Was intermitent for a few days now doesnt work at all. The button lights up and I looked under the seat and the harness is connected and looks fine. Passenger seat works still. Any suggestions before I start pulling things out?
I'm with you. Mine went out a month ago. I can get mine fixed under my factory warranty but my wife won't let me take the car in to the dealer until after the baby is born (can't be without the car).
Heater elements in the seats fail commonly in all heated seats. Generally you will get a hot spot in the seat when it does work and after a while of the intermittent failure it will just give up.
to fix the element involves romoving the seat, taking everything apart, removing the old element (heating pad), and putting it all back together with the new element.
Because the but and back heaters are in series you will loose heat at both locations even though the but element is almost always the fault. you can remove the wires for the but at the harness and jumper the harness. This will give you heat back at the back element.
Thats the short version of where I think you are at.