Lumina V6-191 3.1L VIN T MFI (1993)
Dual Crankshaft Sensor: Description and Operation
Crankshaft Position (CKP) Sensor(s)
3X Sensor
Typical DIS Crankshaft Sensor
PURPOSE:
The crankshaft sensor provides a signal through the Direct Ignition (DI), which the ECM uses as reference to calculate rpm and crankshaft
position.
OPERATION:
This sensor protrudes into the block, within approximately .050" of the engine crankshaft reluctor. The reluctor is a special wheel cast into the
crankshaft with seven slots cast 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." As the reluctor rotates as part of the crankshaft, the slots change the magnetic field of the sensor, creating an induced
voltage pulse.
Based on the crank sensor pulses, the ignition module sends reference signals to the ECM which are used to indicate crankshaft position and
engine speed.
LOCATION:
This sensor is mounted remotely from the ignition module, right hand side of engine, at the end of the crank shaft.
24X Sensor
24X Crankshaft Sensor Installation
PURPOSE
The 24X crankshaft sensor is used to improve idle spark control at engine speeds up to approximately 2000 rpm.
OPERATION
The 24X crank sensor contains a Hall-effect switch. The magnet and hall-effect switch are separated by an air gap. The 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 switch and the magnet, the signal voltage is not grounded. If the piece of steel is
repeatedly moved in and out of the air gap, the signal voltage will appear to cycle. The piece of steel is the interrupter ring 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 let it pass to one of the Hall-effect
switches. The Hall-Effect switch is called the 24X crank sensor because this interrupt ring has 24 evenly spaced blades and windows which are all
the same width. The 24X crank sensor produces 24 "ON-OFF" pulses per crankshaft revolution. The hall-effect switch closest to the crankshaft,
the 3X crankshaft sensor, is so called because the interrupter ring has a special wheel cast on the crankshaft that has seven machined slots, six of
