Yellow is connected the black and orange is connected to red. Thanks for checking. Assuming Pin 5 is the square solder pad, then the voltage between Pin 5 and Pin 2 and between Pin 5 and Pin 3 are both in the range of 2.0 MV DC and 0.3 Volts AC. They don't appear to change when I blow the train horn. I made the measurements with the MAX connected to both the Legacy Cab-1 RS232 and to the powered-on Mega.