Rear Wiper Motor or Pump?

[98JimmyKat]

I am having issues with my rear wiper. I am unsure if it is the pump or motor or both that has gone bad. When pressing the rear wiper button, I hear a noise but there is no fluid nor do the wipers move. I do not have any issues with the front ones, just the rear. How do I know what part is needed to be replaced? Or just replace both???