Japanese Honda Crankshaft Sensors

Description

How the crankshaft position sensor works

The crankshaft position sensor is positioned so that teeth on the reluctor ring attached to the crankshaft pass close to the sensor tip. The reluctor ring has one or more teeth missing to provide the engine computer (PCM) with the reference point to the crankshaft position.

In this GM engine, the crankshaft position
sensor is installed at the cylinder block

As the crankshaft rotates, the sensor produces a pulsed voltage signal, where each pulse corresponds to the tooth on the reluctor ring. The photo below shows the actual signal from the crankshaft position sensor with the engine idling. In this vehicle, the reluctor ring is made with two missing teeth, as you can notice on the graph.

The PCM uses the signal from the crankshaft position sensor to determine at what time to produce the spark and in which cylinder. The signal from the crankshaft position is also used to monitor if any of the cylinders misfires.

Crankshaft position sensor signal on the oscilloscope screen.

If the signal from the sensor is missing, there will be no spark and fuel injectors won’t operate.

The two most common types are the magnetic sensors with a pick-up coil that produce A/C voltage and the Hall-effect sensors that produce a digital square wave signal as in the photo above. Modern cars use the Hall-effect sensors. A pick-up coil type sensor has a two-pin connector. The Hall-effect sensor has a three-pin connector (reference voltage, ground and signal).