General Adaptive cruise control
- Thread starter Salarden
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General Adaptive cruise control
At a guess I would say no (unless it actually applies the brakes). I may be showing my age here but most brake lights are activated by a switch when the brake pedal is pressed. Is ACC different to ordinary Cruise control? My Cruise Control in UK does not apply the brakes therefore no chance of brake lights coming on.
Same as if you were driving the car, if the car has to actively brake then yes the brake lights will show, if it’s just slowing down with the traffic with no need for the brakes then no the brake lights won’t show
Do you mean the fact you can accelerate and decelerate with the controls as im sure that doesn't apply your brakes and hence no brake light. Just slows the engine I would imagine
Well the brake lights "might" come on. The only way to know for sure is for an on road test with a tailing car.
Only say this as brake pedal switches bring brake lights on. On the same tack hazard or indicator switches bring the indicators on.
BUT on 500s (early ones for sure) when the ESP kicks in the hazard/indicator lights flash rapidly. On F1 cars when de-rating the rear high intensity bad weather light flashes.
As official detailed technical info is difficult to obtain these days then user observation and testing is the next logical test.
I believe on some trucks when the speed limiter kicks in on downhill runs the brake lights are illuminated and the brakes may or may no be applied depending on retardation required.
Only say this as brake pedal switches bring brake lights on. On the same tack hazard or indicator switches bring the indicators on.
BUT on 500s (early ones for sure) when the ESP kicks in the hazard/indicator lights flash rapidly. On F1 cars when de-rating the rear high intensity bad weather light flashes.
As official detailed technical info is difficult to obtain these days then user observation and testing is the next logical test.
I believe on some trucks when the speed limiter kicks in on downhill runs the brake lights are illuminated and the brakes may or may no be applied depending on retardation required.
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twobigdogs
Member
ACC is totally different to ordinary cruise control. It will apply the brakes if the car is coming up too fast to the car in front. Hence “Adaptive Cruise Control”.
Agreed...but....do you actually know what the body computer and engine management have done/signalled?
What may seem logical for many is in many cases illogical to those who programmed the various ECUs of the car. We get it wrong. They get it wrong. Have to fall back to basics. Go test!
I Have experienced the ACC slowing the car quickly when another car pulls into my path and am concerned that following vehicles will have little or no warning if the brake lights do not come on. It appears I may have to take up the option of a following car checking for me.
If ACC uses the brakes to slow the vehicle, it will show the brake lights. If it releases the accelerator, no brake lights show. Just like if driven normally.
If it needs to use the brakes to slow the car, it is important to warn following traffic. Not to use the brake lights would create a risk of a rear shunt.
Adaptive cruise is not there to allow the driver to relax and become distracted. It is there to help maintain steady progress, with safe following distances.
The driver particularly needs to pay attention when approaching slip roads, or when following another car and both are catching a slower vehicle. If the vehicle ahead changes lane, onto the slip, or to make an overtake, the ACC will increase speed as the radar is now 'seeing' more space. If the difference between actual speed and set speed is large, the car might accelerate quite firmly, but then moments later 'sees' the next vehicle and then brakes. In such a situation it is better for the driver to anticipate this, and use the cancel button, add speed gently to close the gap, then resume cruise to maintain speed and distance.
If it needs to use the brakes to slow the car, it is important to warn following traffic. Not to use the brake lights would create a risk of a rear shunt.
Adaptive cruise is not there to allow the driver to relax and become distracted. It is there to help maintain steady progress, with safe following distances.
The driver particularly needs to pay attention when approaching slip roads, or when following another car and both are catching a slower vehicle. If the vehicle ahead changes lane, onto the slip, or to make an overtake, the ACC will increase speed as the radar is now 'seeing' more space. If the difference between actual speed and set speed is large, the car might accelerate quite firmly, but then moments later 'sees' the next vehicle and then brakes. In such a situation it is better for the driver to anticipate this, and use the cancel button, add speed gently to close the gap, then resume cruise to maintain speed and distance.
twobigdogs
Member
My experience of using these things on cars I have been loaned or given in the last few months is that the car will accelerate firmly as you say, but the radar is looking further ahead the safe distance. If you where doing 70 and the car in front was doing 60 then he car would see it and stop accelerating long before you got too close to the car in front, of that car in front was going much slower, say 40-50 then yes it would likely need to gently brake as engine braking alone would not slow you in time.
These systems are quite clever and drive the car in much the same way as a person would and therefore if the brakes are used then the brake lights will come on, if they are not used then they won’t if you slowed on engine braking only for example.
My wife has a Mini Countryman and although it doesn’t have radar cruise control, you can set the car so it won’t go over a certain speed, set it to 50 and it will go no more than 50 unless you bury the throttle for an over take or similar. If you’re going down an hill and the car starts to creep over 50 the car will gentle brake and the brake lights will come on, to slow the car down and keep it within the set speed.
Well for the TRW braking system fitted to 500X (UK/EU for sure) the definitive words on this are:
Activation of brake lights above a deceleration threshold permits the indication of vehicle
deceleration to other vehicles by simulating braking.
This function permits the activation of the brake lights for at least 1 second in two situations:
during the operation of the Adaptive Cruise Control (ACC), Hill Descent Control (HDC) or Hill
Start Assist (HSA), the brake lights are activated when the brake fluid pressure exceeds a
minimum threshold value; during Electronic Stability Control (ESC) or Trailer Sway Control
(TSC), when the deceleration exceeds the set threshold.
Activation of brake lights above a deceleration threshold permits the indication of vehicle
deceleration to other vehicles by simulating braking.
This function permits the activation of the brake lights for at least 1 second in two situations:
during the operation of the Adaptive Cruise Control (ACC), Hill Descent Control (HDC) or Hill
Start Assist (HSA), the brake lights are activated when the brake fluid pressure exceeds a
minimum threshold value; during Electronic Stability Control (ESC) or Trailer Sway Control
(TSC), when the deceleration exceeds the set threshold.
