Crankshaft Position Sensor (Cps)
The CPS is attached to flywheel/drive plate housing. The sensor detects the flywheel/drive plate teeth as they pass during engine operation and provides engine speed and crankshaft angle (position) information to the ECU. See Fig 1 . The flywheel/drive plate has a large trigger tooth and notch located 90 degrees before each Top Dead Center (TDC) position. There are 12 small teeth between the notch and TDC. When a small tooth and notch pass under the magnetic core in the sensor, the concentration and collapse of the magnetic flux induces a small voltage spike into the sensor pick-up coil winding. These small voltage spikes enable the ECU to count the teeth as they pass the sensor.
When a large trigger tooth and notch pass under the magnetic core in the sensor, the increased concentration and collapse of the magnetic flux causes a higher voltage spike into the sensor pick-up coil winding. The higher voltage spike indicates to the ECU that a piston will be at TDC position 12 teeth later. The ignition timing for that cylinder will either be advanced or retarded as necessary by the ECU according to the sensor inputs.