How To Test ABS Sensor? Here’s How To Do It Right!
Are you familiar with ABS sensor? How about testing it? If you have a car, it is important that you are familiar with ABS sensor as anti-lock brakes are among the many systems that are considered to be all-or-nothing.
Why does it matter that you also know how to test it? Well, the same with an airbag system, once one part of the system is at fault, there is an assurance that the entire feature would disable itself. So, how to test ABS sensor?
What Is ABS Sensor? Important Things You Need To Know
But prior to the idea of testing the ABS sensor, you should first know what it is. An ABS or Anti-Lock Braking System is referred as an enhanced braking system that is commonly found in modern automobiles these days.
It is a type of tachometer which measures the rotational speed of the wheel and also passes it to the ECM of the car.
Knowing that all the wheels don’t turn at the same speed, ABS sensors will report the speeds of all the four wheels to the ECM depending on whether the ECM identifies if the wheels are locking up.
When it comes to application, ABS brake is a lot quicker compared to the manual brakes. And because of this, once the ABS is engaged, it would emit a grinding noise in some cars. With the importance of ABS sensor, there is really a need that you test it properly.
Where is it located?
How would you test the said system if you aren’t sure whether where it is located? So, you have to be familiar with the location of ABS sensor.
For the older configurations of the ABS, sensors are located outside the wheel hub within parts like the steering knuckle as well as differential housing. It is also coupled with a ring gear. This ring is also mounted on components like the brake rotor and the brake drum.
On the other hand, for the newer systems, ABS sensors are fitted in the wheel hub assembly itself. Based on the type of the braking system, cars might have as few as one or even up to 4 ABS sensors.
ABS Sensor Mechanism
Of course, knowing the mechanism of ABS sensor should also be considered. The ABS sensor would usually consist a toothed ring and also a ring magnet enclosed in the coil. The contact between them induces an electric field because the signal is generated.
Then this signal will be transformed into a digital signal and will be sent to the ABS controller. This controller will determine the speed of the wheel accordingly.
But bear in mind that these days, later models are indeed equipped with some kind of traction control wherein the ABS sensor is the key to controlling the movement of the car under any conditions.
Once there is a loss of traction, the speed of the wheel on one side would be different from the other one. And this case happens once the on-board computer could regulate the braking power of the car’s wheels and then achieved the desired traction.
And so, the ABS sensor is definitely the main sensor which keeps the braking power of the car that is in check. This sensor will transmit the rotational information to the ECM signal wherein one of the tires is being locked up.
In this case, the computer would lower the amount of braking force being applied to the wheel that is in question. Once the braking force lowers, the wheel could now turn and so regain its grip as well.
Indeed, most of the modern cars have ABS sensors that interact with the electronic traction control systems as well as the stability control systems as for ensuring the safety of your vehicle and yours as well!
Signs Of Failure
And there are certain ABS sensor failure signs that you must also be cautious about. Indeed, over a period of time, exposure to road debris as well as other impurities could lead to failure of the ABS sensor. With this, it is crucial that you clean and inspects the sensors at intervals which are specified in the manuals.
One of the most common indications of a faulty ABS sensor would include the lighting up of the ABS light or the traction control light in the dashboard of the vehicle. The considerable loss of traction once you are driving on slippery road conditions is another symptom of a bad wheel speed sensor.
But always take note that the ABS sensor is not always the culprit rather the connectors or wiring could also go bad which fails to transmit the requisite signals to the ECM. So, prior to checking and also replacing the ABS sensor, it pays that you inspect the related components first or try testing it as well.
Prior to proceeding to the process of testing ABS sensor, you will need the following:
Personal Safety Items
These are the items that will keep you safe from harm once doing the test. These items are as follow:
- Work Gloves. These offer protection or an additional layer of skin avoiding cuts and keeping the grease from getting under the fingernails. It also grips better on metal surfaces.
- Eye Protection. This is a must once working on cars since many items like dirt as well as small pieces of metal which could fly into your eyes once hammering.
- Work Clothes. Indeed, grease and engine grim could ruin normal clothes so it is a great idea to have at least one pair of pants, shoes and shirt once working with cars.
Toolboxes and Tools
It is best that you are complete with tools needed as you test the ABS sensor. It would also be an advantage if the toolbox is complete with all the sets of tools such as the following:
These tools are the specialized tools that are needed as for removing brake springs that are used for the rear brake shoe as well as parking brake shoe replacement. Some other brakes tools include these:
As for lifting the car off of the ground then support it correctly that is a safety issue. The needed sets of equipment are as follow:
And there are numbers of other things needed that should be included such as Fluids, Air Conditioner and Shop Supplies. Though not everything included in this list are to be used during testing the ABS sensor, still it pays a lot that you have a complete set of tools.
But for the most important part, the most important item that you will need is the VOLTMETER. The process that will be provided to you as to how to test ABS sensor will be using voltmeter as the main item.
Voltmeter is referred as an instrument that is used for measuring electrical potential difference in between two points in the electric circuit. So, if you want to test the ABS sensor first, never forget bring voltmeter with you.
How To Test ABS Sensor Using Voltmeter?
Finally, here we are! You will be provided with a guide on how to test ABS sensor. But before you begin, you should first park the car on level ground with the transmission in park and also the emergency brake set as well as the engine is turned off. This is an important step that shouldn’t be ignored!
You might as well need to jack the car up as for removing a tire for testing purposes and jack stands could help you a lot. The process might require you to remove a tire in order to test and replace certain parts as well.
And for the steps on how to test ABS sensor, be guided by the following:
Step 1. Locate and remove the connector.
Look for the electrical connector from the certain wheel speed sensor that is near the frame in the wheel in most cases. You must not be confused by those other wiring harnesses which could lead down to the wheel like the brake pad wear sensor.
If already located, you need to disconnect the wire of the sensor at the connector through freeing the safety clasp and dragging it apart gently.
Step 2. Set up the voltmeter.
With the use of voltmeter having alligator clips, attach the voltmeter leads to the sensor. You must make sure that these test probes must not touch together or the sensor wouldn’t be tested properly.
You must not also use those handheld probes since they could wiggle making the voltmeter readings to fluctuate that makes the process of testing a lot more difficult and could also offset the test.
If the leads have already been connected, set the meter to the AC alternating current voltage.
This meter would show AC voltage by the wave symbol in most cases. If the meter is turned on, it would swing down to zero volts. And now, the sensor is ready to be tested.
Step 3. Perform test.
As you observe the voltmeter, spin the hub or the wheel to create voltage. This will vary based on the speed in which the hub or the wheel is spun. Once the hub starts to spin, this voltage will rise and decrease once it stops.
Now, spin the axle or hub slowly that will produce the voltage. Once no readings could be found, the sensor has failed and so there is a need for a replacement.
Then, the ring should be rotated slowly in order to check whether there is a missing teeth or a possible damage. Known to be magnetic, wheel sensors should be checked for the metal shavings that might hinder performance around the sensor.
Once you’ve gone through all the steps and still there is a code for one of the sensors, the only other thing possible is an open circuit anywhere in the wiring that could be found by a pin to pin check that test the wiring.
Apart from that, you should also need to use a certain wiring diagram together with a voltmeter being set to ohms of resistance as for checking every wire from one end to another. This will definitely help in detecting a broken or a shorted wire, if repaired it must turn its light off.
Are you now equipped with the needed information about ABS sensor and how to test it right? I hope so you are! But take note that you have to be observant as you first drive the car right after testing its ABS system.
Aside from knowing how to test ABS sensor, you should also be cautious and extra careful for your safety. Indeed, testing the ABS sensor is very important as this system plays a crucial role for the entire function of your car.
Good to know that there are guides that will always help you in making the process of testing ABS sensor successful.
You might as well watch this video for additional information.
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Once you’ve gone through all the steps (changed ABS sensor and wheel hub) and still there is a code for one of the sensors, the only other thing possible is an open circuit anywhere in the wiring that could be found by a pin to pin check that test the wiring.
Are you serious? Shouldn’t we check the wires firstly??