The pump also has built in protection if it detects a leak in the system. If this is the case it can be reset by pulling the fuse out for a minute or so then replacing it. It will then work once or twice before it detects the leak again. (This was the symptom that mine showed before I replaced a leaking actuator.)

My advice; pull the fuse then replace, click closed the trunk latch catch inside the trunk to "trick" the system into trying to pull the trunk closed then listen for the pump. If you do hear the pump during this test, try looking for a leaking hose or failed actuator.

Good luck