Warning light,

[doberman19]

That's my thinking too, ie, a warning from the adaptive cruise control warning me to break but
when it happened last night I was just coming to the end of a long drive to meet the main road
so there seems to be no consistency in the way it happens. I've checked the handbook and the
 symbol that appears is not listed.

[fredgroves]

Its the anti collision system..."front assist"

And yes it can be a bit weird about what it thinks is a pending collision. It can get bad returns off of metal signs.

You can go into the menus and turn down the sensitivity - it might be set to max...

"front assist" works with or without cruise control active.

If when it pings up you don't take speed or direction changes after a split second it will lock the brakes on.... been there, done that.

[doberman19]

 Hi Fred, I think your right on the money in your last post. if you do not cancel the ACC it
is still active without you realising and on occasion it will warn you that you should be braking.
 I never realised that you had to manually turn it off, thanks for the wise words much
 appreciated, and thanks to all for your suggestions. doberman.