Car stops when I go downhill and need to stop the car

Thanks. I stand corrected. I think I remember video that didn't quite explain the two way motor and assumed that there was a spring involved. I don't remember now which one it was.

 

OK here's a wild guess:
In general, you can NOT have both the brake pedal AND the gas pedal pushed at the same time.
The computer will ignore one or the other.

So.....if you come to a stop and keep the brake pedal depressed, then also push the gas pedal......NOTHING will happen.
Is it possible that is what you did ??

Edit: There definitely is a different problem at work here. As others have said, it should NOT automatically put itself in Park every time you come to a stop.

 

or check the "P" (parking) switch and wiring for a short. I'll bet (hope) that there is some sort of interlock that would keep "parking" from engaging above a certain speed to prevent damage. If the switch was intermittently shorting closed, that would explain the unexpected engagement of parking when the speed of the vehicle dropped below the safety interlock speed.

 

In the GenII, any speed above 7mph, pressing the park button will cause the car to go into neutral and usually emit a beep-beep. If the car is not going into neutral at sustained high speeds, it is unlikely the park button is being pressed frequently and autonomously.

 

Thanks for the info! I certainly was not going to test it!

 

That's how a Prius is supposed to work. You did have a problem. Engine shuts off if it is not needed, i.e. going downhill.

LG-TP260 ?

 

But not at all normal to put itself in park when you cone to a stop sign.