Crankshaft Position Sensor

Fig 1: Timing Slots On Crankshaft

Courtesy of DAIMLERCHRYSLER CORPORATION

The crankshaft position sensor detects slots cut into a disk in middle of crankshaft. See Fig 1 . There are 5 sets of slots. Each set contains 2 slots, for a total of 10 slots. Basic timing is determined by position of last slot in each group. Once Powertrain Control Module (PCM) senses last slot, it determines crankshaft position (which piston will be next at TDC) from camshaft position sensor input. It may take PCM up to one engine revolution to determine crankshaft position during cranking.

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