Just AM2 through the inverter W/P relay. That relay is triggered by the power source control ecu (on IG2D ckt) . Posted via the PriusChat mobile app.
I second this suggestion. I've change 2 of these pumps without completely flushing the coolant. No turbulence in the reservoir initially in both cases until I cycle squeezing the hose going into the pumps. The first pump was OEM. The second one that stopped working right was an Autozone unit. It just started working intermittently and only on at max power then. That one lasted nearly exactly one year. Hoping the Aisin one that replaced it does far better.