How Do Crankshaft Sensors Work?

In this post, we’ll take a look at how do crankshaft sensors work.

Crankshaft Sensors measure the speed and position of the camshaft and crankshaft. Their signal is processed by the ECU to optimize the accuracy of ignition and fuel control.

The crankshaft position sensor or camshaft position sensor is used to provide feedback to the engine control unit (ECU) that the timing of the engine is correct. It is also used to monitor the operation of the timing chain drive system.

In general, a crankshaft position sensor is a four-pin device that fits into a corresponding slot in the crankshaft. The sensor itself consists of a plastic housing that contains magnets and a Hall effect chip. Camshaft position sensors are usually located on the cylinder head cover of the engine. They are typically attached to the camshaft using a spring. Crankshaft position sensors are generally used in applications that require high reliability and accuracy. 

There are two types of sensors: Hall effect sensors and inductive sensors. Their function is fundamentally similar, although the construction can vary depending on the type of sensor and its intended use by the vehicle manufacturer.

Hall Effect Sensors

Hall effect sensors have an integrated circuit located between the rotor and a permanent magnet that generates a magnetic field vertical to the hall element. It is used in the integrated circuit to process signals that come in as electronic waves.

A Hall effect sensor has a magnetic field that changes when an object enters the sensor’s area of influence.

This detects the presence of a vehicle within the detection zone, and uses this information to turn on an LED that illuminates the detection zone for an approximate duration of time determined by a timer.

The uses of these sensors have evolved over time as the demands for better performance and lower emissions have increased. They are able to measure the exact injection time and duration, and adjust the ignition camshaft.

Inductive Sensors

A piezoelectric transducer consists of a piezoelectric material sandwiched between two electrodes.

When the ferromagnetic trigger wheel is rotated close enough to the soft iron core of the sensor, it changes the magnetic field surrounding the coil.

When a current is applied to the coil, a voltage is generated that is proportional to the strength and rate of change of the magnetic field.

Every time a tooth passes the sensor, a complete vibration is generated.

AC voltage is generated when a current passes through a coil.

Starting the engine in your car means that a voltage of up to two volts should be expected, but with increasing engine speed, the voltage will be higher.

The generated output voltage signal is not high in energy, which means it’s easy to be affected by strong external signals, for example the ignition system.

What will a bad crankshaft position sensor do?

A broken position sensor cannot give correct information to the ignition system, causing misfiring in the combustion chambers.

It’s possible that the timing will check out, but if the crankshaft sensor is damaged or isn’t working, then the engine could be faulty.

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