I have 07 S550 with Distronic Plus and intermittently the DistronicPlus will just shut off for no reason. Had the dealer look a few times and got he infamous statement of " there is no codes". The last statement from them was "it is a enhanced cruise control and can shut down if it does not like the things around it". Now Im not an electronic engineer but Im not sure the system is just supposed to be intermittent. Does anyone have any comments or experiences to help me deal with the service dept. i would appreciate it. I use the system alot with my family in the car and I don't want to use it if it can just shut off if it wants. It has to be something in the system because the park assist will just shut down whenever it feel like it as well. (the car has alot of feelings according to the dealer)
Thanks in advance,

 

take it to a diff. dlr. also take the foreman with u for a drive and show him exactly when it happens. hope it helps.

 

There are situations where Distronic Plus will shut off. Aka 90 degree turns where it loses track of the car in front of it is the most common one I see. You'll hear a beep. In this case, the car is being safe and saying, the radar cannot track the car in front, so it's safer if the driver takes over.

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

 

I guess I've never used Distronic Plus at 90 degree turns and have not seen that message.

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 had a few situations where it will apply the brakes and then give a warning and shut off. It has occurred when you are going through a moderate curve in the road and the car in front abruptly leaves the lane you are in. My guess it throws off the system and wants you to take control. I frankly prefer it to play it safe.

 

This sounds like a case where the driver should have been using brakes and if the driver had been using brakes, any car would disable CC (be it Distronic Plus or not).

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

 

Nothing is bulletproof.
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).

 

Is that because of the vertical beam width of the Distronic radar not being sufficient?

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.

 

The scenario I described involved a car leaving the lane I was in. Normally that is not a reason to brake; I think the system just gets confused and applies the brake as a precaution. I have also had very loud and alarming warning go off in slow driving telling me parktronic was unavailable only to then turn back on 2 seconds later. This has happened 2-3 times. The only reason I mention it is because the system relies on the same sensor behind the front grill. I would imagine it is getting some interference from another source.

 

I did not read carefully then, I thought the case was a car cutting in. I've had cars leaving the lane in front of me countless times and never observed Distronic Plus getting confused about that. Really strange if the car brakes in your case in this scenario, the radar system can anyway detect that the car changes lanes. Could your radar need calibration?

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.

 

It doesn't happen whenever a car changes lanes, only under one particular maneuver. If I am in the middle lane in a moderate corner and the car in front moves to the inside lane (basically making a sharper corner) the system gets confused. The system seems to read your angle of steering to see where you are headed, since in a corner the car directly in front of your car might actually be in the next lane (due to the bend in the road). It must read your angle and say 'no, I need to look at this other car because the lane is turning to the left and this car directly in front is really in the right lane' (or something to that effect, the car probably says this to itself in german, not english ). 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 guess you are considering the cruise control feature alone, of course the main radar would not see behind the car and rear bumpers need radars for Parking Assist (Parktronic).

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).

 

I meant to say for the front of the car, I do have sensors in the rear bumper, but none in the front...

 

Can I have your VIN? How do you know you would not have additional radar sensors behind the front bumper? There is no such W/V221 with Distronic Plus that would not have those. There is an option with Distronic (no Plus) but then the car would have traditional acoustic/visible Parktronic sensors front and rear.

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.

 

There's an issue with a battery. Have it replaced - it's in service bulletins if you check out the sticky thread.

 

I don't know if there are any behind the front bumper, I assumed if they are not exposed (like the rear), then the car did not have them in front. Frankly, if the sensors can be hidden behind the bumper cover, then they should make all bumpers that way. I'll send you a PM later...

 

IIRC, DistPlus in Europe entailed bulletholes in bumpers but not in US, until MY10

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

 

This is not correct. Distronic Plus in Europe is the same as Distronic Plus in the US. You must be confused from the options we have in Europe (and the options we lack being standard).

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.

 

Now that you mention the MY2010 changes I figured out the face lift follows the W212 design. Even if the car comes with Distronic Plus, it still has ultrasound sensors too. But it also has two of those hidden bumper radars!

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).

 

OK, I guess I forgot which car I was thinking of, my S550 does NOT have rear bumper protruding sensors- they must be mounted behind the bumper. Whatever- All I know is the thingy goes beepy...

 

This is obvious for a (US) W221 with Distronic Plus. But the main discussion was about similar hidden bumper radars at the front. I bet this car has four of those at the front, hidden in the bumper.