Rx400h jerks when in Parked (P) gear

[Ess Ess]

Hi everyone,

I'm new here, as well as a new Lexus owner (2007 RX400h) I've noticed that when I'm sitting in my car while it's on (lunchtime at work, I sometimes sit in my car with the engine on to warm up and listen to the radio), the car seems to jerk. It feels like a slight backward jerk and happens once or twice within the first 8 minutes of the car being on. It had a full service with Lexus and MOT passed the week I bought it (almost 3 weeks ago) and has LOW mileage (36k). Timing belt, water pump etc all checked and changed if needed. 

Is this jerking normal and something anyone's experienced before? 

Thank you in advance 

[Tel]

Nothing to do with the Auto Handbrake/rusty surfaced callipers ?

Tel

[Ess Ess]

I have NO clue I'm afraid, just needed some suggestions or advice as I'm such a newb 😐 Is this something that happens with the Auto Handbrake?

 

[Britprius]

42 minutes ago, Ess Ess said:

Hi everyone,

I'm new here, as well as a new Lexus owner (2007 RX400h) I've noticed that when I'm sitting in my car while it's on (lunchtime at work, I sometimes sit in my car with the engine on to warm up and listen to the radio), the car seems to jerk. It feels like a slight backward jerk and happens once or twice within the first 8 minutes of the car being on. It had a full service with Lexus and MOT passed the week I bought it (almost 3 weeks ago) and has LOW mileage (36k). Timing belt, water pump etc all checked and changed if needed. 

Is this jerking normal and something anyone's experienced before? 

Thank you in advance 

Sharan welcome to LOC.
The jerking you are referring to is normal while in park, and ready mode. Because of the way a hybrid transmission works it is always in gear. There is no true neutral, reverse gear, or actual gear changes. It is all down to a computer arranging the supplies to electric motors. Reverse is the electric motor being turned backwards. These motors can also act as generators.
If you put the car in ready mode, and park the engine will start, and stop under control of the computer depending on if you have the heater on, the state of charge of the high voltage Battery "not the 12 volt battery" and the engine temperature.
The engine is started by the same electric motor that drives the car along "there is no normal starter motor, and no normal alternator" it is this starting the engine you can feel. As it turns the engine it also tries to move the car. There is a similar effect when the engine stops.
Never sit in the car in ready mode with the car in neutral as the system cannot look after itself in this condition.

John.

[Tel]

Try sitting in Park with the Handbrake OFF & see if it still Jerks.  

Latesrst Cars have Autobrake when you select Park but yours will be manual select so just try it without

Tel

[Ess Ess]

44 minutes ago, Britprius said:

Sharan welcome to LOC.
The jerking you are referring to is normal while in park, and ready mode. Because of the way a hybrid transmission works it is always in gear. There is no true neutral, reverse gear, or actual gear changes. It is all down to a computer arranging the supplies to electric motors. Reverse is the electric motor being turned backwards. These motors can also act as generators.
If you put the car in ready mode, and park the engine will start, and stop under control of the computer depending on if you have the heater on, the state of charge of the high voltage battery "not the 12 volt battery" and the engine temperature.
The engine is started by the same electric motor that drives the car along "there is no normal starter motor, and no normal alternator" it is this starting the engine you can feel. As it turns the engine it also tries to move the car. There is a similar effect when the engine stops.
Never sit in the car in ready mode with the car in neutral as the system cannot look after itself in this condition.

John.

Thank you so much, John! Well explained and makes sense, too.

 

Phew! Thought I had too much of a good thing with the car, turns out it really is!

[Gliderpilot]

56 minutes ago, Britprius said:

The engine is started by the same electric motor that drives the car along "there is no normal starter motor, and no normal alternator" it is this starting the engine you can feel. As it turns the engine it also tries to move the car. There is a similar effect when the engine stops.

Not quite true, there are in fact two motor generators at the front of the car, a larger one drives the wheels and is permanently engaged and a smaller one which is used to start he Internal Combustion Engine (ICE) and mix the power between the  ICE and the Motor connected to the front wheels. So when the "Brain" calls for the ICE to start the second motor turns to start the ICE and the reaction of the ICE starting is transferred to the wheels but because it is in Park they can not turn so play in the transmission is taken up and this feels like a jerk. Even our Yaris HSD does this.

[Britprius]

It is MG1 that starts the engine, but since this is connected to the sun wheel directly it is possible for it to assist in driving the wheels. When the ICE is running MG1 can be powered, and even made to change direction altering the effective gear ratio. In the Prius gen2 "othere Toyota variants differ slightly" MG1 can run from plus 10,000 rpm to minus 10,000 rpm with the car moving only forwards, depending on road speed and ICE rpm.

I know there are two motor generators in the standard system, but I was trying to explain the basic system to "no disrespect intended here" a novice. The RX, and some GS 4 wheel drive have a third motor generator. For the RX in the rear diff there being no mechanical drive from the transmission to the rear wheels, and with the GS the front wheels are driven by a similar system.

John.

[Ess Ess]

19 hours ago, Britprius said:

It is MG1 that starts the engine, but since this is connected to the sun wheel directly it is possible for it to assist in driving the wheels. When the ICE is running MG1 can be powered, and even made to change direction altering the effective gear ratio. In the Prius gen2 "othere Toyota variants differ slightly" MG1 can run from plus 10,000 rpm to minus 10,000 rpm with the car moving only forwards, depending on road speed and ICE rpm.

I know there are two motor generators in the standard system, but I was trying to explain the basic system to "no disrespect intended here" a novice. The RX, and some GS 4 wheel drive have a third motor generator. For the RX in the rear diff there being no mechanical drive from the transmission to the rear wheels, and with the GS the front wheels are driven by a similar system.

John.

You are right - complete novice here! Thank you all for your help 

[Ess Ess]

19 hours ago, Gliderpilot said:

Not quite true, there are in fact two motor generators at the front of the car, a larger one drives the wheels and is permanently engaged and a smaller one which is used to start he Internal Combustion Engine (ICE) and mix the power between the  ICE and the Motor connected to the front wheels. So when the "Brain" calls for the ICE to start the second motor turns to start the ICE and the reaction of the ICE starting is transferred to the wheels but because it is in Park they can not turn so play in the transmission is taken up and this feels like a jerk. Even our Yaris HSD does this.

Thank you!