Lose speedo and then its back.

Hi all, I recall seeing mention a while back of someone losing their speedo whilst driving along but i don't recall if it ever came back or just died.

I am aware of the issues with the capacitors/resistors in the clocks themselves but i dont think thats the issue here as the clock self test (turn ignition on whilst holding check control button in) works fine and all the dials act as they should during that test.

I am unsure of whether it could be the speed sending unit and if so where abouts is that located (one of the wheels, gearbox housing etc?).

The problem started happening a couple of days ago. I can be driving along and then all of a sudden the needle just drops to 0 and then if i pick up speed to about 80mph it comes back again (similar to the position on the dial test) and if i dont drive slowly down from 80 to a normal speed it dies again. If i drop the speed too quick ie up to 80 down to 50 it will take a few minutes before the speedo then kicks back into gear and doesn't do this again until i have stopped using the car for a while and then it starts up again.

Rather than me take the clocks out and test this i would like to check out the speedo sending unit as I have a hunch that it is this thats causing the problem.

Any and all help gladly appreciated.

Russ

Edit: None of the other dials are affected just the speedometer.

Thanks Miles I phoned and ordered a new one from BMW yesterday should be there tomorrow. I presume its accessable from outside the diff rather than having to take the diff off to get at it?

Russ