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How to Test a Crankshaft Position Sensor (Step-by-Step)

Updated: Jan 8

The crankshaft position sensor, also known as the engine speed sensor, is an important component in your vehicle's ignition system.


It is responsible for monitoring the position and rotational speed of the crankshaft, and sending this information to the engine control module (ECM).


If the crankshaft position sensor is not functioning properly, it can cause issues with your vehicle's ignition timing, fuel efficiency, and overall performance.


In this guide, we will show you how to test a crankshaft position sensor step-by-step to determine if it is functioning correctly. Before beginning, make sure to gather the necessary tools and materials, and refer to your vehicle's service manual for specific instructions and safety guidelines.

 

Table of Contents:


a multimeter

What a Crankshaft Position Sensor Is

A crankshaft position sensor is a device that is used to determine the position and rotational speed of the crankshaft in an internal combustion engine. These sensors are typically located on the engine block, and are used to monitor the rotational position of the crankshaft as the engine runs.


Crankshaft position sensors work by detecting the movement of the crankshaft as it rotates. They do this by using a variety of different techniques, such as inductive sensing, Hall effect sensing, or optical sensing.


When the crankshaft position sensor detects movement, it sends a signal to the engine control unit (ECU), which uses this information to adjust the timing of the ignition and fuel injection systems.


The main function of a crankshaft position sensor is to provide the ECU with accurate and timely information about the position of the crankshaft. This information is used to optimize the performance of the engine, and to ensure that it is running smoothly and efficiently.


In addition to its role in engine management, the crankshaft position sensor is also used in a variety of other automotive systems, such as transmission control, stability control, and traction control. So, it is a very important component of a vehicle.


diagram of how a crankshaft position works

Types of Crankshaft Position Sensor

There are two main types of crankshaft position sensors that are commonly used in vehicles.


  • Inductive (magnetic)

  • Hall-effect


Inductive (Magnetic) Crankshaft Sensor

An inductive crankshaft sensor is a type of magnetic sensor that is used to determine the position of the crankshaft. These sensors typically have one or two wires, and are mounted in front of a rotor or reluctor wheel.


When the sensor is triggered, it produces its own AC voltage signal, which can be used to determine the position of the crankshaft.


Hall-Effect Crankshaft Sensor

A Hall-effect crankshaft sensor is a type of digital sensor that uses the Hall effect to determine the position of the crankshaft. These sensors typically have three or four wires, and are also mounted in front of a rotor or reluctor wheel.


When the sensor is triggered, it generates a digital (square wave) signal, which can be used to determine the position of the crankshaft.


Unlike inductive crankshaft sensors, Hall-effect sensors require an outside power source and a ground connection in order to produce their signal.


How to Test an Inductive Type Crankshaft Position Sensor

To test an inductive type crankshaft position (CKP) sensor, follow these steps as an example. Note that some manufacturers include a protective shield on the sensor's wiring, under the insulation, to prevent electrical interference.


It is also possible that your vehicle may have a third wire on the harness connector.


Be sure to refer to your vehicle repair manual for the electrical value specifications and any recommended testing procedures specific to your vehicle model. It is important to follow the manufacturer's guidelines to ensure accurate and safe testing of the crankshaft sensor.


You will need a digital multimeter to complete the testing.


To prevent the engine from starting during the testing process, you can take the following precautions.


  • Disable the fuel system by removing the fuel pump fuse or relay.

  • Disconnect the ignition cable between the ignition coil and distributor.


It is always a good idea to consult your vehicle repair manual for specific instructions on disabling the engine for your particular vehicle model. These steps will ensure that the engine remains off while you are conducting the crankshaft position sensor test.


To test the crankshaft position sensor, follow the steps below.


  1. Unplug the crankshaft sensor electrical connector.

  2. Set your digital multimeter to the DC voltage scale on a low range.

  3. Turn the ignition key to the "On" position, but do not start the engine.

  4. Touch the black lead of the multimeter to a grounded surface, such as a clean spot on the engine, a metal bracket, or the negative (-) post of the battery.

  5. Touch the red lead of the multimeter to each of the sensor wires on the unplugged connector. One of the wires should produce around 1.5 volts. If it does not, the sensor is not receiving a reference voltage and needs to be fixed.

  6. Set your digital multimeter to the AC voltage scale on a low range.

  7. Connect the meter leads to the sensor pins, making sure to keep the lead wires away from any moving engine parts.

  8. Have an assistant crank the engine for a few seconds while you observe the meter's readout. The sensor should produce a voltage pulsing signal. If no voltage pulses are present, the sensor should be replaced. If your multimeter has a frequency (Hz) setting, you can use this in the same way to check for an AC signal. Compare your results to the manufacturer's specifications as listed in your vehicle repair manual.


How to Test a Crankshaft Position Sensor Resistance

To check the resistance of your induc