I just installed a new BMW 712, it updated the firmware twice 2.XX something then to upgraded to 4.XX version so far so good. But it always shows about 19 Amps no - or + just 19 amps. So I started to look for the drain but there isn't any. I turned everything on and the amps never change. Volts do drop with the load but the amps are steady at 19 ish... So then I plugged in the charger ... guess what still says 19 amps. Being in the 5th wheel I just disconnect the - side and inserted in the shunt.
White bottom is going to the 5th wheel and Black is going to the negative side of the battery. On the battery there is nothing but the black cable.
I did connect both voltage red wires to the shunt but I haven't hooked up a second battery yet, doubt that matters
As I recall the charger was unplugged as well I never recall ever seeing a - sign for current. 
