Info re battery sensor on the neg battery terminal:
http://www.hella.com/emergency/en/In...ensor-543.html
http://www.hella.com/emergency/asset...V_HELLA_EN.pdf
The Hella part number partly matches the FoMoCo labelled sensor on my MC TDCi in 6PK 010, and looks much the same.
The meaning of ASIC in this context -
'application specific integrated circuit' it seems.
So the single wire to the +ve terminal is the supply to the sensor and the the single white wire from the sensor is the LIN communication wire.