Regarding previous post. I obtained two such devices from a junkyard. $10 . Problem fixed! (I had a series of problems.. first the tailight . then the stop light.. prior stoplight portion of trunk.. All fixed with replacement part! Parts houses couldn't even find it in the books. On line parts couldn't find it. Toyota said it would cost $190.00! Junk yard didn't know what it was or where it was.. I went with them and got the part. Its under the lining above the left rear wheel.

 

I own a 1986 Camry and I've had the same problem. However, in my car the lamp failure sensor is located on the right side, inside the trunk, above the right rear wheel, underneath the lining and behind a side metal body piece, but not hard to find it.