3 wires for well pump - black

[Qwertyjjj]

I've got a well pump that had wires cut/disconnected without labelling. The 3 wires are all black. How do I figure out which is which to splice it back to the motor control.
I can't easily do a continuity test since the splice point is 75m away from the motor control.
In the image c = control, p =pump

Control box as connection points labelled yellow, red, and black.

 

[Valveman]

If you can ohm the wires going to the motor the yellow to black will be about 1/3rd of the yellow to red.