I noticed today that when the other cars stationary at the traffic light, my car does not brake automatically. If i did not press brake pedal, car would hit the car in front of me.

 

But, when my car moves on the road, the system works perfectly. I only choose speed and after that my car accelarete or decelerate; in compliance with the traffic when needed.

 

I always use the same settings for the assistances, i do not change anything. When i came to work i controlled the settings and everything was marked as it should be.

 

There is no warning light or warning voice.

 

Is there anyone who has experience or information for the problem?

am I the only person thinking that emergency braking assistance is an emergency system and not something you should be relying on in traffic?

That's what the brake pedal is for.

FYI if you're talking about when you have ACC enabled (which will bring you to a stop if the vehicle you are following slows & stops) then the handbook explicitly states it doesn't stop for stationary objects. 

20 minutes ago, Winston_Woof said:

am I the only person thinking that emergency braking assistance is an emergency system and not something you should be relying on in traffic?

That's what the brake pedal is for.

FYI if you're talking about when you have ACC enabled (which will bring you to a stop if the vehicle you are following slows & stops) then the handbook explicitly states it doesn't stop for stationary objects. 

The bit you highlighted doesn’t seem to apply to my car, it certainly did when I almost rear ended a caravan which didn’t have any lights and reacted before I did 😬

 

I remember it well because I passed solids almost, had a red warning pop up then it jammed on the brakes.

47 minutes ago, Danoid said:

The bit you highlighted doesn’t seem to apply to my car, it certainly did when I almost rear ended a caravan which didn’t have any lights and reacted before I did 😬

 

I remember it well because I passed solids almost, had a red warning pop up then it jammed on the brakes.

That will be a seperate assist system kicking in.

If you are driving on ACC it will not stop for stationary vehicles although automatic braking may intervene seperately.

However this is an emergency assist system and should not be relied on for daily driving IMHO

Can you change the distance on the assist the same as the ACC?

1 hour ago, Winston_Woof said:

am I the only person thinking that emergency braking assistance is an emergency system and not something you should be relying on in traffic?

H*11 NO you are not the only person thinking this!

51 minutes ago, Blue8793841 said:

Can you change the distance on the assist the same as the ACC?

I believe you can change the sensitivity somewhere

@enoktakenokta - Traffic Jam Assist and Adaptive cruise both work by "following a moving object".  It needs a reference.

 

Hence in traffic, if ur behind a moving car in ur lane, and it comes to a stop, ur car will stop too. 

If it moves off, urs will follow.

That's wat ACC does.

 

If however there is no one in front of u, and ur approaching traffic already stopped at a junction, then YOU have to brake.  ACC will NOT brake for u!!  Reason being was that it didn't have a reference point (car to follow) before the stopped/stationary car suddenly appeared.

You have to think how it works. If you are approaching a bend, the radar is reflected off houses, street signs etc. there are lots of things straight ahead of the car, the radar doesn’t know that the road bends before you get to those houses etc. You don’t want it to jam on the brakes every time there is a bend!

 

The system use Doppler, ie the change in frequency of reflected radar signals when there is a speed difference between your car and whatever the radar reflects off. Same concept as speed cameras.

 

So if the radar sees an object that is 50kph speed difference from your car, and you car is doing 50kph, it knows that the reflective object is stationary and probably some road infrastructure, houses etc. It therefore ignores it.

 

Any reflections that have a Doppler/speed difference that is not the same as the speed of your car, are moving. And therefore probably other cars. The system will react appropriately to them.

 

In the case of a reflection which is moving, but then slows down to become stationary, the car realises that this is a vehicle that has come to a stop.

 

So in summary, if vehicles that are travelling ahead and in range of your radar, come to a stop, the ACC will react appropriately and bring your car to a stop.

 

But if you come round a corner and encounter stationary traffic, or come up behind cars that are already stopped, the system will assume that they are fixed objects like houses etc and presume that the road curves before you get to them. So you have to brake yourself.

 

Obviously it is important to understand how the system works!

 

The other thing to bear in mind is that there is a deliberate limit on how hard the system can apply the brakes. This is to avoid a system glitch causing maximum braking which might create a rear end shunt. So sometimes, even when the system is correctly applying the brakes to avoid hitting the slowing vehicle in front, it might be necessary for you to push hard on the brake pedal. There is a ping and a big red symbol to tell you when to do this!

8 hours ago, JR RS said:

If it moves off, urs will follow.

That's wat ACC does.

If it moves off within 3 seconds ACC will autofollow (ACC Ready will be shown on dash).

After 3 seconds you need to tap the accelerator

57 minutes ago, Winston_Woof said:

If it moves off within 3 seconds ACC will autofollow (ACC Ready will be shown on dash).

After 3 seconds you need to tap the accelerator

Or you can pull on the ACC stalk after the 3 seconds.

I'm lazy, it's easier I find to tap the pedal

Does anyone else sometimes get this and the accompanying bong when driving on twisty country lanes?

The system must think I am about to drive straight on into the hedge or long grass / overgrown verges.

Up to now, luckily I have steered into the bend before it brakes for me! 
 

1 hour ago, Winston_Woof said:

If it moves off within 3 seconds ACC will autofollow (ACC Ready will be shown on dash).

After 3 seconds you need to tap the accelerator

For some reason I can't determine, mine will sometimes use the three seconds thing, but other times it says Ready forever, and however long the delay is, it will then auto follow. Other times it never says Ready at all and won't follow even after one second without pulling the lever.

 

I like the "will follow however long I wait for" behaviour best.

@crankcase mine rigidly sticks to the 3 seconds

1 hour ago, Shuggyboatsuperb said:

Does anyone else sometimes get this and the accompanying bong when driving on twisty country lanes?

The system must think I am about to drive straight on into the hedge or long grass / overgrown verges.

Up to now, luckily I have steered into the bend before it brakes for me! 
 

Not something I've personally encountered and I have mine set at "Early" warning

Edited 7 June, 20241 yr by Winston_Woof

20 hours ago, Winston_Woof said:

am I the only person thinking that emergency braking assistance is an emergency system and not something you should be relying on in traffic?

That's what the brake pedal is for.

FYI if you're talking about when you have ACC enabled (which will bring you to a stop if the vehicle you are following slows & stops) then the handbook explicitly states it doesn't stop for stationary objects. 

 

 

I am really sure that it worked for my car. Even in the traffic jam it stops and move into completaly stationary position and if the car in front of the car it moves if it happens in 3 seconds automatically, buffer to buffer.

 

My experience is if there is a car in front of me and stationary it brakes and stop completely.

 

I do not think that i am confused.

 

But, i will test this 2 situation as soon as possible and share the results.

 

Thanks to everyone who replied the topic.

46 minutes ago, enoktakenokta said:

 

 

I am really sure that it worked for my car. Even in the traffic jam it stops and move into completaly stationary position and if the car in front of the car it moves if it happens in 3 seconds automatically, buffer to buffer.

 

My experience is if there is a car in front of me and stationary it brakes and stop completely.

 

I do not think that i am confused.

 

But, i will test this 2 situation as soon as possible and share the results.

 

Thanks to everyone who replied the topic.

I was going from your original statement that "I noticed today that when the other cars stationary at the traffic light, my car does not brake automatically"


Which I read as "when I approach already stationary traffic but not following another car within ACC RADAR range then my vehicle does not stop" . This is correct. ACC will not bring you to a stop in this scenario and the handbook explicitly states that.

If however the scenario is " When following another car (within range of the ACC radar) and I am using ACC and the car in front slows to a stop my vehicle does not brake" then that is a different kettle of fish and may be indicative of a fault scenario,

On 07/06/2024 at 11:55, enoktakenokta said:

 

 

I am really sure that it worked for my car. Even in the traffic jam it stops and move into completaly stationary position and if the car in front of the car it moves if it happens in 3 seconds automatically, buffer to buffer.

 

My experience is if there is a car in front of me and stationary it brakes and stop completely.

 

I do not think that i am confused.

 

But, i will test this 2 situation as soon as possible and share the results.

 

Thanks to everyone who replied the topic.

 

I could not make the test that i thought because there needed 2 drivers and 2 cars and i could not find second driver to make the test.

 

But, yesterday without causing a danger for anybody i found an opportunity.

 

My speed was araund 30 km, acc was engaged, traffic lights were approximately 80-100 meters away, a car was stationary, car detected the other car, and acc started to make car speed decrease by means of auto braking. It was not a sudden and disturbing stop; and I have to say that everything in this case did not cause any danger or problem. Of course the speed was very low and i always took the precauitions and i was in a position that when needed i could take the control quickly.

 

Briefly, everything was as i supposed and the system operates perfectly.

 

P.S.: These are my experiences, so if you try this and there happens problem i do not take responsibility.