Shutting down the ICE

My understanding is the engine is shutoff by stopping spark and fuel injection but its not through a kill of the overall engine ecu. Obviously it is still in ready and things like the water pump and ac still run. Often the car is moving and driving with the engine off, either coasting, regenning, or driven by electric only. Without rpm the coils and injectors are off but the ecus are still active. The MIG1 motor generator clearly starts the engine when needed by spinning it and ecus will read the rpm, crank and cam positions to time the spark and fuel.

Now that I have provided input I am sure some otherwise quiet chaps will chime in.

 

I probably would not say the ignition stays energized since the plug coils are off at all times unless momentarily powered to produce an individual spark. The controls are active. Part of the soft start is the mig1 motor can spin the engine at 1000 rpm, fast enough to quickly determine timing. It avoids a conventional engine's slow rpm crank which produces a longer and rougher start.

There are slightly different mig1 starting scenarios when the car is driving forward and another when mig2 is driving the car in reverse. By the way mig2 is the only device driving the car in reverse.

Going through the Weber auto videos "starting" at the earlier generations helps.

Another resource is the linked Toyota Prius gen 1 and 2 Technical Course. Most of the Gen 2 descriptions apply to Gen 3 with a few exceptions. For example Gen3 does not use a drive belt in the transaxle and does not have a bladder in the gas tank. The Prius v wagon is a gen3 but with a lower final drive gear (higher numerical), improved ac and a few features like dynamic pitch and bounce control.

http://stuff.jaygroh.com/prius/Prius%20Info/Official%20Toyota%20Info/References/Technical%20Training/Hybrid%20System%20Overview.pdf