Rear deck sunscreen activates and comes up without operator activating it. and it will not go back down without manual assistance. with assistance when it does go down there is a loud grinding noise and then it will come back up. to correct this situation requires replacement of complete assembly. (dealer quoted $1674.86) or pull the fuse and deactivate the rear sunscreen. safety issue is that sunscreen up at night or during inclement weather restricts rear vision and driver can't do anything about it unless he happens to know which fuse to pull and where it is located. when asked why toyota has not corrected this issue, dealer speculated that since this is an avalon only problem that the numbers of failures are likely small. my response was, that may be true but by researching this issue on the internet, it has been a problem since at least the mid 1990's until at least 2013 and probably beyond and toyota has not recalled or fixed the problem so far as i can tell. regards our specific car a 2012 avalon, it is a feature almost never used and as of this date the car has less than 18000 miles on it. mileage and age seems not to be a factor in the failures. it seems more likely a poor design of the feature itself. as far as when it happens and where, it can happen anytime the car is running, in the driveway or while driving..