ACC slowing down while overtaking

[Digester-Man]

I have recently come back from France and noticed on my way up the M1 from Dublin that my van was slowing down as I was overtaking on the motorway. ACC showed a vehicle detected on the left side of the display rather than in the centre as you get when you approach a vehicle in your own lane. This was really infuriating and turning ACC on/off and turning on and off lane assist and crash detection didn't make any difference.

Any ideas? It never happened before I made a trip to the continent.

 

[Skyliner33]

I have recently come back from France and noticed on my way up the M1 from Dublin that my van was slowing down as I was overtaking on the motorway. ACC showed a vehicle detected on the left side of the display rather than in the centre as you get when you approach a vehicle in your own lane. This was really infuriating and turning ACC on/off and turning on and off lane assist and crash detection didn't make any difference.

Any ideas? It never happened before I made a trip to the continent.

Have you changed the headlight settings back for driving on the left, not the right?

 

[Digester-Man]

I didn't change any settings when I went to France. I had read on the forum that a T6.1 doesn't have any headlight settings that can be changed.

 

[Skyliner33]

I didn't change any settings when I went to France. I had read on the forum that a T6.1 doesn't have any headlight settings that can be changed.

Ah, you didn't specify you had a 6.1. It sounds like the van hasn't realised its back driving on the left.

 

[Robert]

... ACC showed a vehicle detected on the left side of the display rather than in the centre as you get when you approach a vehicle in your own lane...

Does it also detect vehicle on the right?
Technically it's undertaking but let's disregard legality element for the purpose of troubleshooting.

 

[Digester-Man]

Does it also detect vehicle on the right?
Technically it's undertaking but let's disregard legality element for the purpose of troubleshooting.

I haven’t tried that to be fair, was in the overtaking lane all the way home!!

 

[roadtripper]

What you describe is exactly the "no undertaking" behaviour we have on our 6.1 just reversed, so I agree most likely something in the van still thinks it's on continental roads.

 

[TeeCeeJay]

I have recently come back from France and noticed on my way up the M1 from Dublin that my van was slowing down as I was overtaking on the motorway. ACC showed a vehicle detected on the left side of the display rather than in the centre as you get when you approach a vehicle in your own lane. This was really infuriating and turning ACC on/off and turning on and off lane assist and crash detection didn't make any difference.

Any ideas? It never happened before I made a trip to the continent.

A short press on the accelerator will override it and let you continue the overtake. Had the same issue on my Golf, but that was combined with implausible speed sign recognition readings such as 85 or 120. Although it had never been on the continent, it would often behave as if it was driving on the right I ended up having to find the tech notes to give to the dealer to fix it.

 

[Skyliner33]

Does it also detect vehicle on the right?
Technically it's undertaking but let's disregard legality element for the purpose of troubleshooting.

T6.1 with ACC set won’t pass a vehicle in a lane to the right. It slows down to match that vehicle’s speed. If you the do a quick dab on the accelerator it will then “undertake”.

 

[Digester-Man]

I was forever dabbing the accelerator as the motorway was busy, it was a waste of time. In the end I unfortunately just turned it off.