DISTONIC PLUS ISSUES
Thanks in advance,


Thanks in advance,
This is normal. If you are losing Distronic Plus in regular straight-line follow situations, then that may not be normal.

This is normal. If you are losing Distronic Plus in regular straight-line follow situations, then that may not be normal.
It should not turn off if it sees something strange around, it might give a warning (like if it heats up and when too much snow on the grill disables proper operation) but one would always see a message.
Another case where Distrconic Plus turns itself off is when driving close to radio astronomy stations, but this would always happen at the same place if one lives close to such a place.

I have not faced a similar traffic scenario but I agree, in a case like this Distronic should switch itself off.




Relying on Dist+ too much = major accident waiting to happen.
Same thing happens to me on occasion as described by emilner.
I have to describe/share one scenario, a dangerous one, where Dist+ causes the accident.
One of the roads have the hill, driving about 50mph, right over hill 100 yards or so there is intersection with traffic lights. If the cars are there (red light), Dist+ doesn't react at all, doesn't catch the cars in front at all. I tested it few times and I guess the beam "gets confused" every time (only on that hill).
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Relying on Dist+ too much = major accident waiting to happen.
Same thing happens to me on occasion as described by emilner.
I have to describe/share one scenario, a dangerous one, where Dist+ causes the accident.
One of the roads have the hill, driving about 50mph, right over hill 100 yards or so there is intersection with traffic lights. If the cars are there (red light), Dist+ doesn't react at all, doesn't catch the cars in front at all. I tested it few times and I guess the beam "gets confused" every time (only on that hill).
It is clear that Distronic Plus is a driving aid, the driver has to maintain control over traffic scenarios. But I understood that the issue the OP had was about Distronic Plus switching itself off, it would be interesting to know if this happened because of a traffic scenario similar to emilner explained or if it really is some kind of a malfunction.
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I have not faced a similar traffic scenario but I agree, in a case like this Distronic should switch itself off.

Parktronic actually works with the radars behind the bumpers, not with the main radar (Distronic Plus is using both, the bumper radars mainly when slowing down to standstill).
I would have the Distronic Plus control units flashed for new SW, might help.
). When a car moves further into the corner (changing lanes) than your angle the system probably loses it's target and sees you veering out of your lane or something. I know, it's a lot easier to describe on paper.I am under the impression that cars that come with Distronic + do not have other sensors in the bumpers; they rely on the large main sensor in the grill instead.

I assume you are aware of the bumper radars at the front, early model years had four at the front, two at the rear. These are used for cruise control too, but only at short distances. I'm not sure about your scenario, the car could be far enough to be followed only by the main radar.
WIS would have a reasonable description about the system for anyone interested about details. Likely no exact explanation for the case you describe but I understand you assume Distronic Plus considers there may be a danger in which case switching CC off would be reasonable. Applying brakes sounds at least inconvenient but I guess it thinks "better safe than sorry" (what ever it is in German).

This detail does not make any difference to the actual discussion here and the misbehaviour you have observed but I would just like to have the technical issues cleared.
This detail does not make any difference to the actual discussion here and the misbehaviour you have observed but I would just like to have the technical issues cleared.
For MY10, DistPlus system was updated in terms of range, active functions, etc and bulletholes are included (even in US) for the ParkAssist function which uses sonar (IMO, an utterly worthless function even in urban parallel parking...any space that tight means the rusty cars adjacent will scrape one's new MB anyway)
Refuse to ever use DistPlus cruise ctrl function, though I highly value the active safety element of the radars and BrakeAssistPlus...I prefer being fully in control of throttle/brakes/steering of my car and aware of my surroundings...cruise tends to lull one and one's feet and hands are in an inalert position for emergent maneuvers, where a sec or two of delay can be catastrophic
And in urban traffic (either fwys or surface streets) much of active safety is monitoring one's rear view mirror and judging risk of nearby drivers...and adjusting speed, following dist and lane position based on POS cars following one, as one's superior brakes merely entail being rear-ended if one doesn't apply human intelligence/judgment that no computer can (yet) offer
Huge diffce in risks cruising on a fwy at 80+MPH in busy traffic w/a new S65 in one's rear-view mirror than a more typical 10yo SUV/Toyo/Honda w/an inept, inattentive driver and no brakes/handling...they don't hand out certain cars/SUVs to just anyone

There is (or at least used to be) a standard Parktronic option also for the V221. Actually the W221 didn't have any Parktronic standard (for smaller engines at least). This basic Parktronic is exactly as we have seen on other MBs like W211 before. Front and rear have visible ultrasound based sensors.
Distronic Plus comes with the big main radar at the front plus two smaller radars (operating at a different frequency too) plus four in the front bumper. These bumper radars are all hidden because the radar can see through the bumper cover, just like the main one can see through the plastic shield at the grill. The four front bumper radars were actually cost optimised to two at some point (unless I'm mistaken with the W212 approach that combines bumper radars and acoustic sensors with the main radar of course, I did not check the latest 221 design).
There is a third option for the 221 which is Distronic (no Plus). This is like the W220 Distronic and is intended for markets where the bumper radars are not allowed because of their operating frequency. In this case both front and rear bumpers have visible acoustic sensors. But this distronic is limited to speeds above 30 km/h and cannot bring the car to standstill when following a car in front slowing down.

In my opinion the traditional acoustic Parktronic is more accurate at close proximity in different scenarios. I believe this is not an issue in the US traffic and your parking lots but it makes a difference in Europe and elsewhere with less room for parking.
PS. I don't take any position on how useful each feature is, this is pretty much a personal view (a significant number of studies exist anyway), I just wanted to get the technical topics cleared (for myself/for others).




