Nissan Patrol 4x4 (Africa)

I was under the Patrol over the weekend as the pump on my 60L water tank that was on the Patrol when I bought it, seems to have kicked the bucket. The pump makes a noise, but no water comes out the tap fitted on the rear bumper.

The water tank is fitted where most other Patrols have their subtank, but mine never had the subtank fitted as standard. So I followed the hoses and electrical wiring to prepare to fit another pump I have ( http://kamoer.com/Products/showproduct. ... 67&lang=en ), but landed up finding this thing connected inline between the existing pump outlet and the tap. There is an electrical connection spliced in to this thingy that feeds power to the pump from the on/off switch I have fitted on the drawer system. What is this thing? If it is a pressure sensor switch, well it has never worked, cause if you close the tap with the pump running, the pump keeps on running. I then thought it may be a switch that if the tank runs dry the pump it will shut off the pump, but it also just keeps on running so I think whatever it is ....it is not working. So what the heck is this thing??
Here is a few pics of the tank and existing pump (white tube looking thing), and the tap at the back.

Looks like a little solenoid-operated valve to me. Possibly a diaphragm valve.

I suspect it is superfluous to your installation.

yeah, I also think its a waste to have it. Thanks Peter

It is from a Camper bus .. Ford Transit or some such that came out with running water. Not the Volkswagen though. Transit / Bedford ..
Oompie thinks this was replaced with the system you now have because the "thingy" got faulty.

[I still prefer my gravity feed system

Ahhh....ok. thanks Oom Mac