Sensor, Crankshaft Position: Operation

The flywheel ring gear has many slots and one flat. Once the Powertrain Control Module (PCM) senses the last slot, it determines crankshaft position (which piston will be next at TDC) from the camshaft position sensor input. It may take the PCM up to one engine revolution to determine crankshaft position during cranking.

The PCM uses the camshaft position sensor to determine injector sequence. Once crankshaft position has been determined, the PCM begins energizing the injectors in sequence. The PCM determines ignition timing from the crankshaft timing sensor.