CRANKSHAFT POSITION SENSOR
DESCRIPTION
The crankshaft position sensor mounts to the rear of the engine block near the transmission.
The PCM uses the Crankshaft Position sensor to cal-
culate the following:
•
Engine RPM
•
TDC number 1 and 4
•
Ignition coil synchronization
•
Injector synchronization
•
Camshaft-to-crankshaft misalignment (Timing belt
skipped 1 tooth or more diagnostic trouble code).
OPERATION
The PCM sends approximately 5 volts to the Hall-effect sensor. This voltage is required to operate the Hall-effect
chip and the electronics inside the sensor. A ground for the sensor is provided through the sensor return circuit. The
input to the PCM occurs on a 5 volt output reference circuit that operates as follows: The Hall-effect sensor contains
a powerful magnet. As the magnetic field passes over the dense portion of the counterweight, the 5-volt signal is
pulled to ground (.3 volts) through a transistor in the sensor. When the magnetic field passes over the notches in
the crankshaft counterweight, the magnetic field turns off the transistor in the sensor, causing the PCM to register
the 5-volt signal. The PCM identifies crankshaft position by registering the change from 5 to 0 volts, as signaled
from the Crankshaft Position sensor (2).
The PCM determines what cylinder to fire from the crankshaft position sensor input and the camshaft position sen-
sor input. The #8 crankshaft counterweight has a target ring with 32 teeth and notches (1), including one long ref-
erence tooth and notch. From the crankshaft position sensor input the PCM determines engine speed and
crankshaft angle (position).
PM
FUEL INJECTION
14 - 57