DDS3/2D Install - Blowing 15 Amp Fuse

[subarusmasher]

I'm having problems with my 2D / DDS3 install - It's worked flawlessly for over a year, but now keeps blowing the 15A pump fuse :cry:

If I test the system by removing a wire from the Pressure switch then the pump appears to work fine, delivering an increasing flow of water, as Rpm is increased.

If i then drive the car, as soon as the WI system is triggered it will blow the fuse.

Any ideas as to what may be causing this, or what to test

Richard