Crankshaft Sensors - California Emissions (GEN-II S)

Ignition Control Module Circuit Diagram:

Cam And Crankshaft Sensor Circuit Diagram:

GENERAL INFORMATION
This engine uses two crankshaft position sensors. One sensor, mounted on the side of the engine block (3X crankshaft sensor), and another (24X sensor) mounted on the front of the engine behind the harmonic balancer.


PURPOSE
The 3X crankshaft sensor provides crankshaft position and engine speed information to the ignition module and control unit. The signal indicates the exact position of the crankshaft once each revolution, and the relative position every 60° thereafter. This signal is used as a reference for fuel injection, ignition timing, and engine speed calculations.

The 24X crankshaft sensor produces a signal every 15° of crankshaft rotation for ignition timing calculations.

Crankshaft Position Sensor Installation:

LOCATION AND OPERATION (3X SENSOR)
This 3X crankshaft sensor is hall-effect sensor mounted on the side of the engine block. This sensor protrudes into the block, within approximately .050" of the engine crankshaft reluctor wheel. 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, turning the switch "OFF" and "ON" to produce a 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.

24X Crankshaft Sensor Installation:

LOCATION AND OPERATION (24X SENSOR)
This 24X crankshaft sensor is hall-effect sensor mounted on the front of the engine behind the harmonic balancer. The balancer has an "interrupter ring" with 24 slots (hence the name 24X crankshaft sensor). As the slots pass the sensor, the hall-effect switch is turned "ON" and "OFF" again, producing a signal that can be easily read. The signal indicates the relative crankshaft position every 15° of rotation and is used to determine correct ignition timing.