There are only 6 possible combinations.(12 if you reverse the leads to the meter)
Black - Red = continuity (0 ohms)
Black - Yellow = open (infinity)
Black - Green = open
Now try
Green - Red
Green - Yellow
Yellow - Red
You might try the continuity test backwards in case there is a diode preventing a complete circuit.
Red - Black
Red - Green
Red - Yellow
Yellow - Black
Yellow - Green
Green - Black
It seems red would be constant and the grounding would have resistance. (Black, Yellow, Green)
