Camshaft Sensor (AC Excited) Waveform Notes
This type of sensor is used on some of the Vauxhall ECO TEC engines.
This Cylinder Identification (CID) sensor differs in operation from the
other inductive sensors by having an Alternating Current (AC) voltage
supply to the CID sensor. The Electronic Control Module (ECM) supplies
a very high frequency at around 120 kHz to an exciter coil that is located
in close proximity to a rotating disc.
The disc is located at the end of the camshaft and has a section removed
that when 'open' allows the frequency to excite the receptor (through
mutual inductance) and returns the signal to the ECM, indicating the position
of number 1 cylinder.
As the frequency is so fast, the time scale should be set as fast as
possible so as the oscilloscope can capture the frequency.
The CID sensor is used as a reference for the ECM to determine the camshaft's
position, from which the correct timing for the sequential fuel injection
can be determined.
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