PickUp Coil Variable Reluctance Type Sensors

The distance between the rotor and pickup coil is critical. The further apart they are, the weaker the signal.

Not all rotors use teeth. Sometimes the rotor is notched, which will produce the same effect.

These sensors generate AC voltage, and do not need an external power supply. Another common characteristic is that they have two wires to carry the AC voltage.

The wires are twisted and shielded to prevent electrical interference from disrupting the signal. The EWD will indicate if the wires are shielded.

By knowing the position of the camshaft, the ECM can determine when cylinder No. I is on the compression stroke. The ECM uses this information for fuel injection timing, for direct ignition systems and for variable valve timing systems.

This sensor is located near one of the camshafts. With variable timing V-type engines, there is one sensor for each cylinder bank. On distributor ignition systems, it is often called the G sensor and is located in the distributor.

An AC signal is generated that is directly proportional to camshaft speed. That is, as the camshaft revolves faster the frequency increases.

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