, trunk vent, rear tail lights. You could also possibly have a hole somewhere in the rear water drain channel around the trunk seal (this shouldn't happen but who knows with the age of these cars).

You can also take out the rear seats and side panels, then have it sprayed down. That's if your worried about the rear quarter panel window trim.

[Fleetw00d]

The rear lower window seals Rilas mentions are eight clips that hold down the chrome trim at the base of the rear windshield. Each of these clips penetrates the sheet metal and has a gasket that ages/dries out and leaks. The easiest way to determine if these leak is to stick your finger up through the oval slots under the rear window and feel around in that channel. The water leaks into the channel below the window, then flows to the sides (like where the ABS module is) and down into the trunk.