Surendra

[Surendra]

i have just acquired a new premier model but on running the same i find that the Adaptive Cruise Control stops working when the car slows down to 30 mph and needs manual braking

the Speed Limit Display (SLD) for a start does not display on the main map, it only shows on the display on the dash board and shows various speeds from 30 to 140 at random places (90mph on a 30mph road.

The Lexus Centre is at a loss what to do

Do any other drivers of the above car have same problems??

[sorcerer]

I'm afraid I haven't got an answer for you but surely, if you've only just got the car then just take it back to the dealer and let them sort it - it's not up to you to find a solution for them.

[Dinho]

Maybe ask in the IS300H forum..

[janey]

Moved to IS300h section 

[rayaans]

Manual says it switches braking over to driver under 30mph. It's not a full range cruise control system

[ganzoom]

On ‎22‎/‎07‎/‎2017 at 6:19 PM, Surendra said:

i have just acquired a new premier model but on running the same i find that the Adaptive Cruise Control stops working when the car slows down to 30 mph and needs manual braking

 

Our pre-face lift IS300H has adaptive cruise control, it's designed not work below 30mph/stop the car completely as it's not clever enough. You also need to take some care with other cars merging into your lane as it can accelerate/decelerate in appropriately. It also doesn't 'see' motorbikes.

If you want an adaptive cruise control system that does all the work for you, including stopping/restarting you need to look else where.

[Ian J. Parsley]

Surendra et al,

It would probably be worth having a separate thread on adaptive cruise control in general. I think the system is excellent but you do have to understand what it is (and isn't).

Firstly, regular cruise control essentially means the car takes control of the accelerator. This means you set the speed and the car will operate the accelerator to stay at that speed, come what may. Of course, this isn't much use if there is an obstacle in front (the car takes no account of that), nor on a significant downhill stretch (because that needs the brake to be employed to maintain speed, but regular cruise control affects only the accelerator). This applies from 40kmh up. Cool.

Secondly, early adaptive cruise control systems added a radar to take account of traffic in front. With these, if the car detects an "obstacle" moving in the same direction, it assumes it is a vehicle and will move off the accelerator to bring speed into line with that vehicle. This still only applied from 40kmh up. Great.

Thirdly, what you have (I think - it's what I have anyway) is advanced adaptive cruise control with pre-crash alert. This is adaptive cruise control which also takes control of the brake pedal. Because of this, it will do a few things: a) it will maintain speed even on downhill stretches; b) it will speed up only when you straighten the car up (so as to enable you to maintain speed following a vehicle on twisting stretches); and c) it will function at below 40kmh *if there is a vehicle in front*. Magic.

Now then, I'll take a guess at what is happening in your case. 

Firstly, you can only operate the system *if you are travelling above 40kmh or you have a vehicle in front*. Either of those will do, but you do need one or the other. In practice, this means you'll need to negotiate things like large roundabouts yourself.

Secondly, the speed in the dash in front of you is *not* the speed limit. It is the speed you have set the adaptive cruise control to. You can set this whenever the system is working ("radar active"), i.e. whenever you are travelling above 40kmh or you have a vehicle in front, using the lever (up or down in increments of 5mph). In theory you can do this even when stopped behind another vehicle (in which case you will be told "Waiting" and will then see "Preceding vehicle movement" - when the latter happens, flick the lever up and the car will increase to the speed you have set or to the speed the vehicle in front is doing, whichever is lower.

I hope that makes some sense - moderators may wish to consider putting this post in another general thread on adaptive cruise control, because it can be confusing.

[rayaans]

10 hours ago, ganzoom said:

 

Our pre-face lift IS300H has adaptive cruise control, it's designed not work below 30mph/stop the car completely as it's not clever enough. You also need to take some care with other cars merging into your lane as it can accelerate/decelerate in appropriately. It also doesn't 'see' motorbikes.

If you want an adaptive cruise control system that does all the work for you, including stopping/restarting you need to look else where.

The facelift uses the same acc I think as the instructions are the same.

The cruise control in my RX will stop but just needs a prod on the throttle to start again after car in front has moved off.

But this is full range cruise control whereas the IS is adaptive but not full range