Adaptive Cruise (ACC) and M6 Roadworks Contraflow lane

[kurienp]

Ok, this is the third time this has happened and this time I purposely drove in the contraflow lane on the M6 roadworks near Stoke-on-trent (coming down south from the lakes). Just about a mile into the contraflow lane, If the van is on ACC, it throws an error - ACC not available. Can someone else try this. Any idea why does it do so?

 

[Loz]

Metal barriers?

 

[Lightning]

Electromagnetic interference from something next to or in the road?

 

[kurienp]

Metal barriers?

I thought so ... but just that should not impact. Have driven past many metal barriers on the M4 roadworks, but have not had any issues. The difference though here is - metal on one side an concrete on the other ... but then logically the ACC should be able to manage that.

Electromagnetic interference from something next to or in the road?

I guess so and that is what my first thought was ... but what can it be?

Anyone who goes past with ACC, do try and see if that happens to you or not will be interesting to see.

 

[Lightning]

I thought so ... but just that should not impact. Have driven past many metal barriers on the M4 roadworks, but have not had any issues. The difference though here is - metal on one side an concrete on the other ... but then logically the ACC should be able to manage that.



I guess so and that is what my first thought was ... but what can it be?

Anyone who goes past with ACC, do try and see if that happens to you or not will be interesting to see.

Anything powered can potentially be faulty and radiate at high levels. Alternatively it could be a manufacturing fault specific to your van causing it to be particularly susceptible. It can be tricky to track down.This is part of what I do for a living in aerospace engineering.

 

[Loz]

The radar units have an error threshold and those metal barriers cause a lot of scatter. As do very clean reflective traffic cones.

 

[Amarillo]

I had a similar experience twice at the same bend on the same stretch of road in Romania. I emailed VW and they said something to the effect of, nearby railway lines can have this effect. There was a bridge over a river where this happened but no railway line.

My initial thought was that it was police speed radar interference.

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[Bluebird]

I have ACC on my golf and drove that stretch of the M6 last week. ACC was on throughout the roadworks and I had no issues.

 

[kurienp]

I have ACC on my golf and drove that stretch of the M6 last week. ACC was on throughout the roadworks and I had no issues.

@Juste , interesting. Did you take the contraflow lane on that stretch?

 

[soulstyledevon]

No issues with the reliable standard cruise

 

[Bluebird]

@Juste , interesting. Did you take the contraflow lane on that stretch?

To be honest I’m not 100% sure, the drive was without issue so my recollection of the finer detail is vague. Next time I head down south I will try the contra flow with ACC on. In the current climate I’m not sure when that will be ‍

 

[GrumpyGranddad]

To be honest I’m not 100% sure, the drive was without issue so my recollection of the finer detail is vague. Next time I head down south I will try the contra flow with ACC on. In the current climate I’m not sure when that will be ‍

Maybe the average speed cameras? They’d be facing the front of your vehicle rather than the rear as normal.

 

[Nolan]

Maybe the average speed cameras? They’d be facing the front of your vehicle rather than the rear as normal.

Back when we used to go to work I'd use my ACC though the entire stretch of roadworks on the M27 which has lots of Average Speed Cams so they don't normally cause an issue.

I guess it's best that it disables itself if it's unsure, I'm sure I had an error once and had to clean the sensor square in the bumper but it was when the van was quite new and hasn't happened since.

 

[Lightning]

Another possibility is that your sensor alignment is slightly out, resulting in a failure where it would normally be ok.

 

[kurienp]

Maybe the average speed cameras? They’d be facing the front of your vehicle rather than the rear as normal.

Interesting you mention that. Did not notice it though. Next time. I just think they are rear facing though. Will check.

Another possibility is that your sensor alignment is slightly out, resulting in a failure where it would normally be ok.

Quite possible. Will get it checked next time it is in for a service, which may be a year away Normally, it works fine. It is only this particular stretch where it has caused me issues ... in the last 10,000 miles.

 

[Loz]

It won’t be the speed cameras as these are purely passive.

 

[coopersd]

I’ve had three occasions where the EPC error illuminates, each time I was driving on the motorway (but nowhere near the contra flow). On each occasion the EPC light has been accompanied by a message stating that ACC isn’t available and the engine has gone into a reduced power mode. The problem has to the best of my recall only occurred during wet weather. I’ve had to pull over and turn the ignition off to allow the EPC to reset.
The dealer was unable to replicate or identify the cause, but thought it could have been due to water spray from vehicles in front.

 

[Calivelle]

I drive this stretch too and have had the same issue when in the contraflow lane heading south. Only happens in my T6, not my golf and generally in wet weather.

I complained to the dealer but they fobbed me off saying the sensors may not work during rain. Unbelievable.
The one time the ACC is useful it doesn’t work and I fail to see VW didn’t anticipate owners would want to use it in the rain.

Matt

 

[Cosyvan-tooti]

I’ve had my T6 from new for just coming up to 3 years and this same issue has only ever happened once to me....and on exactly the same stretch of motorway in the contra flow. It’s in for another small bit of warranty work next week and whilst it’s there I’ve asked them to check the diagnostic log to see what the issue was. It went off, error message and then couldn’t re-engage the ACC for about an hour. Worked perfectly since.

 

[kurienp]

I’ve had my T6 from new for just coming up to 3 years and this same issue has only ever happened once to me....and on exactly the same stretch of motorway in the contra flow. It’s in for another small bit of warranty work next week and whilst it’s there I’ve asked them to check the diagnostic log to see what the issue was. It went off, error message and then couldn’t re-engage the ACC for about an hour. Worked perfectly since.

Interesting Ben. Everything points to some kind of interference and nothing to do with the Cali or ACC config. Will be interesting to see what the service tech says. Most probably it will be "all is well" and worst case "they all do that once in a while sire"

And a warm welcome on board.

 

[chockswahay]

OK, I just found this thread as I was looking for ACC issue. Recently whilst driving along a dual carriageway with a similar lane closure as described in post #1 my Acc came up with same warning….. this might not really have been an issue other than the van then accelerating towards the slowing traffic! Yes I know we should always be on our guard and monitoring the systems/ speeds/ traffic etc but for a few moments this was a heart pulse increasing moment!

So it would appear these are not unknown events but it was the first time I have had an ACC failure then for the vehicle to accelerate! I would have thought that the logic should be that if the ACC fails then the previously selected speed should be ignored?

 

[kurienp]

OK, I just found this thread as I was looking for ACC issue. Recently whilst driving along a dual carriageway with a similar lane closure as described in post #1 my Acc came up with same warning….. this might not really have been an issue other than the van then accelerating towards the slowing traffic! Yes I know we should always be on our guard and monitoring the systems/ speeds/ traffic etc but for a few moments this was a heart pulse increasing moment!

So it would appear these are not unknown events but it was the first time I have had an ACC failure then for the vehicle to accelerate! I would have thought that the logic should be that if the ACC fails then the previously selected speed should be ignored?

Ha ha! Those times when you then bang on the brakes and tell the wife - that was the ACC not me!

Yes, it is a scary moment when it accelerates - you would think it will/should slow down! If a driver does not have quick reaction times, it can definitely lead to an accident.

Flowing bends in roads - another place to watch out where the ACC totally loses it at times

Drive safe!

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