> Is there any way to tell whether it's a 
> faulty pump in the water tank that's to  
> blame, or if it's the faucet itself?

Connect the two wires on the faucet to eachother, thus bypassing its switch.
If the pump turns on, your faucet's switch is bad. If it doesn't, leave the
wires connected and check for power and ground at the pump. If there is
power and ground there, the pump is bad. If not, you have a wiring problem
or a blown fuse.

Of course we have pumps and faucets in stock once you determine which you
need.

- Ron Salmon
  The Bus Depot, Inc.
  www.busdepot.com
  (215)  234-VWVW

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Toll-Free for Orders by PART # :  1-866-BUS-DEPOT