First time post here. My 2004 K12 auto has no sidelights, headlights, taillights or wipers (although the washer pump works). Do they share a common earth ? Brake lights and indicators are fine.
When I first noticed on mine I used some cotton q tips and removed as much as I could with isopropyl.
If you really want to clear it the best thing might be contact cleaner rather than wd40 this is specifically for circuits ect tho they will both remove corrosion.
The fuses are encased behind a plastic window perfect for condensation to form inside this is the reason why the corrosion forms but it does protect and keep it dry.
You have to open the window to access and so the terminal is best if you removed.
Corrosion in these areas are a worst nightmare for electronics.
Something I really dislike to see but the wd40 can work and I have seen this to be used on circuit boards so is as safe as the contact cleaner.
Mine looked like this before I removed the corrosion it was not that bad but I didn't like to see it.
I wouldn't bother trying the solder method for obvious reasons.
Bad design by Nissan.
I would like to replace the top cover but have not found one as mine kinda just split off the first time I removed it must have been brittle.
Still looking if you see one let me know thanks