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How
to connect the oscilloscope - AC excited camshaft sensor
Plug
a BNC test lead into channel A on the ADC-212, place a
large black crocodile clip on the test lead with the black molding (negative) and an acupuncture probe onto the test lead with the red
molding (positive). Plug a BNC test lead into channel B on the ADC-212,
place an acupuncture probe onto the test lead with the red molding (positive).
Place the large black crocodile clip on to the battery negative and probe
the sensor with the two acupuncture probes.
The
sensor will have three wires, two of these will displayed the alternating
current (ac) waveform as illustrated in the example on this page, the other wire
will be an earth.
Fig. 13.1
Figure
13.1 shows the two acupuncture probes back probing the camshaft
sensor multiplug at the connection within the recess of the cam cover on the
Vauxhall ECO TEC engine.
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Example
AC excited camshaft sensor waveform
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 100 to 150
kHz (150,000 cycles per second) 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 to 20us/division 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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Technical
information - camshaft sensor
This
camshaft sensor differs in operation from the other sensors by having an
Alternating Current (AC) voltage supply to the CID sensor. The ECM supplies a
very high frequency at around 100 to 150 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.
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