Crankshaft Position Sensor: Description and Operation

Crankshaft Sensor:

Location

Mounted in transmission housing above distance sensor.

Purpose

PCM uses input to determine injector sequencing and ignition timing.

At start up, the PCM must determine crankshaft position, before energizing injectors in sequence.

Operation

Sensor detects a series of slots cut into the transmission driveplate extension.

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.

Note: It may take the PCM one engine revolution to determine crankshaft position.

Crankshaft Sensor:

Driveplate:

Sensor reads a series of slots cut in transmission driveplate.

Note: The distance between the sensor and torque converter drive plate is critical to system operation. Be sure paper spacer is attached to sensor face when installing sensor. SEE Powertrain Management/Computers and Control Systems/Camshaft Position Sensor/Service and Repair.