Two problems related to brake light have been reported for the 2008 Toyota Avalon. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2008 Toyota Avalon based on all problems reported for the 2008 Avalon.
On November 2018 I noticed that my rear deck mounted brake light was out. I thought it was a bulb but the very next day it was back on again. This continued for about a week so I took it to the Toyota dealership and they told me it would be about $400 to take off the rear deck just to see what the actual problem was. I have seen multiple Avalon's with this same unsafe issue. The vehicle also will not pass state safety inspections with this issue. I think an investigation should be conducted on this highly unsafe issue.
The third brake light or the upper brake light works very intermittently. This is a safety issue. Most Avalons on the road in this body style have the same issue with a defective third brake light. The dealer wants over $500 for the part alone. The light works once in a rare rare while. I called Toyota headquarters in torrance, CA. , they suggested I contact you. This occurs when sitting still or driving on streets and a highway.