GS 450H 2011 CVT gearbox

[Mihanicos]

Recently when going down mountain roads with gradients in excess of 10% I noticed that the engine braking when in 5th, 4th and 3rd gears was much less than before. The difference in braking between these gears was also very small.

The car displayed no trouble codes and neither the Techstream. There has been no loss of transmission fluid. The 12v Battery has gone flat a couple of occasions due to absence abroad but the car was ok after recharging the Battery. The only items to initialize after reconnecting the Battery was the steering by turning it fully in both directions and the tyre pressure sensors.

I would be grateful if anybody can give any advise as to the cause of the problem.

Chris.

 

[Britprius]

If the traction Battery is fully charged the so called engine braking is minimal. The reason being the energy produced by the motor generators has no where to go so the engine revs just rise.There are no separate gears as such for any purpose including reverse. See my thread in the GS450H forum entitled "How the GS450H transmission works". Any gear is purely an electrical state of the motor generators.

 

John

 

[Britprius]

I should have added to the above that there is a limit to how much "engine braking" can be used. To much risks locking up the rear wheels thus loosing control. This is because "unless you have the 4 wheel drive version" engine braking can only be done via the transmission to the rear wheels. If any slip of the rear wheels takes place engine braking is either removed or severely reduced till all wheels rotate at the same speed. 

Not doing this would mean severe oversteer "the rear of the car overtaking the front in a spin".

John

[Mihanicos]

Thank you very much indeed for sharing your knowledge and experience with me.

Your threads were very enlightening and the videos explained very clearly in detail how everything works. I knew that the braking was regenerative through the motors but I did not have a full drawing of the car's gearbox to understand how everything works. I bought viewing time from Lexus website to look up relevant information but all I could access was how to change gearbox oil.

I will check the car's behaviour in the next few days and I will know if it is back to normal.

I take this opportunity to thank you for your help and the Lexus owners club of uk for hosting me.

 

Chris.