using a suction syringe, remove some of the coolant out of the reservoir to the level between the upper hose and the lower hose. start the car on EV mode to activate the pump and watch the coolant flowing out of the top hose. and that confirms that the inverter coolant pump is working, because the sound of the pump by itself does not confirm that it's doing enough circulation. in NEWER Toyota hybrid models, it is hard to see the turbulence inside the reservoir comparing to the older Toyota Hybrid models.
using a suction syringe, remove some of the coolant out of the reservoir to the level between the upper hose and the lower hose. start the car on EV mode to activate the pump and watch the coolant flowing out of the top hose. and that confirms that the inverter coolant pump is working, because the sound of the pump by itself does not confirm that it's doing enough circulation. in NEWER Toyota hybrid models, it is hard to see the turbulence inside the reservoir comparing to the older Toyota Hybrid models.