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Discussion Starter #1
Hello everyone, I've been driving my metris van for 2 1/2 months, I drive about 800 miles a week mostly freeways, everything works on my van except the collision prevention assist feature.
I haven't heard the warning beep or seen the red indicator light come on on situations when there is a sudden stop (L.A traffic) or I'm getting too close to other cars. The icon is there all the time and the red triangle light turns on for a second when I switch the ignition to the on position. Do this only works on extreme situations, like one second before impact?
I would like to hear your experience before I take it to the dealership.
 

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My collision avoidance system sometimes beeps at a particular mailbox that is directly in front of me as it doesn't know the road turns just before the mailbox.
 

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It generally only happens when it becomes apparent you aren't doing your job as a driver. Or a mailbox with a reflector is in the wrong place.

I can go a week or two without it going off and I am a chronic massive tailgater.
 

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I agree with Green. At times it can be pretty **** 'smart' (ie. it never seems to go off, such as your case) or slightly 'dumb' (ie. the mailbox example). About the 2nd week I had my MC I was going about 35mph on 2-lane urban road and just daydream for a moment looking near the new instrument cluster when I heard, THE BEEPS! Its very distinctive (which is good) and I hit the brake, like the feature says, I did somewhat feel there was added brake pressure. While I wouldn't say I dodged a close one, it could have been a fender bender...so I can already chalk it up as an option that already paid for itself.

Some false alarms have included driving into a parking lot area and someone makes a wide turn coming out of the parking lot area lanes. Driving in 35-45mph zone in right lane and someone making a right turn and you try to 'time' slowing down just enough to not have to come to a near complete stop. Other than that and a couple other instances, it's been a rock solid featureset.
 

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Discussion Starter #5
Thanks for the reply, I think the radar needs to be calibrated, I found this on a youtube metris ad video. It shows max. distance 213 ft.:confused:
 

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Max distance is 213 feet. If you are going 70 towards a fully stopped car at that distance it will activate. Not only that, if you react fast enough and aren't loaded, the van will stop at that speed and that distance quite easily. I mean it will be a scary event and all, but it should stop (70-0 was recorded at 190 ft, giving you about a quarter second to react), the brake assist and prefill will drop the anchors, and after you are done cleaning bodily fluids off your seat, you will forever recalibrate your sense of how fast a 5000lb van can stop.

If you are going 40 towards a stopped car it will not. You have plenty of time to react. You don't want it to beep at you any more than needed, lest you learn to ignore the beeps, or scare you needlessly. In fact the primary benefit of the system, in my opinion, is it's abiltity to *extend* stopping distance, because it is programmed to use the maximum amount of distance to stop, so as to stop your car without rear ending the person in front- while giving the person in back of you maximum time to react and not rear end you.

I suggest taking your van to an abandoned spot and getting a feel for the capabilities of its braking system. Don't worry, you won't break it and it won't skid. If it does, then yes, take it to your dealer, there is something wrong with it. American trucks have been dangerously under braked since time immemorial and Asian products generally ignore safety entirely.
 

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Thanks for the reply, I think the radar needs to be calibrated, I found this on a youtube metris ad video. It shows max. distance 213 ft.:confused:
So, did you ever resolve whether or not it's working? Mine behaves the same way. I drove an E-class in Europe and saw the orange triangle a few times, but never once in the Metris.

Where is the radar antenna located? I can't see anything obvious in the grille area.
 

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Discussion Starter #9
I don't have time to take it to dealership, I will mention when I take my van for the First maintanance service, but still no warning indication yet.
 

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I presume you haven't crashed into anything, or activated the brake assist yet, either.

You'd know if you activated brake assist. The van suddenly feels like it's braking harder than you intend it to. That's not part of the CPA, by the way. If you aren't braking hard enough to incur ABS and brake assist on a dry road, it wasn't such a stop that CPA would have kicked in anyway.
 

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Maybe I'm being more cautious with my new baby, but I'd think I would have seen that triangle at least once now in two months. It was pretty easy to get it to come on in the E-class the first day I had it.

Where exactly is the antenna? I looked all over the place and near the fog light. Is it completely hidden by the bumper plastic with no sign whatsoever that it's behind? The OM has a section for cleaning all sensors on the front bumper but it only looks like there is a strip of area extending between the six parktronic sensors that it is referencing. Van is clean already.

I may have to call MB and ask. Too bad I was just in there for Service A. After re-reading the OM the other day, I realized the van also has the same warnings like the E-class, and if I don't see it when I'm tailgating, I probably won't have brake assist if I need it since those two rely on the same hardware.

Thanks!
 

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I never get visual warnings when I tailgate, and I'm a pretty prolific tailgater. I have had the system go off in circumstances when it was actually needed, and it worked fine.

That being said, if you are convinced it isn't working, despite what it's self diagnostic says, take it in.
 

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I think my system may actually be working after all. The warning light and audible alert went off today with a false positive just before going around a corner with a forested median and sign in the middle of the street. Perhaps it works differently than what my 2016 E220 rental had, which would immediately warn me if I was following too close.

I re-read the Metris Equipment Book and it reads "A red triangular warning lamp appears in the instrument cluster when the distance to the vehicle in front falls below the minimum for several seconds. If the distance continues to decrease rapidly an intermittent warning is also sounded. ". I suppose the key word is several seconds. The owner's manual also says "With the help of the radar sensor sys- tem, the distance warning function can detect obstacles that are in the path of your vehicle for an extended period of time. If the distance warn- ing function detects that there is a risk of a col- lision, you will be warned visually and, where necessary, acoustically.". Also extended period of time sounds like it won't light up unless the situation lingers. Sounds like I'm OK.
 

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My Collision Prevention Assist warning most often goes off if a car in front of me slows suddenly to make a left turn. And NO I do not tailgate. I hate tailgaters and I am not a tailgater.

My CPA warning also sometimes goes off as I approach this bridge in Kent WA.
 

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Discussion Starter #15
It looks like your sensors are more sensitive than others, mine finally went off yesterday during stop and go Traffic I heard the 2 beeps and the red triangle indicator light came on for half a second.
 

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In general, you do NOT want to hear the beeping or see a red triangle. Honestly, the triangle can pop up, flash and disappear faster than most people will see it...because they are focused on what they are about to hit. The audible warning and flashing should only alert when the van 'thinks' that an accident is imminent. It is picking up the distance to an object in front of you, how fast you are closing on it, whether or not your foot is on the gas/braking/coming off the gas/etc...it is alerting you to take action to prevent the action it has calculated as imminent IF 'you continue exactly how you are now' (ie foot still on throttle, not braking at all, etc). It's crazy, but the system is somewhat difficult to 'trick.' If it senses your foot come off the gas when a car begins to brake in front of you, it senses the distance closing, but ALSO knows you are decelerating because your foot is no longer on the gas. That being said, if you continue to coast, and the car in front has come to a complete stop, and you never touch the brake, you'll get the alert. At that point, if you simply tap the brake ever so lightly, but it's not enough to stop the van before hitting the car in front of you, you'll feel the brake pedal sort of 'pull' into the floor beneath your foot to assist in braking...
 

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I get two beeps at what seems random times. Never have I felt the break assist kick in. Furthermore I have nearly hit the car in front of me and there was no help whatsoever from the vehicle.
 

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Mine has gone off randomly about five times now but it won't do anything unless you tap the brake and I was always on the throttle at those times. Did the warning alert come on when you almost hit the car?
 

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They monitor the distance from a vehicle ahead giving warning in case of danger and optimise brake speed depending on the distance.
 
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