Unleash The Power Of Your Car's Engine: How To Check Crankshaft Sensor With Multimeter

Key points

The crankshaft sensor is a crucial component in your car’s ignition system, responsible for informing the engine control unit (ECU) about the crankshaft’s position and speed.
With the ignition key in the “ON” position (but not starting the engine), touch one test lead to the sensor’s signal wire and the other to the sensor’s ground wire.
If there is no voltage or the reading is significantly lower than what’s specified in your service manual, the sensor may be faulty or there could be an issue with the wiring.

The crankshaft sensor is a crucial component in your car’s ignition system, responsible for informing the engine control unit (ECU) about the crankshaft’s position and speed. A malfunctioning crankshaft sensor can lead to various issues, including difficulty starting, misfires, and even engine stalling. Knowing how to check the crankshaft sensor with a multimeter can save you time and money by allowing you to diagnose the problem yourself before seeking professional help. This blog post will guide you through the process, step by step.

Understanding the Crankshaft Sensor

The crankshaft sensor is a small, magnetic device typically mounted near the crankshaft pulley. It consists of a magnetic pickup coil and a toothed wheel. As the toothed wheel rotates, it interrupts the magnetic field generated by the pickup coil, creating a series of electrical pulses. These pulses are then sent to the ECU, which uses them to determine the crankshaft’s position and speed.

Common Symptoms of a Faulty Crankshaft Sensor

Before diving into the testing procedure, it’s essential to understand the common symptoms that indicate a potential issue with your crankshaft sensor. These include:

Difficulty starting: The engine may crank but fail to start or take an unusually long time to ignite.
Misfires: The engine may run roughly, with noticeable misfires or stumbling.
Engine stalling: The engine may stall unexpectedly, especially at idle or during acceleration.
Check Engine Light (CEL): A malfunctioning crankshaft sensor will often trigger the CEL, accompanied by a specific diagnostic trouble code (DTC).

Gathering the Necessary Tools

To check your crankshaft sensor with a multimeter, you’ll need the following tools:

Multimeter: A digital multimeter is highly recommended for accurate readings.
Test leads: A set of test leads compatible with your multimeter.
Service manual: A service manual for your specific vehicle will provide detailed information about the crankshaft sensor location, wiring diagram, and specifications.
Safety glasses: Always wear safety glasses when working around automotive components.

Locating the Crankshaft Sensor

The location of the crankshaft sensor varies depending on the vehicle model. Refer to your service manual for precise instructions. Typically, it’s found near the crankshaft pulley, often on the front of the engine. It may be easily accessible or require some components to be removed for access.

Disconnecting the Crankshaft Sensor

Once you’ve located the crankshaft sensor, carefully disconnect the electrical connector. Make sure to disconnect the negative battery terminal before proceeding to prevent electrical shocks.

Checking the Sensor’s Resistance

With the sensor disconnected, set your multimeter to the ohms (Ω) setting. Touch one test lead to the sensor’s signal wire and the other to the sensor’s ground wire. The resistance reading should fall within the specifications provided in your service manual. If the reading is outside the acceptable range, the sensor is likely faulty.

Checking the Sensor’s Voltage

With the sensor still disconnected, set your multimeter to the voltage (V) setting. With the ignition key in the “ON” position (but not starting the engine), touch one test lead to the sensor’s signal wire and the other to the sensor’s ground wire. You should see a small voltage reading. If there is no voltage or the reading is significantly lower than what’s specified in your service manual, the sensor may be faulty or there could be an issue with the wiring.

Checking the Sensor’s Output Signal (Optional)

This step requires a bit more technical expertise and involves using an oscilloscope to check the sensor’s output signal. If you have an oscilloscope, you can connect it to the sensor’s signal wire and observe the waveform as you rotate the crankshaft. A healthy sensor will produce a clean, square-wave signal. If the signal is distorted or absent, the sensor is likely faulty.

Replacing the Crankshaft Sensor

If your multimeter test indicates that the crankshaft sensor is faulty, you’ll need to replace it. Refer to your service manual for instructions on how to remove and install the new sensor. Ensure the new sensor is compatible with your vehicle and is properly connected.

The Importance of a Proper Diagnosis

It’s important to remember that a faulty crankshaft sensor isn’t the only possible explanation for the symptoms mentioned earlier. Other components, such as the ECU, wiring harness, or even the ignition system, could be the culprit. Therefore, a proper diagnosis is crucial before replacing any parts.

Final Thoughts: Beyond the Sensor

This guide has provided you with a comprehensive understanding of how to check your crankshaft sensor with a multimeter. While this knowledge can be invaluable for diagnosing engine problems, remember that automotive repair can be complex. If you’re unsure about any aspect of the process or encounter unexpected results, it’s always best to consult a qualified mechanic for professional assistance.

Unleash the Power of Your Car’s Engine: How to Check Crankshaft Sensor with Multimeter