Whenever it rains I always find a little damp spot near the tail light (mostly on the passenger side). I wasn't sure where it was coming from exactly but the last couple of rainy days we had I noticed droplets coming from the tail light cover and calcium deposits on the nuts and around the tail light housing.
So I finally ordered and replaced my tail light gaskets before the next rain comes in later today so I thought I'd post a DIY article, hopefully this can help someone if they're also having a water leak in the trunk. Feel free to add anything I may have missed or something that would make it easier.
8mm Socket (best if its 1/4" drive)
Small flat blade screw driver (optional)
2 Tail Light Gaskets [Honda Part Number 33503-SP0-A01]
I paid about 32 dollars for each gasket at Thomas Acura in Covina CA.
A tube of RTV Silicon. This will work as well but will make it harder to remove the tail light if you ever need to again.
Approx 30 - 45 minutes per tail light
First remove the tail light cover from the inside of your trunk by unscrewing the little knob at the base
Disconnect the wiring harness thats zip tied to the car
Once you remove the cover you will see 5 screws (6 total because 1 is hidden under the carpet) Use the 8mm socket with the extention to get the 5 visible nuts off. The 6th one is a bit harder because the carpet is covering it. I just removed the extention from the socket and lifted the carpet with one hand and loosened the nut with the ratchet and removed it by hand. Becareful not to drop the nut because it's very hard to find it.
This is the hidden nut located under the carpet
Once you remove all 6 nuts, gently press the tail light from the back and it will come off. Have your other hand in the front of the tail light so it doesn't fly off and break or scratch your bumper. Once you remove your tail light the gasket will probably be stuck to the car like this
Peel off the gasket and it should look like this after
You can leave it dirty like this or you can take a moment to clean it up. I just filled a spray bottle with distilled water and a cap full of car wash shampoo. Sprayed the area and wiped it clean with a microfiber towel. There will be spots where there is rubber from the gasket stuck to the metal so try and remove as much of it as you can. Most of it should come off by rubbing it with water and a towel.
Take the tail light and look at each of the studs and you will see pieces of dried up rubber stuck. Use the small flat blade screw driver to scrape off the rubber. If you don't have a small enough screw driver a pin or paper clip will work.
Since you already have your tail lights off the car you may want to clean them up a bit. Mine were looking pretty dirty so I wiped them down and treated the rubber parts with some silicon spray.
Line up your gasket over the tail light and press the studs through the holes in the gasket.
Reinstall the tail light and tighten up the nuts in an opposite fashion like you would your tire lugs so you don't compress the gasket in an uneven manner.
Plug in the tail light wire harness and put the tail light cover back on and you're done.