Subaru Wheel Speed Sensor Problems? The 7 Latest Answer

Wheel speed sensors, also known as ABS sensors, monitor the speed of the wheels. These sensors constantly monitor the speed of rotation of the wheel and send it to the ABS control module. Because they play a functional role in control parameters, wheel speed sensors are an important automotive component that needs to be well maintained.

In order to ensure the effective functioning of ABS, there are different types of wheel speed sensors. Everyone has an important role to play. Today we are going to look at these types and their functions to better understand how ABS works.

Wheel speed sensors or ABS sensors

The ABS sensors are also referred to as wheel speed sensors

The wheel speed sensors are also referred to as ABS sensors or ABS brake sensors. Wheel speed sensors monitor the rotational speed of each tire and report their performance to the vehicle’s engine control module (ECM). In a car, each wheel rotates at a different speed. Based on the data from the sensor, the ECM analyzes whether one of the wheels is locked.

These sensors work closely with the vehicle’s complex electronic systems to ensure proper driving dynamics, reduced fuel consumption and reduced exhaust emissions. The ABS control unit sends the wheel speed information received from speed sensors to various vehicle systems via data lines.

Types of wheel speed sensors – active and passive

Active and passive sensors are two types of wheel speed sensors

There are two types of wheel speed sensors: the active sensor and the passive sensor.

Active wheel speed sensors

Wheel speed sensors categorized as active sensors are very different from passive speed sensors. The active wheel speed sensor is only “activated” when power is supplied and generates an output signal. There is a digital signal generated by active wheel speed sensors that is sent to the ABS control unit.

Active wheel speed sensors are also known as magnetoresistive because they contain a sensor element connected to a magnetic element or a two-pole electrical cable. The active sensor is more efficient than a passive sensor because digital signals are more accurate at slow speeds and can tell which way the wheel is turning.

Passive wheel speed sensors

Passive speed sensors, also called inductive or variable reluctance magnetic sensors, operate without an additional power supply. It sits above the pulse wheel, which is connected to the drive shaft. The sensor detects the speed as the pulse wheel rotates, resulting in a tooth-to-tooth winding change, which in turn creates a change in magnetic flux. The passive sensor generates an AC signal with varying frequencies according to wheel speed, which is then converted to a digital signal by the ABS control unit.

Therefore, the front and rear wheel speed sensors work with or without a defined voltage from the ABS control unit. As a result, the ABS sensors ensure that the car does not skid or skid when braking.

What Causes Wheel Speed ​​Sensors to Stop Working?

Wheel speed sensor of vehicles equipped with electronic active safety systems and auxiliary control systems

Now that we know the types of wheel speed sensors, we know how important they are for a vehicle to function optimally. It is important to understand the causes of faulty wheel speed sensors, to know where to look for damage and to take precautionary measures to avoid the problem.

Heavy contamination or deposits are a major cause of errors. Defective wiring of the speed sensors, which can interfere with signal generation and detection. Since speed sensors also work with voltage, internal short circuits lead to failure. Read here to learn more about the causes of short circuits in a car and solutions. Another reason is driving with increased wheel bearing play. Mechanical damage to the wheel encoder, which detects the rotation of the motor, can affect the wheel speed sensor. Any other external damage can affect the speed sensors.

Things to know about wheel speed sensors

Keep the sensors clean to protect them from damage

Wheels on a car either have rotors or rear drums. The tire containing a rotor also has a speed sensor, while the tire with the rear drum has one rear speed sensor and two front speed sensors. As previously mentioned, you need to keep the sensors free of dirt and debris to avoid malfunctioning. If the sensors remain dirty, they no longer work. In this case, it must be replaced or properly cleaned by the mechanic. There is at least one speed sensor in each wheel. It makes it possible to replace only the one-speed sensor if necessary. Like the ABS control unit, the Traction Control System (TCS) relies on wheel speed sensors. If there is a problem in both systems, replacing the speed sensors can fix it.

What are the signs of faulty wheel speed sensors?

The signs of a bad wheel speed sensor are as follows:

The ABS warning light turns on in the dashboard. The traction control system (TCS) indicator light is on. The wheels lock when braking. Error code is saved. Loss of traction when driving on slippery road conditions

Depending on the wheel type, there can be one to four ABS sensors on each wheel. The wheel speed sensors are crucial for the functioning of a vehicle’s ABS. The two types of wheel speed sensors tell the ABS control unit when to release the brakes.

In addition, if the wheel speed sensors have failed completely, you can replace them. You can easily find wheel speed sensors online at auto accessory and parts stores in the UAE or in a physical store. Now that you know the types of wheel speed sensors, signs of a bad sensor and how to diagnose the fault, make sure when buying a used car in UAE, it has fully working wheel speed sensors.

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What is an ABS speed sensor replacement?

ABS speed sensors monitor wheel speeds and inform the system’s computer to adjust brake pressure on a wheel if it locks up during braking. Most modern vehicles use a four channel system, meaning there is a sensor for each wheel.

If just one ABS speed sensor fails, your entire ABS system is inoperable. If you brake hard in an emergency, your brakes will lock up and you will lose the ability to steer your vehicle away from another car or object. This can be a matter of life or death.

For this reason, a failed ABS speed sensor needs to be replaced as soon as possible. During an inspection, your mechanic will run a diagnostic test to determine which sensors have failed and need to be replaced.

How to replace a faulty ABS speed sensor

Take your vehicle to a licensed and qualified mechanic to have your faulty sensor replaced. Here’s what a mechanic will do to find and replace it:

A diagnostic test will determine which sensors have failed and which tires need to be removed

Your car will be lifted and the tires will be removed

The mechanic will replace the failed sensor with a new, properly working speed sensor

The tire or tires will be remounted and your vehicle will be lowered

Your ABS system will be checked for other problems

Your vehicle will be road tested to ensure the ABS system is online and the sensors are working

How do I know if I need an ABS speed sensor replacement?

You may have a problem with your ABS speed sensors if the ABS warning light comes on when you start your car and stays on as long as the car is running.

If you can do this safely, test your brakes on gravel or ice. If you step on the brake and it shakes violently but you can still steer your car, it means your ABS and speed sensors are working.

If the brakes lock up and you lose the ability to steer, one or more speed sensors may have failed.

How important is it to replace failed ABS speed sensors?

Replacing failed ABS speed sensors is vital to the proper functioning of your ABS system, not to mention your safety.

A well-functioning ABS allows you to brake hard in an emergency and still steer the vehicle, allowing you to maneuver out of harm’s way.

In fact, insurers consider your ABS system (and by extension, your ABS speed sensors) to be so important that they offer discounts to drivers whose vehicles are well equipped.

Conclusion If just one of your speed sensors fails, your entire ABS system will go offline and not function – replace a failed speed sensor as soon as possible.

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Speed ​​Sensors: Ultimate Guide (2021)

Would you like to know more about the speed sensor in your car?

The speed sensor is a small device that tells your car’s speedometer how fast you’re going. It plays a role in your car’s transmission and cruise control systems.

In this article, we cover what a speed sensor is and how it works. Then we look at the symptoms of a faulty speed sensor and how often you should replace it.

Finally, we’ll go through the steps required to replace the sensor and highlight the best way to keep your speed sensors in check.

This article contains:

(Click on a link to jump to a specific section)

Let’s get in right away.

What is a speed sensor?

A vehicle speed sensor (VSS) is a small component mounted on your car’s transmission that tells the car’s onboard computer how fast you’re moving.

It is also known as a wheel speed sensor, transmission speed sensor or output shaft speed sensor.

How does the speed sensor work?

The vehicle speed sensor measures the RPM of the gears in your transmission system. It then converts that measurement into an analog signal or a low-voltage square wave signal and forwards it to electronic control units (ECUs) in your car.

The ECUs, in turn, use this signal to adjust your car’s odometer readings, ABS module, and transmission system.

Your car’s cruise control can also rely on the data generated by the speed sensor. Without them, your car would not be able to maintain a constant vehicle speed.

What are the symptoms of a faulty speed sensor?

Since your car’s odometer readings, transmission systems and cruise control all depend on signals from the speed sensor, you need to make sure it’s working as expected.

If you experience any of these symptoms while driving, you may need to check and replace the vehicle speed sensor:

1. Inconsistent speedometer readings

Most cars rely on signals from the wheel speed sensor to adjust their speedometer readings. A faulty sensor can result in inconsistent or erroneous tachometer readings.

Alternatively, there may be no measured values ​​at all.

This does not mean that your car simply stops working and you can no longer drive it.

However, with a broken speedometer, you have no idea how fast your car is going, which can affect your road safety.

If you notice the speedometer acting strangely, you should have your car checked by a mechanic to look for speed sensor failures.

2. The Check Engine Light will be activated

When the Check Engine Light comes on on your car’s dashboard, it can be due to various reasons such as:

A defective ignition coil or spark plug

A defective injector

A defective thermostat

But it can also signal a defective speed sensor.

With a faulty speed sensor, an electronic control unit in your car may not detect a transmission speed sensor signal. And this error can activate your car’s check engine light.

In such a situation, it is best to take your car to a mechanic for an inspection.

3. Cruise control malfunction

In most cars, the cruise control system depends on the input signals from the transmission speed sensor.

So if you have a faulty speed sensor, you probably won’t be able to activate the car’s cruise control.

Why?

In general, the Powertrain Control Module (PCM) in your car will automatically disable cruise control if it doesn’t get a proper signal from the VSS.

This is because without the transmission of speed sensor data, it is impossible to maintain the constant vehicle speed required for cruise control.

If you notice that the cruise control system is not working in your car, have a mechanic come by to check if you have a speed sensor problem.

4. Hard gear shifting

Without a reliable signal from the transmission speed sensor, the powertrain control module cannot properly shift gears in your transmission system.

What does that mean?

The PCM can cause harsh shifts and affect the timing between shifts.

That’s not all.

If your car uses an automatic transmission, a faulty sensor can also cause serious damage to the mechanical gear tooth profile and other internal components like hydraulic lines, valve bodies, and more.

To be safe, you should have an auto inspection done soon to detect any transmission problems your vehicle may have.

How often should you replace the vehicle speed sensor?

There is no hard and fast rule by which you can predict how long your wheel speed sensor will last.

Unlike a brake light switch or caliper, which can last as long as your vehicle, you can expect your transmission speed sensor to last between 30,000 and 50,000 miles.

However, as with brake pads, the lifespan of your speed sensor also depends significantly on your driving conditions. If the speed sensor is frequently exposed to road salt and other compounds, it will not last as long.

In addition, the following conditions can shorten the life of your vehicle speed sensor:

Improper installation of the speed sensor

Electrical faults in the speed sensor wiring

Damaged tone ring

Defective magnetic speed sensor or inductive sensor coil

Contamination of the speed sensor tip

Separation between transmission speed sensor and electronic control unit

Poor vehicle maintenance

To avoid safety risks, consider having your VSS checked as soon as possible if you notice symptoms such as erratic speedometer readings or a non-functioning cruise control, and have it replaced if defective.

How much does it cost to replace a speed sensor?

The cost of replacing the speed sensor depends on the make and model of your vehicle. It also depends on the type of sensor currently used, such as an optical sensor, a magnetic field sensor (Hall Effect sensor) or some other type.

However, replacing the speed sensor is generally not expensive. It costs no more than other major repairs such as replacing brake lines and master cylinders.

That being said, you will likely have to pay between $225 and $380 to replace the vehicle speed sensor.

To get a more accurate estimate, simply fill out this online form.

How to replace your car’s speed sensor

You can try replacing your car’s wheel speed sensor yourself.

However, we strongly recommend getting help from a qualified technician.

Why?

For starters, you will need several tools and safety equipment to safely perform the vehicle speed sensor replacement.

And that includes:

Tongs

multimeter

scan tool

socket wrench

Mechanical gloves

eye protection equipment

And more

Additionally, if you don’t do the replacement properly, you could end up with a defective speedometer or cruise control system, which can affect your road safety and result in higher repair costs.

It’s always better to take your car to an auto repair shop or have a mobile mechanic come by.

When hiring a mechanic, remember to check that they:

ASE certified

Only use quality replacement parts and tools

Offer you a service guarantee

To give you an idea of ​​what speed sensor replacement typically involves, here is a breakdown of what your mechanic will likely do:

1. Place a drain pan or bucket under the sensor to catch any spilled liquid.

2. Carefully disconnect the vehicle speed sensor from the transmission system.

3. Disconnect the connector between the vehicle wiring and the speed sensor.

4. Use a socket wrench to loosen and remove the faulty speed sensor.

5. Install the new speed sensor and reconnect the wiring.

6. Start the car’s engine and take your car for a test drive to make sure the speedometer, cruise control and transmission shifter work as expected.

But where can you find a qualified mechanic who can perform a proper speed sensor inspection and replacement?

The best way to keep your speed sensor in check: RepairSmith

If you’re looking for an easy way to fix your speed sensor, look no further than RepairSmith, a convenient and portable car repair and maintenance solution.

Here’s why you should rely on RepairSmith for all your speed sensor needs:

Speed ​​sensor replacement can be performed in your driveway, eliminating the need to take your vehicle to an auto repair shop

, so you don’t have to take your vehicle to an auto repair shop All speed sensor repair and maintenance work is carried out using high-quality equipment and spare parts

and you can easily book your speed sensor repair online

Repairing your speed sensor You can save money by taking advantage of our upfront and competitive prices.

. Only ASE-certified, experienced mobile technicians service your vehicle

, Expert service for your vehicle All your repairs come with a 12-month warranty with a range of 12,000 miles

Keep your speed sensor up to date

The vehicle speed sensor is a crucial component that ensures your speedometer, cruise control and transmission are working properly.

If you’re driving around with a faulty speed sensor, you may not know how fast you’re going and may endanger your safety and that of those around you. In addition, you are likely to have a poor driving experience due to harsh and erratic gear shifts.

To prevent this from happening, have a mechanic inspect your wheel speed sensor and perform a replacement if necessary.

Luckily, RepairSmith makes hiring mobile technicians easier than ever!

All you have to do is fill out an online form and certified mobile mechanics will come to your driveway to perform the speed sensor inspection and replacement.

So if you are looking for a hassle-free and accessible repair service for your speed sensor needs, contact RepairSmith today!

Most modern vehicles have anti-lock braking systems (ABS). This system consists of valves, a controller and a speed sensor, all working together to ensure you can brake safely.

The ABS speed sensor monitors the way the tires are spinning and ensures that the ABS system is triggered if there is a difference or slippage between the wheels. When this sensor detects a difference, it sends a message to the controller telling it to turn on the ABS and override your manual braking.

ABS speed sensors are most commonly mounted on the wheels on most modern vehicles. This is the most efficient place to mount them. Some older vehicles, particularly live axle trucks, have these mounted on the rear differential. The ABS speed sensor is just a magnetic sensor that induces a voltage when the tone ring slots or ribs pass the sensor’s magnetic field. This type of sensor is used for many different systems in a modern car. A sensor of this type can be mounted on anything that rotates to allow the Powertrain Control Module (PCM) to monitor its rotation.

If the ABS speed sensor fails or does not work properly, you can replace it yourself.

Part 1 of 5: Find the right ABS sensor

Materials needed

Step 1: Determine which sensor has failed. Use the scan tool and read the code to determine which sensor has failed. If no code is displayed, you need to monitor the sensor data with a scanner while driving. If this is not possible, you must test each sensor individually.

Tip: Normally it is not necessary to test every sensor. Usually this is required for early pre-OBD II systems, but not for later models of vehicles.

Step 2: Locate the sensor. Locating the sensor on the vehicle can be challenging on some vehicles and you may need to refer to a repair manual specific to your vehicle. The most common locations for the ABS speed sensor are on a wheel or on an axle.

Step 3: Test each sensor to determine which has failed. You can skip this step if the other methods were successful.

Consult your vehicle’s specific repair manual to determine the specifications for the speed sensors on your car.

Part 2 of 5: Remove the speed sensor

Step 1: Gain access to the sensor. Often you will need to remove a wheel or mount to gain access to the sensor. This depends on the vehicle and the sensor to be replaced.

Step 2: Remove the sensor. After accessing the sensor, disconnect the connector and remove the single screw that secures the sensor.

Tip: When removing the sensor from its mount or housing, you may need to apply a small amount of penetrant. Once you have applied the penetrant, twist the sensor to loosen it. Be gentle and patient. Once it begins to rotate, pull the sensor up slowly and firmly. You can often help with lifting with a slotted screwdriver.

Step 3: Make a note of the sensor cable routing. Be sure to note the correct sensor cable route as it is critical that the sensor cable is routed correctly. Otherwise, the wiring will be damaged and the repair will fail.

Part 3 of 5: Clean the sensor mounting hole and tone ring

Step 1: Clean the sensor mounting hole. Before installing the sensor, use some sandpaper and brake cleaner to clean the sensor mounting hole.

Step 2: Clean the tone ring of all fine metal. The ridges on the toner ring often collect fine metal present in the dirt. Be sure to remove all that fine metal.

Part 4 of 5: Install the sensor

Step 1: Prepare to install the sensor. Before installing the sensor, apply a small amount of Sil-Glyde to the sensor o-ring.

Tip: The o-ring will most likely break and be difficult to install if grease is not applied to it. Sil-Glyde is recommended as the first choice, but other lubricants can be used. Just make sure you’re using grease that’s compatible with rubber. Some greases will damage the rubber and using these will expand the rubber o-ring and render it unusable.

Step 2: Insert the sensor into its mounting hole. Be sure to insert the ABS speed sensor with a twisting motion. Once you’ve cleaned the mounting hole, it should slide in easily.

Tip: Do not force the sensor if it does not slide in easily. If the sensor doesn’t install easily, compare the old ABS speed sensor to the new one to see what’s wrong.

Step 3: Route the sensor cable the right way. Make sure the wire is attached along the correct path. Otherwise the cable will likely be damaged and you will have to start over with a new sensor.

Step 4: Connect the sensor connector to the vehicle connector. Listen for an audible click, indicating the connector is locked. If you don’t hear an audible click, try disconnecting the connector without releasing the locking mechanism. If you cannot pull it apart, it is properly attached.

Tip: Be sure to check the electrical connection in the connector on both the vehicle side and the sensor side. It is common for pins like this to be pushed in when the connector is installed. If you suspect this might be happening you will need to unplug the connector to check the small pins.

Part 5 of 5: Clear the code and test drive your vehicle

Step 1: Clear the code. Plug in the scan tool and clear the code. After clearing the code, navigate to the data for the sensor you just replaced.

Step 2: Test drive the car. Take the car for a test drive at speeds in excess of 35 miles per hour.

Monitor the data to ensure the sensor is sending the correct information to the Powertrain Control Module (PCM).

Make sure you are safe while driving and monitoring data. Ideally, ask someone to watch the data for you.

It’s very common to accidentally swap out the wrong sensor, especially when you’re working on a car with sensors on each wheel. To ensure you are replacing the correct sensor, use the multimeter to test the sensor you suspect is defective before removing it.

If you need assistance completing this process, contact a Vermin-Club certified technician to replace the ABS speed sensor for you. Ask him to do a detailed inspection if the ABS light is still on.

Hello, the speed sensor for the speedometer is located on the gearbox on the tail boom housing. The housing is the part where the driveshaft slip yoke (front part of the driveshaft) would be positioned.

The sensor is fixed with a screw that needs to be removed, it has a two-wire connector. After removing the screw, grasp the sensor and pull outward. There is an o-ring seal on top of the sensor to prevent leakage and offers some resistance when removed.

To install a new sensor, lubricate the o-ring seal and press in, align the bracket, and install the screw. No additional setup is required for this sensor.

If you need help with this, consider Vermin Club as one of our mobile technicians can come to your home and replace your speed sensor at your convenience.

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There is no way to quickly determine if a wheel speed sensor (WSS) is passive or active. Both sensors have two wires and are located in the same place on the vehicle. Often the service information does not indicate what types of sensors are present on the vehicle. Error codes do not indicate whether the sensors are passive or active.

Click here to read more

Passive wheel speed sensors

Passive wheel speed sensors are often referred to as “old school” or traditional wheel speed sensors. These are the older versions of wheel speed sensors that need to be understood before moving on to newer active sensors.

Passive WSS are two-wire permanent magnet sensors. The sensors output an alternating current (AC) voltage generated when a toothed toroidal ring or reluctor passes the sensor. The ABS module monitors the change in frequency and amplitude during wheel rotation. A sensor may not read 0 mph but 3-5 mph; that is normal. However, if you are experiencing unwanted activation at low speeds, using a scan tool may not be the best method. Don’t settle for those low speeds; further testing is required.

The graphical representation of the WSSs can be done with a scan tool. You should look for a clean signal from each sensor. All signals should be the same. When the vehicle is stopped, they should all fall off evenly.

When testing a passive WSS, the positive lead of the meter should be connected to the signal lead. The negative terminal should go to ground or chassis ground depending on the test performed.

The sensor and/or harness should be disconnected from the circuit so you are not measuring resistance in the ABS unit. The typical reading for a passive wheel speed sensor is between 1,000 and 2,500 ohms. This is a normal range for all passive sensors. The specification for active sensors is between 1,000 and 2,500 ohms.

AC voltage

If the meter is set to AC voltage, turn the wheel by hand. The sensor should generate between 0.5 and 1 volt AC. The faster the wheel is spun, the more tension is created.

Passive bias sensors

Some vehicles send a DC voltage to the sensor through the ground wire. The signal rises on the DC signal. This is done so that the sensor can be tested by the ABS system without the vehicle moving. These types of vehicles set WSS codes as soon as the key is turned on. You can delete a WSS code and as soon as the key is turned on, the code will be back immediately.

The ABS computer checks the voltage coming back from the sensor. A high resistance or open circuit can be detected immediately. Often with these systems, the problem isn’t with the sensor, but with the preload that flows through the wiring harness and connectors.

When the signal is viewed on an oscilloscope, the voltage rises above the ground or zero line. This vehicle has a bias voltage of 2.5 volts. To measure this, connect the ground lead to battery ground and the positive lead to the signal lead. Without the wheel turning, you can observe the DC voltage being applied to the circuit.

With the sensor disconnected, connect the positive lead to the signal wire and the negative lead to the other side which is the ground for the ABS module. This voltage comes directly from the ABS module and is between 1.5 and 5 volts. This is the preload from the ABS module. Any voltage outside of the manufacturer specification may indicate a problem with the wiring harness.

Undesirable ABS activations in passive WSS

A little rust under a WSS should never be underestimated. Some rust between the WSS and the knuckle or hub may disturb the air gap between the WSS and the tone ring.

You want to remove the rust and polish the surface. Never grind the surface. This could cause further problems. If removing the corrosion doesn’t solve the problem, you might want to look at the tone wheel. Tone rings or wheels are mounted on axles, constant velocity joints and hubs. Most tone wheels are pressed onto these components.

Corrosion can penetrate between the components and damage the tone ring. The teeth of the tone ring pulse the sensor and create an AC voltage in the sensor. If a tooth is missing or misaligned, it can lead to unwanted ABS activation.

Other electrical outlets can cause interference in the WSS lines. Wiring for the ignition system, charging, and serial data buses can cause interference that can lead to false activations. Some OEMs have even issued TSBs directing technicians to reroute or even shield affected cables.

Active wheel speed sensors

Active WSS use two wires and look like passive wheel speed sensors. Active WSS are used on most newer vehicles as they are more accurate at lower speeds and can detect 0 km/h. In addition, active sensors can even detect whether the vehicle is moving backwards.

Active WSSs emit a digital signal. The signal is a direct current (DC) square wave signal. The signals are different than a camshaft or crankshaft position sensor.

The tone wheel of most active sensors is mounted in the bearing grease seal or within the unitary hub assembly. The tone wheel for an active sensor has magnetic teeth with alternating north and south poles. You can’t see the teeth on these rings. For some bearings, the only way to detect is to pass a small ferrous (magnetically attracted) metal component past the rings. Some bearing manufacturers offer a special tool, but a paper clip should do the trick in a pinch.

The end of an active WSS is typically a flat blade tip mounted next to a tone ring. The tip of the sensor is usually buried in a hub or knuckle.

Anti-lock braking systems are one of the many systems in a vehicle that are all or nothing. This means that like an airbag system, if any part of the system is faulty, the entire function will disable itself in the name of safety.

A lit ABS light, like a check engine light, can indicate a variety of errors. A good starting point for diagnosis is the ABS wheel speed sensors.

Physical sensor damage

Without a scan tool that can read ABS codes, visual inspection is the easiest way to diagnose an ABS light. ABS sensor wiring can be checked from underneath a vehicle parked securely on ramps – you may not even need to remove the wheels. If sensor wires are frayed, corroded, or completely broken, you’ve found the problem.

Dirty sensor

ABS sensors can accumulate ferrous deposits or dirt that impairs their ability to read speed information. Removing the sensor is the best way to clean it and in most cases chemicals are not required. If cleaning fails, testing with a multimeter or ABS scan tool is the next step.

Test sensors

If all looks good, it’s still possible that an ABS sensor is failing internally. If an ABS sensor is disconnected, you can use a multimeter to check the terminals so the sensor does not have to be removed from the vehicle. Both passive (2-wire) and active (2- or 3-wire) ABS sensors can be tested for basic functionality with a multimeter. Find out what type of sensor your vehicle has before proceeding.

Most vehicles allow access to the ABS sensor wiring harness in the cab rather than jacking up the car and removing a wheel. For front sensors, check near the inner strut towers – this is where the ABS sensor wires usually enter the engine compartment. For rear sensors, the usual connection points are under the rear seat cushion or in the trunk.

For a passive ABS sensor, measuring the resistance between the signal and ground lines will generally give a reading of 800-2000 ohms. A consistent reading within this range indicates a good sensor. If the resistance on the meter keeps changing or increasing, the sensor is bad. An internal short, a cracked housing, or moisture ingress are just a few reasons why a sensor may have failed.

If the multimeter shows an open (no resistance) or a short, this is another indication that the sensor is defective. A replacement Holsteiner ABS sensor should be purchased prior to removing the defective sensor to keep the vehicle drivable. Holstein sensors correspond in form and function to OE sensors at a lower price than the dealer.

Diagnose and test first

An ABS light can indicate many things, from a pump failure to a dirty wheel speed sensor. A home handyman can save money on parts and labor by establishing a successful diagnosis through proper testing and inspection procedures. Before taking a vehicle to the dealer, consider the do-it-yourself approach – most ABS faults can easily be repaired yourself for a fraction of the price of dealers or independent repairers.