Crankshaft Position Sensor: Description and Operation

Crankshaft Position Sensors:

Ignition System Synchronization:

DESCRIPTION
The two crankshaft sensors are located on the front bank (BANK 2) of the engine block between cylinders 4 and 6. Crankshaft position "A" sensor is located in the upper crankcase and crankshaft position "B" sensor is located in the lower crankcase. Both sensors extend into the crankcase and are sealed to the engine block with O-rings. The crankshaft position sensors are not adjustable.


OPERATION
The magnetic crankshaft position sensors operate similar to the pick-up coil in a distributor. When a piece of steel (called a reluctor) is repeatedly moved over the sensor, a voltage will be created by the sensor that appears to go "0N-0FF-0N-0FF-0N-0FF." This "ON-OFF" signal is also similar to the signal that a set of breaker points in a distributor would generate as the distributor shaft turned and the points opened and closed.

The reluctor ring is cast onto the crankshaft between the #3 and #4 main bearing journals. The interrupter ring has 24 evenly spaced notches or air gaps and an additional 8 unevenly spaced notches for a total of 32.

As the crankshaft makes one complete revolution, both the "A" and "B" sensors will produce 32 "ON-OFF" pulses per revolution. In addition, the "A" sensor is positioned 27 degrees of crankshaft revolution before the "B" sensor. This creates a unique pattern of "ON-OFF" pulses sent to the ignition control module so that it can recognize crankshaft position.

CRANKSHAFT REFERENCE GROUND
This is a ground circuit for the digital RPM counter inside the PCM, but the wire is connected to engine ground ONLY through the ignition module. Although this circuit is electrically connected to the PCM, it is NOT connected to ground AT the PCM. The PCM compares voltage pulses on the reference input CKT 430 to any on this circuit, ignoring pulses that ground on both. If the circuit is open, or connected to ground at the PCM, it may cause poor engine performance and possibly a "Service Engine Soon/MIL" light with no DTC.