Prius trying to move in park

Yes. I would say at least 60% of the time (at startup). But the pressure it applies seems very minor so it doesn't bother me any. If it is pushing you uphill though, that is more than mine is doing.

 

I too have noticed this but if you look carefully you really don't move, it's the feeling the car is moving/rocking but you not moving inches in a spot.

It's more sensation than movement.

I have actually had someone watch as the car was feeling this inside and they said the car really didn't move, so I have come to just adjust to it. I don't notice it all the time, depends on the grade in which the car sits.

I am going to mention it at my first service but don't expect it will be a problem that need's to be addressed. If your car is moving many inches then that's a different situation.

If you note you are supposed to APPLY your PARKING BRAKE as well when leaving your vehicle. It's in the Manual....

 

Normal

 

I think it is by design, the Prius has a inclination sensor, by applying slight torque to move the car forward to release the pressure on the parking pawl so that it can be released more easily on a slope.

One way to prove this is to park the car facing down the slope and if it will lurch backwards.

 

You don't use the parking brake? Shame on you!

It's normal. There MUST be some play in the "parking pawl" otherwise it would jam in place. The car will move back and forth about 1-2" depending on how much play is in there.

The car will be "driven" forward or back by oil viscosity friction. So when cooler it will be driven by more torque. The car is normally driven by magnetic torque, but in "P" that is off. That is, the MGs are magnetically "locked" or partially locked to ensure the engine torque is transferred to the wheels, and when in "P" there is almost no magnetic torque, which allows the engine or wheels to "freewheel". So the "parking pawl" (actually a gear engaging the housing) and the parking brake is needed to keep the wheels from turning.

 

I agree with that... it was about 37F in the garage this morning and when the engine started (no brake on) the car lurched forward on the pin (1-2") pretty good.
Catches your attention but it certainly didn't feel out of control. Like David said, one way to prevent it is by setting the parking brake. Though I wonder if that would be problematic in really cold temps (freezing pads to the rotors)?

 

The transmission in the Prius is *always* engaged, even when powered down. There is no clutch or torque converter. Because of this, when the ICE starts, torque from the ICE will attempt to push the car forward. The parking pawl will keep the car from moving far, but there is a little play.

Tom

 

I -ALWAYS- use the parking brake (unless I don't because I'm doing something that requires the rear wheels to turn). Check my sig at the side. I do live in "winter" climate. The brakes have never frozen, they have always released just fine. I DO think I need to lubricate the parking brake mechanism in the cabin though. It's probably time.

I can report the parking brake works just fine from 40C to -35C (so far).