Engines; Crankshaft Position Sensor-3.9L V-6 Or 5.2/5.9L V-8 Engines - Dodge RAM TRUCK 1500 1995 Service Manual

IGNITION SYSTEMS 8D - 3
utor shaft. The pulse ring rotates 180 degrees
through the sync signal generator. Its signal is used
in conjunction with the crankshaft position sensor to
differentiate between fuel injection and spark events.
It is also used to synchronize the fuel injectors with
their respective cylinders.
When the leading edge of the pulse ring (shutter)
enters the sync signal generator, the following occurs:
The interruption of magnetic field causes the voltage
to switch high resulting in a sync signal of approxi­
mately 5 volts.
When the trailing edge of the pulse ring (shutter)
leaves the sync signal generator, the following occurs:
The change of the magnetic field causes the sync sig­
nal voltage to switch low to 0 volts.
For component testing, refer to the Diagnostics/Ser­
vice Procedures section of this group.
For removal and installation of this component, re­
fer to the Component Removal/Installation section of
this group.
CAMSHAFT POSITION SENSOR—8.0L V-10
ENGINE
The camshaft position sensor is located in the tim­
ing chain case/cover on the left-front side of the en­
gine (Fig. 4). A machined hole is provided in the
timing chain cover to place the face of the sensor
next to the upper camshaft drive gear. A slot and a
single bolt are provided on the sensor for depth ad­
justment (Fig. 4).
Fig. 4 Camshaft Position Sensor—8.0L V-10
Engine—Typical
SENSOR OPERATION—8.0L V-10 ENGINE
The camshaft position sensor is used in conjunction
with the crankshaft position sensor to differentiate
between fuel injection and spark events. It is also
used to synchronize the fuel injectors with their re­
spective cylinders. The sensor generates electrical
pulses. These pulses (signals) are sent to the power-
train control module (PCM). The PCM will then de­
termine crankshaft position from both the camshaft
position sensor and crankshaft position sensor.
The camshaft position sensor detects notches in the
upper camshaft drive gear (Fig. 5). The face of the
sensor is positioned next to this gear with a small air
gap.
Fig. 5 Sensor Operation—8.0L V-10 Engine
When the gear is rotating, the sensor will detect
one of these notches. Input voltage from the sensor to
the PCM will then switch from a low (approximately
0.3 volts) to a high (approximately 5 volts). As the
notch moves away from the sensor, the input voltage
switches back low to 0.3 volts.
CRANKSHAFT POSITION SENSOR—3.9L V-6 OR
5 J / I J L V-8 ENGINES
The sensor is bolted to the top of cylinder block
near the rear of the right cylinder head (Fig. 6).
Engine speed and crankshaft position are provided
through the crankshaft position sensor. The sensor
generates pulses that are the input sent to the pow­
ertrain control module (PCM). The PCM interprets
the sensor input to determine the crankshaft posi­
tion. The PCM then uses this position, along with
other inputs, to determine injector sequence and ig­
nition timing.
The sensor is a hall effect device combined with an
internal magnet. It is also sensitive to steel within a
certain distance from it.
SENSOR OPERATION—3.9L V-6 ENGINE
The flywheel/drive plate has groups of notches at
its outer edge. On 3.9L V-6 engines, there are three
sets of double notches and three sets of single
notches (Fig. 7).
The notches cause a pulse to be generated when
they pass under the sensor. The pulses are the input
to the PCM.
The engine will not operate if the PCM does not re­
ceive a crankshaft position sensor input.