It is not under the seat it is where your feet go if you were sitting in the pass seat hence floorboard. I would pull the carpeting down and remove the metal plate and get to the amplifier (it has a becker sticker on it and check out the small black wire with a test licht and listen to the stereo and if the test licht goes out when the door subs cut out then there is a turn on problem witht the tuner module or a bad connection. Other wise you can send your amp to my repair center and we can rebuild it and send it back to you. If you need to contact my repair center you can @
www.lajollaaudiorepair.com
Scott@lajollaaudio