The manual says :
During scheduled maintenance, check the power steering
fluid level at the power steering fluid reservoir. Normally,
it will not be necessary to add power steering
fluid.
Before removing the reservoir cap, wipe the outside of
the cap and reservoir so that no dirt can fall into the
reservoir.
The power steering pump has a dipstick. Fluid level
should be maintained at the proper level indicated on the
dipstick. If necessary, add fluid to restore to the proper
indicated level. With a clean cloth, wipe any spilled fluid
from all surfaces.
I would take that to mean with power off.
HINT: If it's dark, use your cell phone light.
Look inside the reservoir, if the fluid looks frothy, then it's low. There should be no air in the fluid.