Camshaft Sensor (Inductive) Waveform Notes
The camshaft sensor is sometimes referred to as the Cylinder
Identification (CID) sensor or a 'phase' sensor and is used as a reference
to time the sequential fuel injection by the Electronic Control Module
(ECM).
This particular type of sensor generates its own signal and therefore
does not require a voltage supply to power it. It is recognisable by its
two electrical connections, with the occasional addition of a coaxial
shielding wire.
The voltage produced by the camshaft sensor will be determined by several
factors, these being the engine's speed, the proximity of the metal rotor
to the pick-up and the strength of the magnetic field offered by the sensor.
The ECM needs to see the signal when the engine is started for its reference;
if absent it can alter the point at which the fuel is injected. The driver
of the vehicle may not be aware that the vehicle has a problem if the
CID sensor fails, as the drivability may not be affected.
The characteristics of a good inductive camshaft sensor
waveform is a sinewave that increases in magnitude as the engine speed
is increased and usually provides one signal per 720° of crankshaft rotation
(360° of camshaft rotation). The voltage will be approximately 0.5 volts
peak to peak while the engine is cranking, rising to around 2.5 volts
peak to peak at idle as seen in the example show.
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