Express 1/2 Ton Van V8-305 5.0L VIN M SFI (1998)
Crankshaft Position Sensor: Description and Operation
DESCRIPTION
The Crankshaft Position (CKP) Sensor is located in the front engine cover and is perpendicular to the crankshaft target wheel. The air gap
between the sensor and the wheel is preset and not adjustable. The target wheel has three slots 60° apart and is keyed to the crankshaft. As the
target wheel rotates, the slots passing by the sensor create a change in the magnetic field of the sensor which results in an induced voltage pulse.
One revolution of the crankshaft results in three pulses (3x signal). Based on these pulses, the VCM is able to determine crankshaft position and
engine speed. The VCM then activates the fuel injector and provides a spark to the Distributor. The relation between the crankshaft position sensor
and the target wheel is crucial. The sensor must be exactly perpendicular to the target wheel with the correct air gap.
OPERATION
The crankshaft position sensor provides the VCM with crankshaft speed and crankshaft position. The VCM utilizes this information to determine
if an engine Misfire is present. The VCM monitors the Crankshaft Position Sensor (CKP) sensor for momentarily drop in crankshaft speed to
determine if a misfire is occurring. When the VCM detects a misfire, a Diagnostic Trouble Code (DTC) P0300 will set. The VCM also monitors
the CKP sensor signal circuit for malfunctions. The VCM monitors CKP signal and the High and Low resolution signals. The VCM calculates
these signals to determine a ratio. When the VCM detects that the ratio is out of normal operating range, the VCM will set a Diagnostic Trouble
Code (DTC) P0337 or a DTC P0338.
