Depends if the circuitry inside is fried.

No way for us to tell without a picture.

 

No way for us to tell without a picture.

Even with a picture, you cannot always tell if LED light assemblies are defective visually. They don't 'burn out' as with incandescents.

(The old joke about "If the smoke escapes, it won't work" don't apply.)

Some tail light assemblies would benefit from trying to replace the LEDS but you would need to find the proper ones.

 

From what little I know about the stop light on the newer models, the LEDs are not meant to be changed. The entire unit needs to be replaced. But, before condemning the whole thing, must verify that it is getting powers and grounds. Now, there are some who have managed to replace the LEDs with something else to keep cost down. Personally, I would be trying the same thing if I could. However, not everyone has the necessary skill level to do so.

 

If the illuminators are LED, then the entire unit will have to be replaced. Sure a skilled electronics tech could replace an LED.. IF... IF they could find a replacement (which is unlikely) but you will destroy the seal integrity of the unit in doing so... though with water damage already.. it seems it is already compromised. If the LED is not an exact replacement then it will not match the illumination of other LEDs, and rear light assembly will look a bit "walleyed" in action.

Thing is.. since it was compromised by water, you really need to find the cause and that likely means full unit replacement anyway.

 

This is the part that does not turn on and has water internally. (Crv 2018)

 

You'll likely have to replace that section in the tailgate.

eBay / breakers yard might be a good call if you can find any since dealership prices wont be cheap....

 

I had the same problem with my 2017 EX. Light was replaced under warranty due to water inside then 2 years later the same issue with water penetration's. I found an OEM replacement from Ebay that was removed from another CRV and replaced it my self. You have to remove the back trims plus 6 bolts to get it out. Dealer wanted about $250 for part and labor

 

I had this issue with after market head lamps on a different car. The inside would fog up and droplets would form on the inside of the lens. I waited until we were in a warm/dry weather pattern and then I carefully and thoroughly applied superglue to all of the seams on the light casing. Never had an issue again.

 

Leds are suppose to be long lasting and effective.
However, when replacing a stop light bulb for under $20 dollars versus having to replace the entire assembly for a couple of hundred dollars, I tend to think that Leds weren't such a good idea for automobiles.

 

GMC Yukon brake light only $729 rather than replace $5 bulb.

 

Highway robbery, although with that price it encourages people to create a repair service.

 

LED's will work under water. Water doesn't conduct electricity as well as most think. There is the possibility that it corroded some terminals inside, but 12 volts in water is no big deal. I had a boat trailer with submersible lights that simply had drain holes in the lens and LED's for lights. Water filled up the housing and while full the lights worked just fine.

Now take an incandescent light with a hot glass globe, touch a drop of water to it, the glass breaks and the filament burns up. Did it on my 1969 Plymouth Fury a while before figuring out the problem. Bulbs were getting expensive.