1995 Oldsmobile Aurora speedometer and tach

My speedometer and tachometer do not work. They quit suddenly. The control center, or whatever you call it, quit along with heater blower and heated seats. I found a blown fuse in the side panel and replaced it. Now just speedometer and tach are not working. I found a fuse blown under backseat but every time I replace it, it blows again. I would like to know if and where the short is. I do not want to spend a lot of cash to fix it. Please help if you can.
Thanks