Hi,

After a bit of wisdom from the masses with experience please.......

Bottom line question is "What causes the ACC / Forward Alert to report that it's blocked ?" Is it x% of failed returned pulses, or something else ??

Some days I can drive for hundreds of miles with no problems, other days it shuts down within minutes, but will allow to be re-selected many minutes later, only to fail minutes later again.

I've had the car dirty, in heavy rain working fine for hours - and also failing quickly on clear days with a clean car. It's failed on the same stretch of road with the same traffic conditions and worked fine the next day on the same road road with same traffic conditions. Every time it fails an engine restart will turn it back on again immediately.

There doesn't seem to be any common reason.

I've not had the bumper off yet to inspect the radar unit, may do this.

Does anyone know of the re-callibration process needed ????

Thanks in advance

David

My experience with it on a 2007 RRS TDV8 was that it would shut down on slushy/ snowy days which was a pain as there was no way to have conventional cruise when the adaptive stopped on a long motorway haul. As it isn't the snow season yet the only thing I could think of that might cause it to give the blocked message might be getting a lot of squashed flies on the sensor. 2020 Pangea Green 1st Edition D240 New Defender 110 is here and loving it
2018 Melting Silver Mini Countryman PHEV - soon to be replaced
2015MY Corris Grey SDv6 HSE Dynamic, the best car I have ever owned, totally reliable only a cou0le of rattles in 3 years, now no longer in my care
Also in my garage is a 1996 TDi300 Defender 90 County HT made into a fake CSW

Thanks Tim - that's the thing, it'll fail when the car is clean AND work when it's clean - it'll fail when it's dirty AND work when it's dirty. It'll work when it's raining and fail when it's raining. It'll work following a tractor at 25mph and fail following a tractor the next day.

When it fails, I can wait sometimes seconds to turn it back on (through the menu) other times it can be 10-20 minutes before it's allowed to be turned back on.

Can't seem to work out anything common - so starting to think it's calibration - someone once said there's a calibration routine for it that takes a while but can't seem to find detail.

mine did exactly the same, until the gearbox blew
rebuilt gearbox over 18 months ago, and not had the issue since, the autobox man said one of the speed sensors is taken from the gearbox and if that gives a false reading it shuts the system down 07,TDV8,Black, Black Heated leather all round, Rear Entertainment with Headpones & Remote, TV, DVD, Pure Dab Digital Radio, Sidesteps, Adaptive Headlights, sunroof, now working fuel burning heater )))