This is the schematic for the entire wiper/washer circuit in a GM vehicle. The wiper/washer switch is not part of the wiper motor assembly but is included because it identifies the function of timer and cycle switches built into the motor assembly. The only connections that I have used for props are the Purple (+12 volt for high speed), Yellow (+12 volt for low speed) and Black (12 volt chassis ground). These wires all come from a three-pin connector on the motor itself. Note that you would connect either the Purple wire or the Yellow wire to +12 volt, depending on your desired speed, but never both.