Camshaft Position Sensor - DaimlerChrysler LH New Yorker 1994 Electronic Service Manual

Fig. 10 Spark Plug Overheating
Fig. 11 Camshaft Position Sensor—3.3L Engine
Fig. 12 Camshaft Position Sensor—3.5L Engine

CAMSHAFT POSITION SENSOR

The camshaft position sensor provides cylinder
identification to the powertrain control module (PCM)
(Fig. 11 or Fig. 12). The sensor generates pulses as
groups of notches on the camshaft sprocket pass un-
derneath it (Fig. 13 or Fig. 14). The PCM keeps track
of crankshaft rotation and identifies each cylinder by
the pulses generated by the notches on the camshaft
sprocket. Four crankshaft pulses follow each group of
camshaft pulses.
When the PCM receives two cam pulses followed by
the long flat spot on the camshaft sprocket, it knows
that the crankshaft timing marks for cylinder one are
next (on driveplate). When the PCM receives one
camshaft pulse after the long flat spot on the
sprocket, cylinder number two crankshaft timing
IGNITION SYSTEMS
Fig. 13 Camshaft Sprocket—3.3L Engine
Fig. 14 Camshaft Sprocket—3.5L Engine
marks are next. After 3 camshaft pulses, the PCM
knows cylinder four crankshaft timing marks follow.
One camshaft pulse after the three pulses indicates
cylinder five. The two camshaft pulses after cylinder
5 signals cylinder six (Fig. 13 or Fig. 14). The PCM
can synchronize on cylinders 1 or 4.
When metal aligns with the sensor, voltage goes low
(less than 0.3 volts). When a notch aligns with the
sensor, voltage spikes high (5.0 volts). As a group of
notches pass under the sensor, the voltage switches
from low (metal) to high (notch) then back to low. The
number of notches determine the amount of pulses. If
available, an oscilloscope can display the square wave
patterns of each timing event.
Top dead center (TDC) does not occur when notches
on the camshaft sprocket pass below the cylinder.
8D - 5