Just out of curiosity: are you sure about that, for dry tarmac and when not slamming it?
I mean I never saw in the UI the lock engaging (changing from green) in such circumstances.
Also many D4s do not even have a rear diff lock.
Printable View
My son monitored live values which revealed that the e-diff is pre-armed for possible wheel-spin and for lots of other circumstances too.
End of story (I presume, that is):
Genuine part part was sourced from Rimmer Bros at £437, and replaced at a local indy who has the needed calibration aparatus.
Original diff lock motor turned out to be seized.
First day out in the desert, the diff lock worked flawlessly.
Thank you guys for your helpful guidance.
Good that it's working again.
My MY21 L405 has a display that shows the extent of each of the rear and centre diffs locking, with a circle that is partly red indicating the percentage locked. Even very gentle straight-line acceleration on a sealed road shows the rear diff 100% locked up to about 70 kph and the centre diff starting at about 50% then gradually reducing to nil.
Here is one of my posts about the e-diff and the pre-emptive way that it operates
https://www.aulro.com/afvb/l322-rang...ml#post2602655
Download the pdf log here