On Feb 5, 2:40*pm, dumbstruck wrote:
Why would a dishwasher make a hammering sound when filling? It severely shakes the copper fill pipe. Thx

It could be that the valve is opening and closing rapidly causing
water hammer.

That answers your question. Now I suppose you are going to ask:

Why would a dishwasher fill valve open and close rapidly?

Could be:

1 - A faulty fill valve
2 - A faulty float switch sending erroneous signals to the control
board
3 - A faulty control board.

Cleaning the float switch would be my first suggestion.

Bench testing the valve would be my second (or test it in place with
an external power supply if possible)

I don't know how you would test the control board. Are there any
diagnostics listed in the manual?