Grand Prix V6-204 3.4L DOHC (1992)
Crankshaft Position Sensor: Description and Operation
PURPOSE
The crankshaft sensor provides crankshaft position and engine speed information to the ignition module and control unit. The computer uses this
information, compared with information from other sensors, to regulate fuel injection, ignition timing, and emission control systems.
Typical DIS Crankshaft Sensor
LOCATION AND OPERATION
This crankshaft sensor is an inductive sensor mounted remotely on the opposite side of the engine from the DIS module. This sensor protrudes into the
block, within approximately .050" of the engine crankshaft reluctor. The reluctor is a special wheel cast into the crankshaft with seven slots machined
into it, six of which are evenly spaced 60° apart. A seventh slot is spaced 10° from one of the other slots and serves to generate a "sync pulse,"
indicating the exact position of the crankshaft once each revolution. As the crankshaft rotates, the slots in the reluctor wheel cause changes in the
magnetic field of the sensor, inducing a voltage pulse that is easily measured.
By measuring the time between pulses, the DIS module can recognize the pulse representing the seventh slot or "sync pulse." Based on this "sync
pulse," the DIS module sends a reference signal to the ECM to calculate crankshaft position (used to fire the ignition coils in correct sequence) and
engine speed.
