How can you identify the power loading connection on a connection diagram or on a control unit?

At first i thought the power loading would be clearly marked on the control unit connector? A friend told me terminal designation 31L?

 

You look at the schematic diagram and visualize where the current will flow....

 

Sorry I dont understand what you mean, all I mean is how do you identify the power loading connection on a circuit digram or controller?

 

I'm unclear what you mean by a 'power loading connection'. Only some circuit diagrams are labelled with input/output labels. With other diagrams (such as Mike was referring to) you have to understand the circuit enough to deduce the power input/output points.