Hi MP, thankyou very much for your reply. There is nothing on the unconnected pins of the round plugs. I'm not sure about the signal on the different colors of wire, if you explain the right way to test it to tell you what you need I'll come back to you on it. With the pedal open I can short and successfully change between OD2 and clean channels by shorting the yellow and the orange for the clean channel, and the green and red that connect to the od2 switch. I short these by putting a screwdriver touching both wires at the 15 pin plug end. I've tried shorting using just these 4 wires on a 15 pin plug but it doesnt work right, it needs the circuit that links between the switches (burgundy wire), that eventually returns to the 15 pin plug via the light blue wire. I'll help you help me if you explain how to answer other specific questions as I've just decided to start working on electrical projects.