Hello everyone,

Recently I have bought a 2014 facelifted A8, which had coded ACC sensors, so I had to buy second hand ones, then they were calibrated and finally now I have ACC, which works perfectly in traffic, but I am not sure that the Braking guard function works, it is turned on in the menu. When I drive closer to vehicles, I don’t get the red warning that I am driving closer to the vehicle ahead, which I should get. Therefore I am not sure that my Braking Guard is functioning right now, although I don’t have a warning that it isn’t working, and also the ACC works brilliantly and makes the car to come to a full stop, like it should. So I am a bit confused, does anybody know if thats how it is, before I go the the workshop again.
cheers

 

If the vehicle in front of you is matching your speed or going a bit faster then I would not expect brake guard to warn or engage. However, if the vehicle is slower than your pace you should get the warning. Have you made sure the feature is turned on in the driver assist menu of the MMI?

 

Yes, I have checked in the MMI, and it is turned on, and the early warning is also on. But your point does make sense, maybe the vehicle in front has to travel slower than you, in order for the braking guard to show a warning. I will do a longer test drive today to see if I can trigger it, of course without crashing

 

Braking guard does not give audible warning unless it needs to. You need to be in a situation where you are very quickly approaching a vehicle moving slower than you.

The best way I can see to test functionality- while remaining fairly safe- would be the following scenario:

you on a road with multiple lanes traveling in the same direction. You are following a car with it’s right hand turn signal on and you both are in the right hand lane and you are following at a distance of several car lengths but close enough that the ACC knows the car is there and importantly, there is no car to the left of you. The car you are following begins to slow down to make it’s right-hand turn. You continue at your current speed in anticipation for the car to clear your path when it completes it’s turn. Your braking guard is not intelligent enough to know the car is turning and will clear your path in time for you to pass without slowing down, braking guard only sees that you are approaching much too quickly and if you get close enough to the turning car and are going fast enough you should get the audible alarm. If you are even closer (hopefully) braking guard will intervene and you will know it is functioning.

The importance of having multiple lanes traveling in the same direction and no one to the left of you means you can relatively safely approach a turning car at speed to test braking while having a safe lane to exit to if the car in front does not turn in time.

This has happened to me naturally a couple times where the car in front is almost done with its turn and I know it will be out of the way by the time I reach so I maintain speed. Braking Guard doesn’t know so I get a ride awakening and it stands on the brakes. I know now I need to either change lanes or slow down so braking guard doesn’t intervene.

This will be easier to test with a friend, just approach them (with them still moving as ACC cannot ‘see’ stationary objects) at a quick rate of speed and change lanes kind of late.

I hope all this makes sense. You can also look for the red icon that flashes when you follow someone too closely for an extended period. (Green ACC light in speedometer dial flashes red)

 

I have tried on the motorway to quickly accelerate to the back of the car in front of me, which stressed a bit the driver, hence he accelerated a bit when he saw me tailgate him rapidly, and the car didn’t respond at all. The distance icon didn’t flash red, or it didn’t warn me in any way. I think that in that situation it should warn me in some way, I have also tried to change lanes rapidly when there is a car close to me in front, and again no effect. Very weird. I don’t know if thats how it works, because my ACC works perfectly and makes the car come to a complete stop. I thought the 2 functions work together, and if one of them has a problem the other wouldn’t work as well, is that the case?

 

Braking Guard does not work in the ways you attempted.

Flashing red ACC icon in speedometer only appears when:
-you follow too closely for a ‘long time’ (that’s how Audi defines)

Warning in driver’s information screen and audible warning only appears when:
- you abruptly approach a recognized vehicle
-a recognized vehicle abruptly pulls out in front of you

Warning screen and beep with automatic braking only happen when
-an accident may only be avoided by sharp braking
-an accident is imminent

Unless your test follows these circumstances then braking guard won’t activate

 

Try to ram into a cardboard box. That’s how they test it when I have seen it.

 

I have thought about that, could give it a try soon. Although I presume that it works, hence there isn’t a warning that it isn’t functioning. And from what the fellow users have said, it only triggers it when the situation is more critical than normal. And my ACC works perfectly as well, probably time will tell if this function is working properly.

 

Braking guard, like ACC, likely will not pick up a stationary object. Also Audi says it likely won’t pick up a motorcycle so a cardboard box will probably go undetected

 

Aren’t ACC and Braking guard completely connected to each other ? , since when my sensors weren’t connected it said that “ACC and Braking guard aren’t functioning” With that in mind, does that mean that when one of the two isn’t functioning the other also will give a fault?