Home » Guides » Discover the Need for Speed: How to Test a Speed Sensor with a Multimeter?

Discover the Need for Speed: How to Test a Speed Sensor with a Multimeter?

By shafiq usama

How to Test a Speed Sensor with a Multimeter?

As an electrical engineer, I love explaining how things like circuits and electronics work. I write on my blog to share simple explanations, reviews, and useful tips about the latest technology.

In today's fast-paced world, accurate speed measurements are crucial for the smooth functioning of various industries and applications. Speed sensors are vital in monitoring rotational or linear speeds, ensuring optimal performance in vehicles, machinery, and other systems. Are you know how to test a speed sensor with a multimer? If not, then this short guide is for you.

  • First, locate the speed sensor near the transmission or wheel hub. 
  • Next, set your multimeter to the resistance or ohms setting.
  • Disconnect the sensor's electrical connector and attach the multimeter's probes to the sensor's terminals.
  • Rotate the wheel or drive the vehicle to generate a signal.
  • The multimeter should display a resistance value within the sensor's specified range. 

If the reading is outside the scope or shows an open circuit, it indicates a faulty speed sensor that needs replacement. If you want to know more in details let's have get started.

Safety should be your top priority when testing a speed sensor with the help of a multimeter. First, you should understand the speed sensor, how it works, and its importance. So, let’s go to the learning:


What are Speed Sensors?

Speed sensors are electronic devices that measure how fast an object rotates or moves in a linear direction. They are widely used in automotive, aerospace, manufacturing, etc. Depending on the sensor type, these sensors detect changes in magnetic fields, electrical currents, or light patterns. By converting speed into electrical signals, they provide valuable data for controlling and monitoring systems.


Types of Speed Sensors

Speed sensors come in different forms, each with advantages and applications. Here I will explain three prime types of speed sensors. Don’t waste time; let’s go to the types:

1-Hall Effect Sensors

Hall effect sensors use the Hall effect principle to measure speed. They consist of a semiconductor material that generates a voltage when subjected to a magnetic field. As the rotating or moving object passes by the sensor, the magnetic field changes, causing the sensor to produce an electrical signal proportional to the speed.

2-Inductive Sensors

Inductive sensors utilize electromagnetic induction to detect speed. They consist of a coil and a metal target. As the target moves, it induces changes in the coil's magnetic field, generating an electrical signal. These sensors are commonly used in proximity applications and have excellent reliability.

3-Optical Sensors

Optical sensors employ light beams to measure speed. They consist of a light source, a detector, and an interrupter or reflective surface. When the rotating or moving object interrupts or reflects the light beam, the sensor detects the change, producing an electrical signal. Optical sensors offer high precision and are often used in applications requiring accurate speed measurements.


Gathering the Necessary Tools

You should gather the necessary tools before knowing how to test a speed sensor with a multimeter. Having the right equipment ensures a smooth testing experience and accurate results. Let's review the essential tools for testing speed sensors with a multimeter.

Multimeter

how to test a speed sensor with a multimeter

The multimeter is the primary tool for testing speed sensors. It is a versatile device that combines various measurement functions in one unit, including voltage, resistance, and continuity. Make sure you have a multimeter compatible with the electrical characteristics of the speed sensor you're testing. It should also have appropriate ranges for voltage and resistance measurements.

Read more about 5 best multimeter with millivolts option 

Probes

Probes are the connecting cables that come with the multimeter. They have sharp, pointed tips for securely contacting the electrical terminals of the speed sensor. Ensure your multimeter has suitable probes that can easily reach the sensor's connectors and provide reliable readings.

Safety Equipment

Safety should always be a priority when working with electrical systems. Before testing the speed sensor, make sure you have the following safety equipment:

  • Protect your eyes from any potential debris or sparks during testing.
  • Insulated gloves provide an additional layer of protection against electrical shocks.
  • Wear clothing that minimizes the risk of electrical accidents, such as long sleeves and non-conductive materials.
  • Place a non-conductive mat underneath your work area to prevent accidental short circuits or damage to sensitive components.
  • Consult the manual specific to your equipment or vehicle to ensure you follow the manufacturer's recommended procedures. The manual may contain valuable information on locating the speed sensor, identifying its connectors, and any additional precautions or guidelines to be aware of during the testing process.

Learn How to test a speed sensor with a multimeter? Just in 7 easy steps 

Following these steps, you can accurately assess the sensor's functionality and identify potential issues. Let's get started!

Step#1 Locating the Speed Sensor

how to test a speed sensor with a multimeter

Consult the equipment or vehicle manual to determine the exact location of the speed sensor. It may be on the transmission, wheel hub, or other relevant parts. Familiarize yourself with its position before proceeding.

Step#2 Accessing the Speed Sensor

Depending on the sensor's location, you might need to remove covers or panels to gain access. Use appropriate tools and techniques to remove any necessary components safely. Take care not to damage surrounding parts or wiring during this process.

Step#3 Identifying the Speed Sensor's Electrical Connectors

Locate the electrical connectors of the speed sensor. They are typically small and have wires connected to them. Take note of the connector's shape, size, and number of wires attached. This information will be essential for the testing process.

Step#4 Disconnecting the Speed Sensor

Gently disconnect the electrical connectors from the speed sensor. Pay close attention to any locking mechanisms or tabs needing release. Take care not to pull on the wires while disconnecting.

Step#5 Setting up the Multimeter

Set your multimeter to the appropriate settings for voltage or resistance measurement, depending on the type of speed sensor you're testing. Refer to the multimeter's user manual if needed. Choose a suitable range for accurate readings.

Step#6 Testing the Speed Sensor's Electrical Signal

With the multimeter adequately set up, touch the probes to the electrical contacts of the speed sensor. If the sensor has multiple wires, consult the manual or wiring diagram to identify the correct connections to test. The multimeter will display the readings of voltage or resistance.

Step#7 Interpreting the Test Results

Compare the multimeter readings with the expected voltage or resistance values specified in the equipment or vehicle manual. If the readings deviate significantly from the expected values, it indicates a potential issue with the speed sensor or its wiring. Document the tasks for further analysis and troubleshooting.

Read more about How to test AGM battery with multimeter

Troubleshooting Speed Sensor Problems

Even with regular testing, speed sensors can encounter issues that affect their performance. This section will explore expected speed sensor problems and provide troubleshooting steps to help you identify and resolve them. 

No Signal or Erratic Readings

how to test a speed sensor with a multimeter

If your multimeter displays no signal or erratic readings when testing the speed sensor, there might be a few potential causes:

Wiring Issues

Inspect the wiring connected to the speed sensor. Look for any loose connections, frayed wires, or damaged insulation. Repair or replace any faulty wiring.

Sensor Alignment

Check the alignment of the speed sensor with the rotating or moving component it monitors. Ensure it is correctly positioned and secured. Adjust the sensor if necessary.

Sensor Damage 

Examine the speed sensor for physical damage, such as cracks or broken components. Replace the sensor if any visible damage is detected.

Inconsistent Readings

If you're getting inconsistent readings from the speed sensor, consider the following troubleshooting steps:

Contamination

Clean the speed sensor and its surroundings to remove any dirt, debris, or buildup that might affect its performance. Use a suitable cleaning agent and a soft cloth.

Magnetic Interference 

Magnetic interference from nearby components or magnets can disrupt the speed sensor's operation. Identify and eliminate any sources of magnetic interference.

Sensor Power Supply 

Ensure that the speed sensor receives the appropriate power supply. Check for voltage drops or inadequate power delivery. Address any power-related issues accordingly.

Read more abut How to test power supply with multimeter
Sensor Failure

If the speed sensor consistently fails to provide any readings or exhibits complete malfunction, you may need to take the following actions:

Sensor Replacement

If all troubleshooting attempts fail, it might be necessary to replace the speed sensor. Consult the equipment or vehicle manual for the correct replacement part.

Professional Assistance

In complex systems or situations where you need clarification about the troubleshooting process, you should seek professional assistance from a qualified technician or service center.


FAQs about how to test speed sensor with a multimeter

How do you check if a speed sensor is bad?

Well, it's easier than you might think! Inspect the wiring and connectors for any visible damage or loose connections to check if a speed sensor is bad. Next, grab a multimeter and measure the resistance of the speed sensor. Every vehicle has a specific range of ohm readings the manufacturer provides, so compare your assignment to that range. 

Read more about 5 symptoms of bad sensor

If the ohm reading falls outside the specified range, it strongly indicates a faulty speed sensor. By following these simple steps, you can quickly assess the condition of your speed sensor and take appropriate action to ensure your vehicle is running smoothly.

What is the ohm reading of the speed sensor?

When it comes to speed sensors, understanding the ohm reading is crucial. The ohm reading of a speed sensor can vary depending on the make and model of the vehicle. It's essential to refer to the manufacturer's specifications to determine the specific range of ohm readings for your particular speed sensor. A healthy speed sensor typically displays an ohm reading within this specified range. 

By measuring the resistance using a multimeter and comparing it to the manufacturer's guidelines, you can quickly assess whether your speed sensor is functioning correctly. Remember, each vehicle may have unique ohm reading requirements, so it's essential to consult the appropriate documentation or contact a qualified technician for accurate information.

How do you test a 3-wire speed sensor?

Testing a 3-wire speed sensor is a relatively straightforward process. To begin, ensure the ignition is turned on. Locate the signal, ground, and power wires of the speed sensor. Using a multimeter, connect the leads to the signal and ground wires. Now, manually rotate the wheel attached to the speed sensor. 

As you rotate the wheel, observe the multimeter's display. A healthy 3-wire speed sensor should produce a fluctuating voltage reading on the multimeter, indicating it functions correctly. This fluctuating voltage corresponds to the sensor detecting the wheel's rotational movement. Learning how to test a 3-wire speed sensor is also essential, as well as how to test a speed sensor with a multimeter. 

Final thought

Learning how to test a speed sensor with a multimeter is crucial for ensuring accurate readings, preventing costly repairs, optimizing performance, and maintaining a safe working environment. Regular testing helps identify faulty sensors early on, allowing for timely repairs and preventing potential issues. 

Remember to consult the equipment or vehicle manual for specific instructions and guidelines. By incorporating regular testing into your maintenance routine, you can ensure the reliable operation of speed sensors and contribute to the smooth functioning of various systems.