Where to tap speed sensor signal?

[PowerDubs_imp]

Sorry guys. Any time I have tested for voltage in a car, in a house, in a appliance or a device all I have ever needed to do is one lead to whatever source I am testing and one lead to chassis.

In this case since the power commander is only wanting one wire input, I am unsure how that is any different than my meter lead.

Also confusing is that the power commander has a speed input spot, but in many of the directions online they say some bikes can use the 0-5v input instead if needed. I think there is a spot in the software to tell it which input you are using when you set it up. They don't give much technical details on what exactly the speed input requires or how it functions.