Can someone tell me exactly how this works?
 

258 COLLIS.WARN. SYS. W/ ACTIVE BRAKE INTERV. FCW STOP - from my data card.

I googled it and not much on this. I read the manual 3 times and can't find clarity. My local MB dealer is also clueless.

Ok I'll bite......

It's a radar activated warning system for people in your blind spot, aka the red arrow lights on your side mirror and the car beeps if you turn into a lane and there is something there, if you get to close to something when braking it will brake harder so you don't hit it...

Blind spot / lane tracking system is different.

its a forward collision warning system, if you wanna see how it works, and I don't recommend this especially if you have traffic behind you, simply drive up to a car at a high rate of speed without braking.

the video below is for audi's, I don't know at what speeds Mercs work, but the principle is the same

Do you have distronic?

If the car senses you are going to run into something it warns you and then applies the brakes to stop you. There are a series of quick beeps when this happens. I think after the 3rd beep it applies 40% brakes on its own followed by 100% if you brake or it hits the 4th beep unless the situation has corrected itself.

https://www.mbusa.com/mercedes/benz/safety#module-1

Collision Warning System with Active Brake Intervention (Forward Collision Warning - Stop)...that's my guess. On my 2014 E350 I do not have blind spot monitoring (side mirrors w/ warning lights) or lane tracking/guidance, nor do I have adaptive/distronic cruise control. But I do have forward collision warning and braking...it beeps when it sees something you're approaching, and will brake for you if it thinks a forward collision is imminent.

I do not have distronic but I do have BLIS and lane tracking. The issue is I don't think my forward collision is working properly. I have tried a few different ways to set it off but to no avail. The dealer said it's not giving them a code... I think I'll need to hear from MB directly on this.

Directly from MBUSA
 

Dear Steve:

Thanks for your email to the Customer Assistance Center at Mercedes-Benz USA.

It might be helpful to know that 258 COLLIS.WARN. SYS. W/ ACTIVE BRAKE INTERV. FCW STOP refers to the safety feature called Collision Prevention Assist. This feature consists of the distance warning function and adaptive Brake Assist. Should you approach an obstacle and Adaptive Brake Assist has detected a risk of collision, Adaptive Brake Assist calculates the braking force necessary to avoid a rear-end collision. Should you apply the brakes vigorously, Adaptive Brake Assist will automatically increase the braking force to a level suitable for the traffic conditions. For more information on this system as well as a video demonstration, please visit: mbusa.com- Collision Prevention Assist

We hope this information helps and wish you many miles of safe, pleasant driving.

Kind regards,

Olivia
Mercedes-Benz USA
(800) 367-6372

Fosterelli- be careful. If you don't have distronic, your car will NOT brake for you. It simply warns and judging by how you brake - (you know the panic breaking we all have done like when backing up when you thought it was clear or when you didn't brake fast enoigh on the highway). Adaptive brake Assit detects that and brakes really hard and all the way for you. The car "jerks"/brakes hard. That's pretty much it. Again just don't want to give u a false sense of security that without distronic that your car would still brake for you. You still ned to initiate the braking urself.

In terms of the OP thephantom's question, mine is similarly equipped. I don't know how to set mine off, but a warning red triangle in the instrument cluster blink and a warning beep sounds occasionally - false alarm in situation where it thinks I am getting too close to something that my speed and the object ahead may be a problem. Each time it has been a false alarm - so I don't have a good data point for u. I may play with it today to see if I can set if off... One situation I think can be if I am approach a curve (curve need to have a median) and my steering wheel is heading to it, this should set it off...
I don't want to try to ram my garage door to see if it set it off after I ram through it :-)

That actually makes sense. I can't get the warning lamp or sound to activate, no matter how hard I've tried. I even went on a ride with a MB mechanic to try to set it off and I think he may have peed his pants since I was rapidly approaching the car in front of us. He agreed that the warning should have gone off. So in other words, I am not receiving any warnings, so I would also think the brakes are not "braking" for me when needed.

Do this!
 

Can you get some large refridgerator size cardboard boxes? Cut them up and make a fake wall or something. Prop the cardboard up in your street or an empty parking lot in a way when you crash into it, it just falls down and u drive over it or something. See if ur car detects it. Someone mentioned to use foam blocks. Where would you find foam blocks that can make into a fake wall? I guess at SAMs club for all those cheap styrofoam coolers and ur copied stack up up?

I'll look into it. Thanks!

The warning beep can be easily set off while in traffic and if the car ahead of you on your left lane starts slowing down / braking (such as to make a left turn into an alley).
The roads in our area have a center lane precisely for slowing down and making left turns. Most of the time I hear the warning beeps when I pass through here. I was perplexed initially thinking that the beep was related to some GPS location. Later on I narrowed it down to the car in front of me braking and shifting into the left lane.

Got to post of video of this too!

Collision Prevention Assist Plus Does Break For You
 

I'm certainly no MB expert, but I don't think that you have to have Distronic for the car to brake automatically if you have "Collision Prevention Assist Plus". Per the below video, it will brake for you automatically if you are traveling at a speed up to 65 mph (too bad if you are going 70 mph :-( . Sounds like Distronic is better as it will brake up to 100mph (or something like that, I forget what the video actually said).


If I am wrong, please let me know. I do want to know if my car will brake for me if I am not paying attention. This leads me to believe that it will.

Hi,

my 2014 E350 lists the following on it build sheet: "SA code: 258; Description: COLLIS.WARN. SYS. W/ ACTIVE BRAKE INTERV. FCW STOP"

Is that the "collision assist plus" system listed in the MB video above? If not, how does this 258 system work? I imagine it would apply the brakes under certain conditions, but I do not know exactly which conditions.

I have to agree with you strefry...my car has DEFINITELY braked for me, twice actually. Once it saved me from an accident, and the other time I think I would've still been okay and stopped in time. And my build sheet does not have Distronic, nor does my Comand Center have any adjustments for it.

My understanding is the Distronic is a feature to pace the vehicle in front of you, while in cruise control - and the following distance (at least on our Sienna and MDX) is adjustable. If the vehicle in front of you slows, your vehicle automatically keeps the preset following distance the same - and will stop for you if necessary.

The collision warning with active braking is just what it says...warns you of immediate frontal collision dangers (audible beep), and if necessary, actively brakes the vehicle to help prevent this collision. And my vehicle definitely does this (thankfully)!

We have the 258 option on my wife's ML350, the dealer had no idea how it works as to rather if the car will brake for you or not. It seems like the same confusion exist in this forum. Mercedes really should provide more information for their customers concerning options and features.

Agreed- if you have "Collision Prevention Assist Plus" your car will brake for you just like the video.


I believe my car only has "collision Prevention Assist" - no Plus. My car only warns and does a series prep work to help me brake faster and harder to hopefully prevent a collision. There is another video on YouTube that is Collision Prevention Assist only. I believe that's what I have.

From this video, one would think Collision Prevention Assist will brake for you:
This video is on a 15 B-Class and it seems to brake automatically also:
This one says it'll only work between 20mph to 40mph:
Still confused!!:smash::smash::beat::beat:

I think the key word in these 3 videos vs the one that was posted about "plus" is autonomous.

So yes, they all "brake for you" only that Assist PLUS would "initiate the braking" in the event that you don't.

The ones without the plus would still assist, but you need to touch the pedal for the Brake assist to kick in.


Clear as mud? I know it totally sounds confusing. If we ask the MB dealers "des my car brake for me?" Technically it's a yes. But we should ask"does my car brake for me in the event that I don't have my foot on the pedal to initiate the braking?" Would like to see if they can address that on option 258...

Ok. I spoke to Mercedes itself and option 258 is "Collision Prevention Assist", not "Collision Prevention Assist Plus".

"Collision Prevention Assist" monitors obstacles in front of you when driving above 4 mph and will warn you with beeps and the flashing red triangular automobile icon in the center top your left (fuel & water temp.) gauge if the car thinks you will crash into the obstacle it noticed if you continue at the same speed and and in the same direction. It will not brake for you. However, if you hit the brakes, the car will calculate the brake force necessary to avoid the collision and apply that force regardless of how hard you hit the brakes.

"Collision Prevention Assist Plus" will do the same as the above but will brake for you regardless of whether you hit the brakes or not. This option only comes with "Distronic". I do not know if it depends on both or either the hardware and software installed with Distronic, or if "Collision Prevention Assist Plus"" is just bundled with Distronic for economic reasons.

I wonder what the reason is because both "Collision Prevention Assist" and "Collision Prevention Assist Plus" have to rely on radar information, leading me to believe, adding "Plus" to "Collision Prevention Assist" would be a software matter only.

That makes sense, and thanks for sharing. I don't get beeps no matter how rapidly I am closing in on the car in front of me. I'll have to get this looked at again. On a similar note, am I suppose to get beeping warning with fast flashing red lights on the side mirror if I have my directional signal on going towards the warning side? I only get the flashing warning.

For collision waring (red triangle in the left circle gauge, fuel & oil level one) should flash and beep.

For blind spot warning (red triangle in the side view mirrors). if signal is activated and in that direction a car is in the blind spot, the triangle in the mirror flashes and the car beeps also.

in both cases, you should hear audio beeps.

So I had the car at the dealer over night and they tried to troubleshoot the no beeping issue. They tried everything under the sun and finally fixed it by reflashing the instrument cluster software. Now I hear beeps when I first start the car and when I use my directional signal when the light is red on the mirror. However, I have not been able to get the Collision warning to go off... yet.

I am right there with you, in that my CPA system seems inoperable. I have not had it work, and I am an aggressive driver.

Did you ever get resolution?