I have a 2004 54plate 530d sport. The problem I am have is as followed, when pressing the heated seat button on the drivers side seat it blows a fuse which also stops my drivers seats which is fully electric from working, Replace the fuse and the seat works as it should, but as soon as I turn on the heated seat fuse blows again, What also happens is the 3 lights for the heated seats just stay on. Anyone else ever had this problem.

 

You probably have a broken heater element in the seat base or back. I have virtually the same car and both my seat bases have been changed as the element blew. I had a hot spot on the rear outside edge.

Hope this helps.

 

More preciously your heating elements have shorted like what happens in electric filament stoves. If the filaments are open your fuse won't blow but the heater won't function.