What exactly is data card code 258 (COLLIS.WARN. SYS. W/ ACTIVE BRAKE INTERV. FCW STOP)?

Discussion in 'General Discussion' started by wongl, Jul 14, 2019.

  1. wongl

    wongl Hardcore MB Enthusiast

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    Just acquired a 2016 W246 for my daughter and from the Data Card I noticed that this car has code 258 (
    258 COLLIS.WARN. SYS. W/ ACTIVE BRAKE INTERV. FCW STOP).

    Whilst driving on the motorway home, I noticed that a red triangle warning light on the dash when I got to close to the car in front, but the car didn't brake for me. So what exactly is code 258 and how is is a collision warning system with active brake?
     
  2. JDPEClassUK

    JDPEClassUK Active Member

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    If you had been gaining on the car in front and did not intervene by braking, the active brake would have done it for you. I would never rely on it as it is a bit last minute and designed to intervene if you don’t react quickly enough


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    Ted and wongl like this.
  3. OP
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    wongl

    wongl Hardcore MB Enthusiast

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    I see, it I did not take any actions, the active brake feature would have activated the braking for me.
     
  4. zipdip

    zipdip Hardcore MB Enthusiast

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    Well it one of those systems it is best not to try out just in case,but hey fill free to give it a whirl on the Causeway.
     
  5. Pontoneer

    Pontoneer MB Club Veteran

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    Try it in a demonstrator , or hire car ...
     
  6. BMF

    BMF Hardcore MB Enthusiast

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    I have gotten too close to hedgerows recently and it has activated, you should get an audible warning also, but it scared the bejesus out of us the first time.
     
  7. OP
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    wongl

    wongl Hardcore MB Enthusiast

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    Thanks everyone who contributed to this. Looks like the system does not brake until the driver activates the brakes.
     
  8. flowrider99

    flowrider99 Hardcore MB Enthusiast

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    No, the car will automatically brake if the driver doesn't if you get to close to the car in front.
     
  9. fredfox

    fredfox New Member

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    I've had it active twice, the first time I was about to brake and the bloody card started beeping, I panicked, looked around for what the bleeping was and it slammed the brakes on before I could. Frightened the life out of me - I didn't know the car had it (handover was crap). The 2nd time it was a typical motorway moment of everyone hitting the brakes, the car did it a fraction of a second before me.

    It does work, but I wouldn't rely on it and I certainly would try and test it by driving close to another car!
     
  10. OP
    OP
    wongl

    wongl Hardcore MB Enthusiast

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    Thanks everyone for confirming with your personal experiences, and good to know that the brakes will be activated automatically.

    The information available is confusing - for example the NCAP URL provided clearly states that the system does NOT activate the brakes until the driver does, at which point it will brake assist (and apply more pressure if necessary to stop the car in time). The Online owner's manual is useless on this point - almost deliberately vague so as to avoid any litigation perhaps?
     
  11. BMF

    BMF Hardcore MB Enthusiast

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    I think the emergency brake assist And the collision avoidance system are separate systems, the first is a system that when the driver applies the brakes in an emergency situation the system detects this and applies braking assistance, the collision avoidance system monitors the road ahead and if it detects an obstacle and the braking system is not activated by the driver in time the system bleeps to attract the drivers attention and applies the braking system to try and avoid a collision. I will stand to be corrected but this is my understanding of these two systems.
     

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