Riviera V6-3.8L SC VIN 1 (1995)
Crankshaft Position Sensor: Description and Operation
Crankshaft Sensor
Crankshaft Balancer With Interrupter Rings
Crank Sensor Pulses
DESCRIPTION
The dual crankshaft position sensor, secured in an aluminum mounting bracket and bolted to the front left side of the engine timing chain cover, is
partially behind the crankshaft balancer. A 4-wire harness connector plugs into the sensor, connecting it to the electronic ignition module.
The dual crankshaft position sensor contains two Hall-effect switches with one shared magnet mounted between them. The magnet and each
Hall-effect switch are separated by an air gap. A Hall-effect switch reacts like a solid-state switch, grounding a low-current signal voltage when a
magnetic field is present. When the magnetic field is shielded from the switch by a piece of steel placed in the air gap between the magnet and the
switch, the signal voltage is not grounded. If the piece of steel (called an interrupter) is repeatedly moved in and out of the air gap, the signal
voltage will appear to go "ON-OFF-ON-OFF-ON-OFF." Compared to a conventional mechanical distributor, this "ON-OFF" signal is similar to
the signal that a set of breaker points in the distributor would generate as the distributor shaft turned and the points opened and closed.
OPERATION
In the case of the electronic ignition system, the piece of steel is two concentric interrupter rings mounted to the rear of the crankshaft balancer.
Each interrupter ring has blades and windows that, with crankshaft rotation, either block the magnetic field or allow it to reach one of the
Hall-effect switches. The outer Hall-effect switch is called the 18X crankshaft position sensor, because the outer interrupter ring has 18
evenly-spaced same-width blades and windows. The 18X crankshaft position sensor produces 18 "ON-OFF" pulses per crankshaft revolution. The
Hall-effect switch closest to the crankshaft, the 3X crankshaft position sensor, is so called because the inside interrupter ring has 3
