Originally Posted by rcompart

The wiring would be on par with that of a keyboard from a computer, multiple commands sent across one wire based on impedance changes in the circuit. The shift wire is just that, one wire. It sends a signal telling the PCM the you want to upshift or downshift. It's not like a regular switch that when the circuit is closed, it sends power through. Another thing you'd have to take into account is that it employs staging so when you hold it, it goes back into drive mode, when the switch is held down, it builds up to a point and then sends another signal that the transmission should go back to auto mode.