Originally Posted by jon@work

Fuse 15 feeds 12V to stalk terminal 54 (black/violet wire). When the washer button is pushed, a connection is made within the stalk, joining terminals 54 and 53C (black wire). 12V is thus fed to the pump. Instead of the second pump terminal being directly connected to earth, the wire from the pump (black/yellow wire) returns to the stalk (terminal W), where there is a permanent connection to stalk terminal 31, which should be earthed (brown wire).