Ric, after opening the WSII, on the right hand side of the cabinet is the mother board. On the bottom left hand side of that board, there is a 6 pin harness (the board will say car wash relays on it), the first 4 terminals are for the washes. On my wash, the first terminal is the cheapest wash and the fourth terminal is the highest wash. Like Mep said, these relays send a 24vdc signal to the wash computer to activate a particular wash. You should be able to see what color wires are hooked to these terminals and trace them back to your computer inside. Hope this helps.