Crankshaft (3X/18X) Sensor (3.8L)

The 3.8L uses a 4-wire, dual (3X and 18X) Hall Effect switch Crankshaft Position (CKP) sensor. Sensor is located in an aluminum mounting bracket bolted to the front left side of the engine timing chain cover. Sensor contains 2 Hall Effect switches. Each Hall Effect switch alternately grounds and opens individual 12-volt signal circuits to ignition module.

An air gap separates each Hall Effect switch from a magnet. Two interrupter rings are mounted on the vibration damper and rotate with the crankshaft. The inner interrupter ring contains 3 unevenly-spaced, unequal-width blades. The outer interrupter ring contains 18 evenly-spaced, equal-width blades.

When the Hall Effect switch is shielded from the magnetic field generated by the magnet by one of the interrupter blades, the 12-volt signal circuit is not grounded by the Hall Effect switch. When each Hall Effect switch is exposed to the magnetic field, the 12-volt signal circuit is grounded by the Hall Effect switch. The constant grounding and opening of these 12-volt signal circuits result in a toggling on/off signal which the ignition module interprets as RPM (engine speed).

The comparison on these 2 differing signals generated by the 3X and 18X Hall Effect switches enables ignition control module to verify synch pulse accuracy. The 3X and 18X signals are passed on to the PCM which uses these signals to determine crankshaft position, RPM and necessary spark timing adjustments. For additional information, see COMPUTER CONTROLLED COIL IGNITION (C3I)  under IGNITION SYSTEM.