All you guys are thinking the same way i did.

Checked all the charge rates. 13v@idle 13.8@revs

Cleaned every contact pug and socket even the ovp

In the centre of the ABS wheel sensor there`s a magnetic insert that i take is the actual pick up, it has i knife edge on the end (looks like the end of a screwdriver). I`m wondering if maybe a rock can get thown up and upset it`s orientation, it seems that if you grab it that you may be able to turn it to change the angle of the knife edge to the wheel hub.
Can anyone comment on this before i break it by trying to turn it.