Info 1) http://de.wikipedia.org/wiki/Hallsonde
Info 2)
CAS (KWS)
The CAS consists of a toothed disk and an two coils (exciter and modulator). The disk is attached to the crankshaft and
theoretically comprises 59 teeth set around its circumference. At a position 114° BTDC, one tooth is omitted as a reference to
TDC and so a total of 58 teeth remain on the disk. A high frequency signal of between 120 and 180 khz is delivered to the exciter
coil by the ECM.
As the crankshaft spins, and the teeth are rotated in the exciter coil field, a modulation occurs which is returned to the ECM to
indicate speed of crankshaft rotation and a reference to TDC as an indication of crankshaft position. The ECM makes a digital
comparison of both ECM and CAS output signals and registers a phase difference that is proportional to the CAS output.
If the CAS were to fail, the ECM logs a fault code and enters LOS mode utilising the signal from the CID sensor. If both sensors
were to fail, ignition operation would be inhibited for safety purposes.
CID (NWS)
The camshaft sensor operates on the same principle as the CAS. The CID sensor consists of a disk with one segment and an
exciter coil. The disk is attached to the camshaft. A high frequency signal of between 120 and 180 khz is delivered to the exciter
coil by the ECM. As the camshaft spins, and the segment is rotated in the exciter coil field, a modulation occurs which is returned
to the ECM to indicate the position of number one cylinder. The ECM makes a digital comparison of both ECM and CID sensor
output signals and registers a phase difference that is proportional to the CID position.
If the CID sensor were to fail, the ECM logs a fault code and enters LOS mode utilising the signal from the CAS. If both sensors
were to fail, ignition operation would be inhibited for safety purposes.