The Brake light on the dashboard comes on when I travel in a heavy rain, as we had here in NYC last night. I've also experienced this condition after going thru a car wash. The light always goes off after about 15 minutes of driving.

I once had a dealer tell me "there was a ghost in the machine" and they couldn't fix the problem unless it happened when the car was in the shop.

Is something loose that would be easy to fix, or just leave it alone?

 

Do you ever get water inside your lights? That could be one possible cause. Or an exposed brake sensor that gets watery and gives a bad connection....

 

I'd go with the exposed brake sensor.

Is that something I can fix myself?

Funny, just came back in from a hard rain - no sign of the brake light?!