The circuit board has plenty of sealant on both top and bottom surfaces, but the thin edge does not. I would imagine that you could apply some sealant to that surface, but not sure how much help it would be, unless you are applying it to a brand new board.
Also, I should re-emphasize that my experience with my two LED/reflector units does not necessarily reflect everyone elses. I found evidence of corrosion on both circuit boards of my T-Bird. That does not automatically mean that all the lighting problems with those units are caused by corrosion. LED'S do not usually burn out, but that doesn't mean you don't have some other problem as to why they are not all lit, besides corrosion.
Steve - TCCoA member
2003 Crown Vic LX Sport
1995 T-Bird LX 4.6 retired at 247,888 miles
Thanks for the ride !