Tailgate water leak within it

[Ianbarnes]

Evening all
My tailgate when opened today was dripping inside, both sides from between the metal frame and door card. For ages!
Water Getting in somewhere higher I guess.
No rear screen wash or wiper. But conversion fitted window.
3 of the black drain plugs were present, one missing
All removed now and water making its way out.
Checked through holes and prob insulation there.

I was thinking brake light seal but perhaps glass has a leak.

Any instructions on how to diagnose?

Tailgate has door card with carpet
Also up and down sliding blind cartridge.
Thanks.

 

[drinfinity]

My tailgate leaked after I banged the rubber sealing strip on the back of the van a bit too enthusiastically after carpeting. I pulled it back out a little and it sealed fine.

 

[Sasquatch]

Failed seal around the 3rd brake light?