Crankshaft Position Sensor

The 4.6L Direct Ignition System (DIS) crankshaft position sensor protrudes through side of engine block to within .05" (1.3 mm) of an internally-mounted crankshaft reluctor ring. The reluctor ring is a special trigger wheel cast into the crankshaft. As crankshaft rotates, notches in reluctor ring change the magnetic field at the tip of the position sensor. This creates an induced AC voltage signal in the sensor windings, resulting in reference signals which are sent to PCM by ignition module. This allows PCM to compute crankshaft position and RPM and fire appropriate ignition coil at the proper time.

Vehicles equipped with HEI-EST distributor systems use RPM reference signal from ignition module in distributor for a crankshaft position signal. TDC intake and TDC exhaust are not differentiated; differentiation is not necessary on non-sequential fuel injected engines. Signal is used to trigger fuel injectors. For additional information, see DIRECT IGNITION SYSTEM (DIS)  under IGNITION SYSTEM.