Do I check voltage with key off or on and what are the tolerance limits?

Question

I got the code P0178 on my 2005 Chevrolet Suburban ZR71 1500.

These are the voltages I am reading at the plug for the flex fuel sensor.
Key OFF - Pin A 0vdc, Pin B - 0vdc, Pin C - 0 to .6 ohms
Key ON Pin A - 4.97vdc, Pin B - 11.8vdc, Pin C - 0 to .6 ohms
Key ON motor running - Pin A - 5.0vdc, Pin B - 13.97-14.9vdc, Pin C - 0 to .6 ohms

Am I to measure these voltages with the key off or on or with the engine running?

Are these voltages within tolerance?