Operation

The rpm sensor is fitted to the engine crank-case and faces the phonic wheel on the crankshaft.

The sensor is inductive type, i.e. it works by varying a magnetic field generated when the phonic wheel teeth (60-2 teeth) pass in front of the sensor element.

The injection control unit uses the rpm sensor signal to determine crankshaft speed and angular position.

Operation

The changeover from full to empty due to the presence or absence of teeth sets up a magnetic flux change sufficient to generate an induced alternating voltage proportional to the number of teeth on the phonic wheel.

The peak sensor output voltage value, all things being equal, depends on the distance between the sensor and the tooth (gap).

1. Steel bush
2. Permanent magnet
3. Sensor case
4. Winding
5. Core
6. Phonic wheel
7. Electrical connection

To obtain the correct signal, the specified gap between phonic wheel and sensor should be between 0.8 and 1.5 mm

This distance is not adjustable. When the gap is not as specified, check the condition of the sensor and phonic wheel.

Winding resistance 860 Ohm ±10% at 20 °C

1. Maximum magnetic flux
2. Minimum magnetic flux
3. Induced alternate voltage