Nissan Repair Questions? Ask a Mechanic for Answers ASAP
pin 1 is your 12 volt pin.
pin 3 is the ground wire. This will have continuity to ground.
The final wire is your signal wire. I am not sure where you are getting 20 volts on a 12 volt system, but the last wire is the signal wire and would be the center wire.
Yes, hopefully this info will help you out, but let me know if there is more I can try to do from here. Also, don't be afraid to open the harness and get the wire colors.