Inductive sensors produce an AC Sine Wave signal. The AC voltage is induced by the shifting of a magnetic field. The sensor consists of an impulse wheel (the moving part) and a coil wound magnetic core (the stationary part).

As each tooth of the impulse wheel approaches the sensor tip, the magnetic field of the sensor shifts toward the impulse wheel and induces a voltage pulse in the windings.

As the teeth move away from the sensor, the magnetic field shifts back inducing a voltage pulse in the opposite direction.

This shifting of the magnetic field produces an alternating current (positive to negative).

Control modules which receive this alternating current, count the impulses (shifts from positive to negative) and interpret the speed of rotation of the impulse wheel.

Fig 1: Inductive Sensor Circuit Diagram

Courtesy of BMW OF NORTH AMERICA, INC.

Typical Application of Inductive Sensors:

Crankshaft Speed Sensor.
Camshaft Speed Sensor.
Transmission Input/Output Speed Sensor.
Wheel Speed Sensor.

Fig 2: Identifying AC Sine Wave Signal

Courtesy of BMW OF NORTH AMERICA, INC.

Voltage levels are dependent on sensor design.

Not all inductive sensors produce 12 volts.

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

Inductive Sensors

Use the Manual With the Right Hardware

When to See a Mechanic

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