I wanted to get some feed back on the cruise control. I have a 92 ls400 and whenever I have the cruise control engaged and I am going down a long hill it feels like the the speed is being controlled by moving the throttle on and off rather than smoothly reducing throttle. The speed is maintained at the set speed but the "seat of the pants feel" is as described. Is this normal for the ls400? On flat roads or small hills it feels fine. This is cruising at freeway speeds (60 to 80 mph)

 

My car behaves the same way when the cruise control i set for a relative low speed (70-80 km/h, ~43-50 mph) and going downhill (the hills have to be quite steep). I do think this is normal. What happens for me is that the car back of so much in the gas so the lockup disengages,the same behavior as when you drive without the cruise control and lift off the gas totally. This happens because of the hill is so steep that car would almost maintain all it's speed even when you let off the gas.

Hope this was an answer on your question

 

Thanks for the answer. I would think a car of this quality would do better, are you sure this is normal?

 

To be honest I don't have any problem with it. On my car you hardly feel it. Can't be 100% sure this is normal for these cars but others cars I have driven with cruise control behave similar accept they have had manual transmissions. As I sad before, this occurs because the car have to give so little gas to maintain speed so you go past the point where the TPS (Throttle Position Sensor), tells the Lock-Up to disengage. Maybe the behavior would be worse if your TPS is not correctly adjusted. Just guessing here, so don't take my world on it. Ask a good Lexus mechanic about this if you still think your cars behavior is not normal.

 

My 90 LS400 does the same thing going downhill.

 

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