Yamaha DTXpress/DTXplorer/DTXtreme

OGD,

You obviously missed my post 12663:

"The solution to that is to use a stereo cable and stereo connector and
connect your switch between the connector tip and sleeve and a 150k
resistor between the tip and the ring. There may be other
combinations that work and other resistor values, but that worked on
mine (DTXpress III). I now get closed, open, foot close and splash
sounds from a switch (I only checked the open & closed sounds before)."

That fits in with your findings but I used a resistor instead of my
finger.  My findings weren't accidental - I took the pedal apart,
traced out the circuit and measured all the resistor values!

Keith.