I have 2015 Highlander that is 36 months old. When I took it into dealer three months ago they said condensation was on right inner taillight and would cost $330 to repair.
Now left inner taillight has 2 or 3 ounces of water sloshing at the bottom along with condensation. The right taillight has completely dried out.
Highlander is always kept outside--had 10 inches of rain in the past month.
Have no idea how water is getting into both taillights. Appears to be manufacturing defect.