Crankshaft Position Sensor : Components, Circuit, Working, vs Camshaft Position Sensor, Types, Testing & Its Applications

Automobile sensors have become very significant in modern automobiles to monitor various vehicle aspects and transmit data to the ECU or driver. The ECU in some conditions makes some adjustments to the specific component depending on the received data from the automobile sensors to maximize efficiency and performance. Generally, these sensors monitor different aspects like engine condition, temperature, oil pressure, coolant system, emission levels, vehicle speed, etc. There are different kinds of automobile sensors, like engine knock, airflow, engine speed, oxygen, voltage, throttle position, MAP, camshaft position sensor, airbag, car parking, crankshaft position sensor, etc. This article elaborates on the crankshaft position sensor, its working, and its uses.

What is a Crankshaft Position Sensor?

The crankshaft position sensor is a type of automobile sensor that monitors different engine parameters and also encompasses tasks like ignition timing establishment, engine RPM detection, deciding the precise engine’s crankshaft position, allowing relative engine speed, etc.

This automobile sensor removes the requirement of manual distributor timing by fulfilling all these functions. So this sensor helps in recognizing the firing cylinder, coil firing and synchronizing the fuel injector sequence in combination with the camshaft position sensor.

A crankshaft position sensor monitors the position and rotating crankshaft speed and position in an internal combustion engine by providing this information to the engine control unit for precise fuel injection & ignition timing control.

This sensor detects the crankshaft position by reading a ferromagnetic or magnetic encoder wheel located on the crankshaft. So this data includes the crankshaft’s RPM & position, which is sent to the engine control unit. So, this ECU utilizes this data to control ignition timing, fuel injection timing, engine parameters, etc.

Crankshaft Position Sensor Working Principle

The crankshaft position sensor works by detecting the position and rotational speed of the crankshaft and provides crucial information to the ECU (engine control unit) for exact fuel injection & ignition timing to ensure very smooth engine operation. This sensor monitors the movement of the crankshaft by allowing the ECU to decide the engine’s speed & the correct crankshaft position.

The crankshaft position sensor is normally arranged near a toothed wheel or reluctor ring connected to the crankshaft. When the crankshaft turns, the teeth of the wheel pass through the sensor by generating a signal understood by the ECU. So this signal can be utilized to synchronize fuel injection & ignition timing by ensuring the engine works efficiently.

Components

The crankshaft position sensor has different components like a toothed wheel (or) reluctor ring, a stationary sensor like optical or magnetic & associated electronic circuitry, which are explained below.

Toothed Wheel or Reluctor Ring

This is a ring or wheel that has evenly spaced teeth (or) indentations mounted above the crankshaft. When the crankshaft turns then these teeth will pass through the sensor.

Stationary Sensors

Generally, this sensor includes stationary sensors like magnetic, hall effect, and optical, which are explained below.

Magnetic Sensors

Magnetic sensors utilize a magnet & a coil. Whenever the toothed wheel turns then the teeth disrupt the magnetic field, which causes a change in the voltage of the coil. After that, it will be transmitted to the ECU.

Hall Effect Sensors

These types of sensors utilize a Hall-effect chip that produces a voltage output that is proportional to the strength of the magnetic field. When the crankshaft turns, the teeth pass by the crankshaft sensor, thus, it causes changes within the magnetic field & changes within the Hall effect IC output. After that, it is sent to the ECU.

Optical Sensors

These sensors utilize a light emitter & a light receiver. When the toothed wheel turns, the teeth will disrupt the light path, transmitting data on the position of the crankshaft to the ECU.

Electronic Circuitry

Electronic circuitry processes the sensor signal and sends it to the ECU by ensuring the ECU gets a clear and precise signal regarding the crankshaft’s position.

Crankshaft Position Sensor Circuit

The crankshaft position sensor circuit diagram is shown below.

The power of the crankshaft position sensor is provided from terminal no-9 of ECM. The sensor’s terminal-2 is grounded with terminal no-24 of ECM.

A 5V supply is provided on terminal no or sensor output terminal from the terminal no of ECM. So this sensor produces a pulse signal whenever the output terminal is opened & grounded.

Working

The crankshaft position sensor notices the crank angle or position of every cylinder and changes that data to pulse signals, after that which are input to the ECM. Whenever the engine is running, the crankshaft position sensor provides a pulse output signal. The ECM verifies whether the pulse signal is input when the engine is cranking.

Types of Crankshaft Position Sensors

Crankshaft position sensors are available in different types like inductive, optical, magnetoresistive element, and Hall-effect which are explained below.

Inductive Sensors

An inductive sensor is also known as a variable reluctance sensor that uses a magnet to detect teeth or notches above a toothed wheel connected to the harmonic balancer or crankshaft. Whenever the teeth pass the camshaft sensor, they create a changing magnetic field to generate a voltage signal. These types of sensors are simply passive devices.

Hall-Effect Sensors

Hall effect sensors utilize the Hall effect, where a magnetic field causes a voltage supply to emerge across a semiconductor material. So they normally need a power supply & output a DC square wave that indicates whether a tooth is below the sensor (or) not. These can notice static magnetic fields like inductive sensors.

Magnetoresistive Element Sensors

These sensors utilize a magnetoresistive element that changes its resistance in response to a magnetic field so they can notice static magnetic fields.

 

Optical Sensors

Optical sensors utilize an LED (light-emitting diode) and a photodiode to notice optical slots or marks on a rotary shaft or disk. They provide higher precision and are appropriate for both low-speed and high-speed applications. But they need a clean optical lane for precise readings.

How to Test a Crankshaft Position Sensor with a Multimeter?

The step-by-step procedure to test a crankshaft position sensor using a multimeter is discussed below.

Disconnect CKP Sensor

• Need to detach the sensor from the car to remove interference from different components.
• Place the CKP sensor, normally found close to the flywheel or crankshaft pulley.
• Detach the sensor very carefully from the electrical connector. So, based on your car model, we have to eliminate a protective cover or utilize a tool to discharge the connector.

Arrange the Multimeter

• To test the CKP sensor, you’ll need a multimeter capable of measuring resistance, voltage, and other electrical parameters. Follow these steps to set up your multimeter:
• Set the multimeter to resistance or ohm (Ω) mode for measuring sensor resistance.
• Connect the multimeter leads to the suitable terminals of the CKP sensor.

Resistance Testing

• The CKP sensor resistance checking indicates its proper working.
• First, multimeter leads need to be connected to the terminals of the CKP sensor.
• After that, observe the multimeter reading so resistance values will change depending on the CKP sensor & air temperature.
• Evaluate the measured resistance to the particular range. If it drops in the suggested range, then the sensor may be defective and must be changed.

Voltage Testing

• The voltage output needs to be tested for the sensor to ensure it produces the right signal.
• First, the multimeter needs to be set to voltage mode.
• After that, its leads must be connected to the terminals of the CKP sensor.
• Begin the engine to simulate engine revolution.
• Monitor the multimeter reading.
• If the voltage output reading is outside the fixed range, then the sensor may be defective and needs replacement.

Ensure for Damage

• Check the CKP sensor for any visual injuries like corrosion, loose connections, cracks, etc. If the injury is obvious, then replace the sensor.
• Reconnect the CKP Sensor
• Once testing is done, reconnect the sensor to the wiring harness of the vehicle:
• Align the electrical connector through the sensor terminals.
• Gently thrust the connector into position until it locks or clicks.
• Make sure the connector is strongly attached to the CKP sensor.

How to Reset the Crankshaft Position Sensor without a Scanner?

When a scanner is usually suggested to test a crankshaft position sensor, then a temporary fix must be tried by restarting the car engine for a moment to carry the performance metrics back into balance for engines.

Understanding the Problem

The CKP sensor helps the ECU of the car to determine the timing & other performance metrics of the engine. So these metrics can turn into imbalanced if there is a computer breakdown.

A scanner generally allows for a more exact & thorough reset or relearn process by ensuring the sensor is correctly calibrated to the specific parameters of the vehicle.

Temporary Fix Without Scanner

The engine must be restarted even for some moments, which can sometimes provide an effective reset that brings the metrics back into balance.

Drive around at a stable speed, and after that, stop the car but don’t leave it within neutral.
Allow your vehicle to be inactive for some time to let the sensor relearn.

Crankshaft Position Sensor Vs Camshaft Position Sensor

The difference between the crankshaft position sensor and the camshaft position sensor include the following. The crankshaft position sensor detects the crankshaft’s speed and position, whereas the camshaft position sensor tracks the camshaft’s position. So, both the sensors are significant for appropriate engine operation and ignition or fuel timing.

Crankshaft Position Sensor	Camshaft Position Sensor
The Crank position sensor is generally placed in the crankcase above the toothed wheel of the crankshaft.	The Camshaft position sensor is generally placed in line through the toothed wheel above the camshaft end.
It monitors crankshaft revolution and TDC (top-dead-center) position	This sensor monitors the camshaft revolution & valve position.
This sensor provides the ECU (Engine Control Unit ) with the necessary data for fuel injection timing, engine speed calculations & ignition timing,.	It helps the ECU synchronize fuel injection & ignition timing through the specific cylinder firing order & valve timing.
This sensor is can be found close to the flywheel (or) crankshaft pulley, frequently in the timing cover (or) near the base of the engine block.	It is located close to the camshaft (or) camshaft pulley, frequently on the head of cylinder otherwise timing cover.
Essential for engine starting and smooth operation.	Ensures proper valve timing for efficient engine performance.
The reluctor wheel speed of this sensor is double that of the camshaft reluctor wheel.	The reluctor wheel works at half of the crankshaft speed.
Its engine needs two crankshaft position sensors.	This sensor’s engines need a maximum of four camshaft position sensors.
The crankshaft position sensor falls short because of the electrical issues and overheating.	This sensor fails because of water damage, wear & tear,  etc.

Symptoms

The crankshaft position sensor’s bad symptoms can cause some noticeable issues, which are discussed below.

• The check engine light activation is the primary sign of CPS failure, so the ECU frequently logs a code whenever it notices an issue with the sensor.
• A faulty CPS results in failed or delayed engine starts since the ECU lacks the required data to start combustion properly.
• If the CPS does not work properly while driving a car, then it causes the engine to cut out or stall unexpectedly. So this can be particularly unsafe if you are driving a car at higher speeds.
• Erroneous timing can be caused by a malfunctioning CPS, which leads to misfires or rough idling to make it a less smooth driving skill.
• Without the CPS accurately controlling timing, fuel consumption can increase, causing your car to use more fuel than usual.
• Difficulty in starting (or) stalling the engine while driving a car.
• The engine might idle unevenly, run rough, or face misfires, which can feel like a vibration or stumble.
• A bad crankshaft sensor can lead to inefficient engine running, which results in decreased fuel mileage.
• The vehicle doesn’t go faster and more smoothly.
• When the car engine cranks, the tachometer doesn’t function.
• A faulty crankshaft position sensor in some conditions will cause an engine to stutter, misfire, or even backfire or hesitate.

CPS Failure Causes

The crankshaft position sensor over time is subject to wear and tear, particularly since it is arranged in the engine part that gets exposed to higher temperatures & vibrations. So, CPS might fall short due to some common reasons, which are explained below.

• High engine temperatures can corrupt the components of the sensor eventually, which leads to total failure or intermittent failure.
• Continuous vibrations can loosen the crankshaft sensor or wear down its components, which leads to signal loss.
• Damaged connectors, corroded terminals, or wires can result in poor (or) no signal transmission from the crankshaft sensor to the engine control unit.
• The position of the sensor near the crankshaft will expose it to potential contagion from debris or oil leaks, so this can damage its performance or lead to a whole malfunction.
• The CPS has a limited lifetime & may simply wear out eventually, similar to all engine components.

Replacement

The steps involved in replacing CPS mainly include the following.

• If your crankshaft position sensor is faulty, then replacement is generally the best solution.
• This sensor is generally arranged near the crankshaft, normally at the front side of the engine block or close to the transmission.
• Always separate the battery before functioning on any engine component to keep away from potential electrical problems.
• Based on the position of the sensor, other engine components need to be removed to access it. So loosen the mounting bolts & cautiously take away the sensor.
• Locate the new CPS sensor in a similar position and protect it with the mounting bolts. Make sure that all connections are safe to keep away from future problems.
• When the new sensor is connected then reconnect the battery & begin the engine. So, a successful fix will remove any CPS-related problems, like rough idling or stalling.

Advantages & Disadvantages

The advantages of crankshaft position sensors include the following.

• Accurate ignition timing & fuel injection:
• Optimized performance of the engine
• It has improved fuel efficiency
• Less harmful emissions:
• Engine operation is smoother.
• Detection & prevention of misfires.
• Start-stop functionality and regulatory compliance.

The disadvantages of crankshaft position sensors include the following.

• Difficulty in starting.
• Engine stalling.
• Rough idling or misfires.
• Reduced fuel efficiency.
• Engine performance issues.
• Engine stalling occurs unexpectedly due to wiring issues
• Rough idling or misfires.
• Fuel efficiency can be reduced.
• Inaccurate signals from the sensor can lead to a sluggish acceleration or lack of power.
• A faulty sensor can activate the check engine light to specify trouble that must be addressed.
• Changing a faulty sensor can be expensive.
• These sensors are easily exposed to harsh engine circumstances.
• This sensor can become infected by grime, debris, oil, etc.
• Damaged wiring can disturb the signals transmitted from and to the crankshaft sensor, which causes malfunction.

Applications

The applications of crankshaft position sensors include the following.

• The CKP sensor precisely measures the position & speed of the crankshaft; thus, it is significant for appropriate engine operation.
• The ECU utilizes the sensor data to control the spark plug timing exactly by ensuring optimal combustion.
• This sensor’s data can help the ECU to decide the accurate amount and fuel injection timing for clean and efficient combustion.
• This sensor supplies the ECU with a consistent RPM reading, thus, it is essential for a variety of engine functions.
• The CKP sensor contributes to decreasing harmful emissions by precisely controlling fuel injection & ignition.
• This sensor is essential for starting & maintaining the operation of the engine.
• This sensor can be used to detect the position & speed of the engine with stop/start technology.
• It detects engine misfires, which increases engine damage & emissions.

Thus, this is an overview of the crankshaft position sensor, its working, and its applications. This is a significant engine component used to detect the position & speed of the crankshaft by providing necessary data to the ECU (engine control unit) for ignition timing & optimal fuel injection. It ensures smooth engine operation and avoids stalling or misfires. Here is a question for you: What is a camshaft position sensor?