Crankshaft Position Sensor: Description and Operation

Fig 6 Crankshaft Position Sensor:

Fig 7 Timing Slots:

Fig 8 Crankshaft Position Sensor:

OPERATION
The crankshaft position sensor detects slots cut into the transmission driveplate extension (Fig. 7). There are 3 sets of slots. Each set contains 4 slots, for a total of 12 slots.

Basic timing is set by the position of the last slot in each group. Once the Powertrain Control Module (PCM) senses the last slot, it determines crankshaft position (which piston will next be at TDC) from the camshaft position sensor input. The 4 pulses generated by the crankshaft position sensor represent the 69°, 49°, 29°, and 9° BTDC marks. It may take the PCM one engine revolution to determine crankshaft position.

The PCM uses crankshaft position reference to determine injector sequence, ignition timing and the presence of misfire. Once the PCM determines crankshaft position, it begins energizing the injectors in sequence.

The crankshaft sensor is located on the passengers side of the transmission housing, above the differential housing (Fig. 8). The bottom of the sensor is positioned next to the drive plate.

CIRCUIT OPERATION
Circuit K7 supplies 8 volts from the Powertrain Control Module (PCM) to the crankshaft position sensor. The K7 circuit originates at cavity 44 of the PCM connector.

Circuit K24 from the sensor provides an input signal to the PCM. The K24 circuit connects to cavity 32 of the PCM. On vehicles equipped with an electronically controlled automatic trans axle, circuit K24 splices to the transmission control module.

The PCM provides ground for the crankshaft position sensor signal (circuit K24) through circuit K4. Circuit K4 connects to cavity 43 of the PCM.

Helpful Information
Circuit K7 also splices to supply 8 volts to the camshaft position sensor and vehicle speed sensor.

Circuit K4 also splices to supply ground for the signals from the following:
- Upstream heated oxygen sensor
- Downstream heated oxygen sensor
- Camshaft position sensor
- Throttle position sensor
- Manifold absolute pressure sensor
- Engine coolant temperature sensor
- Knock sensor
- Intake air temperature sensor
- Vehicle speed sensor