99 Honda Accord - water in rear taillight - replace housing?

Maintenance/Repairs
1

We have a '99 Honda Accord EX. When it rains hard, water collects in the rear right taillight. We also have an electrical short somewhere - occasionally the lights on the heater/AC controls don’t work, and the heat or AC will be stuck on the last setting we used until the lights come back on again. I finally put the two together the other day, after I realized that we don’t get the short when it has not been raining.

I have three questions -
(1) In order to fix the water in the taillight problem, does that require replacing the entire housing unit, or is there a cheaper fix? O’Reilly quoted me $65.99 for the housing. I will replace it if I have to, but the car is in the shop right now for over $1000 worth of work, and I’m feeling pretty strapped right now :-/
(2) If the housing does need to be replaced, is this something I could do without screwing it up? I used to do my own maintenance, but that was over 20 years ago, and I haven’t even done my own oil changes since then.
(3) Is it possible that the water problem is what is causing the short in the electrical system?

Thanks!

2

It would be better to replace the housing but you can try to seal it. They are a little cheaper at Rockauto but then you have to pay shipping, or you can get one from a junk yard for less. The whole thing should just bolt in from the inside of the trunk so just take the nuts off and the whole thing should come out. You can try to reseal it with a clear silicone bead around the lens. I’d use some blue tape to define the edges then apply the silicone to do a neater job. Unlikely thats the cause of the other problem. More likely there is leak somewhere else allowing water under the dash. Make sure the drain holes for the cowling are open, etc.