How a Crankshaft Sensor Works

A crankshaft sensor is a component in a vehicle’s engine that monitors the position or the speed of rotation of the crankshaft. The information that the crankshaft sensor gathers is often used to control the ignition timing system. It watches the position of the camshaft and its relationship with the piston position inside the vehicle’s engine. This small component in the vehicle’s engine is a sort of a trigger device that is used for Distributorless Ignition Systems (DIS), which informs the ignition module when to fire the spark plugs.

This sensor is so important that if it is not working properly the engine will be likely to perform less than its efficiency level. At the same time, the warning light of the Electronic Control Unit or ECU will be turned on.

Location of the Crankshaft Sensor

This important component of the engine is generally located on the fuel injection engines. Generally, the crankshaft sensor is located beside the crankshaft or beside the cam belt. However, depending on the make and model of the vehicle it can also be found in the main crank pulley or the flywheel.

Parts of the Crankshaft Sensor

Although a small component, there are several parts of the crankshaft sensor. The crankshaft sensor, also known as crankshaft position sensor, is generally used on modern cars. The crankshaft sensor is typically made of the rotating part which is like a disc and the actual sensor which is a static part.

The Process of a Crankshaft Sensor

Around the circumference of the crankshaft or the flywheel, you will find several steel pegs or steps. These pegs have different thicknesses of material. The angle where the pegs are situated depends largely on what the engine is but generally it is set at 10 degrees.

Mounted close to the flywheel is a permanent magnet which acts as an inductive signal generator. This permanent magnet gives out a magnetic field that the crankshaft sensor senses. Every time the flywheel spins, the steps or pins around the crankshaft rotates.

During this rotation, an Alternating Current (AC) or alternating waveform output signal is produced. The current is then sent to the Engine Management Unit. EMU uses the information it gathered to then calculate the speed of the rotation.

Checking the Crankshaft Sensor

Crankshaft sensors are often found in DIS (Distributorless Ignition System) vehicles. This means that the vehicle is running without the need for a rotor or distributor cap. This also means that the vehicle can run without too many problems caused by a faulty vacuum or any mechanical advance mechanism that can cause timing problems.

To check if the crankshaft sensor is working properly, unplug the electrical connector. You then need to check the resistance between the appropriate terminals. You need to replace your crankshaft sensor if you find that the resistance is not within specifications.