23 Jul, 19

What Is An ABS Pump + How Does It Work?

The Anti-Lock Braking System (ABS) & How It Works

Teves MK70 ABS ECU Repairs
The Anti-Lock Braking System or Anti-Skid Braking System is commonly abbreviated as ABS and is an advanced braking technology installed on motor vehicles to prevent the wheels from locking up (ceasing motion) and skidding uncontrollably. It does so by pulsating the braking force delivered to the rear wheels and the front wheels similar to threshold braking, which is a technique commonly used in motor racing and the idea is to control the brake pedal pressure and apply maximum braking force to a point just before the wheels are about to slip.


The ABS system improves vehicle control and will greatly reduce the stopping distance on dry and slippery surfaces, however, it can significantly increase the stopping distance on loose gravel and snow-covered roads where traction between the tyres and road surface is limited.


ESP (Electronic Stability Control) works seamlessly integrated with ABS to further maintain tractive contact with the road surface by electronically controlling the front-to-rear brake bias. The ESP system, depending on the specific capabilities and implementation is also known as Electronic Brakeforce Distribution (EBD), Traction Control System (TCS), Electronic Stability Control (ESC) and Dynamic Traction Control (DTC).

Components of an ABS System

There are four main components that make up an ABS system; wheel speed sensors, hydraulic valves, a pump and an ABS controller, which is also known as an ABS Module or ABS ECU.

Wheel Speed Sensors

The wheel speed sensor is used to determine the acceleration or deceleration of the wheel. These sensors use an ABS ring / reluctor ring which spins with the wheel/differential and creates a magnetic field around the wheel speed sensor, which in turn will generate the voltage in the sensor.

Hydraulic Valves

In each of the brake lines, there is a hydraulic valve which is controlled by the ABS module. On some setups, the valve will have three positions:

  • Position One – The valve is open and any pressure from the brake master cylinder passes directly through to the brake.
  • Position Two – The valve is closed, blocking the brake line and isolating the brake from the master cylinder. This prevents the pressure from rising further if the driver presses harder on the brake pedal.
  • Position Three – The valve opens partially, releasing some of the pressure from the brake.

The majority of issues with the valve system occur because of clogged valves. A clogged inoperable valve will be unable to open, close or change position and the system will fail in trying to modulate the valves and control the pressure supplied to the brakes.

ABS Pump

The pump in the ABS unit is used to restore the loss in pressure to the hydraulic brakes after the hydraulic valves have released it. Signals from the wheel speed sensors are processed by the ABS ECU Module and if a wheel slip is detected, the module will signal the valve to be released to avoid the wheel slip. After the valve is released and the pressure is lost, the pump is used to restore the lost pressure to the braking system. The ABS controller will modulate the status of the pump to control and provide the desired amount of pressure and reduce slipping.

ABS ECU / ABS Module / ABS Controller

The ABS controller, also commonly known as an ABS ECU receives input signals from all the wheel speed sensors and can interpret the information received to identify if there is a wheel slip on any one wheel. If wheel spin is detected and a wheel loses traction, the controller will limit the braking force (EBD) and send the signal to actuate the hydraulic braking valves on and off.


Symptoms Of A Failing ABS Pump

Fortunately, there are signs that you can use to detect whether your ABS pump is failing.


ABS Warning Light or Engine Light: This is the most common sign that you have an issue with your pump. If you have an ABS orange light illuminated on the drivers’ control panel, you have an issue that needs addressing. If you own an older vehicle, it is possible the check engine light will illuminate instead, to warn you that there may be a problem with the ABS system.


Unresponsive Brake Pedal: If your brake pedal is not as responsive as it used to be, or it takes longer to depress, this can indicate that you have an issue with your pump. Do not leave it until your brake pedals become completely unresponsive, as this is a danger to yourself and other road users.


Forceful Braking: You may find that when you put your foot down on your brake pedal, it requires more force than usual, or that a lighter braking manoeuvre no longer works when you try and stop the vehicle. Having a hard brake pedal is not adequate for safe driving, and your braking distance will be affected as the pressure sensor may be faulty.


Brakes Locking Up: If your brakes are locking up when you driving normally, then there is an issue with your ABS pump. This is because, as we mentioned before, it is designed to ensure that your brakes don’t lock up and there is enough traction between the tyres and the ground.


With this issue, you should immediately get it checked by a professional, especially if you start to hear strange clicking noises.


Speedometer: On rare occasions, the speedometer will show that you are doing 0MPH, or will show you incorrect speeds when you are driving. Usually, this issue is accompanied by the check engine light or the ABS light coming on when you start your engine. However, if you experience this problem and there are no lights illuminated on your dashboard, you should still get your vehicle inspected by a professional.


The ABS Pump + ABS ECU / Module is a very common failing part, which here at Sinspeed we have extensive knowledge in testing and repairing. If your ABS unit has failed, check out our ABS Repair category for some of the most common repairs we perform. The units we provide exceed OE specifications and they come with a lifetime warranty! If you have any questions, you can call us on 0203 815 9441.

Tags : ABS System, How The ABS System Works, Symptoms Of ABS Pump Failure, What Is An ABS Controller, What Is An ABS ECU, What Is An ABS Module, What Is An ABS Pump.
14 thoughts on “What Is An ABS Pump + How Does It Work?
  • I drive a vW Jetta 6 2012 model. Of late it does not release the auto lock. I took the car to the VW agent but they have not been able to identify the problem. Recently it was suggested that I may have to buy a new abs pump even though there is no evidence that the problem is caused by the pump. How can you assist in such a case?
    The other issue is that there is no signal on the dashboard that the brakes are faulty. Even the diagnostic test by the agent does not indicate that there is a fault with the brakes.

    • Hi Trevor

      Thanks for the enquiry,

      We can test the ABS unit and simulate it running as if it were on the vehicle, simulating all driving conditions. We test all units before and after remanufacturing to confirm the fault and that the repair is successful, before returning it with a lifetime warranty for complete peace of mind.

      If the unit is not faulty, we will return it with just a testing fee and return carriage.

      I have sent you an email with full information and pricing. If you have any questions, please reply to the email and we’ll be happy to assist you.

      Kind Regards


  • I have a 2000 528i bmw , my DSC light is on, i replaced the abs module my dsc light is still on. My brake will fade to the floor my scanner will not communicate with the ecu. what is the cost of repair? I’ve already replace the abs module but not the pump unit and will the unit be reprogram. Thank You William

    • Hello William

      Thanks for getting in touch,

      We have sent you an email with full details and pricing about your query.

      Kind Regards


  • What kind of pump should be used in the abs module?
    I mean,
    There are many types of pumps
    Which one will be most compatible for an abs?

    • Hello Manik

      Thanks for getting in touch,

      We have sent you an email to follow up with your query.

      Kind Regards


  • Hi There, My Fiesta ST Mk6 2006 BN06DJF has failed mOT with an ABS Pump failure says the local garage. They are willing to strip the unit off the car for me but want me to help find someone to fix the module. What would be the lead time/cost to repair the pump?

    • Hello William

      Thank you for your enquiry,

      We have sent you an email with full details and pricing.

      Kind Regards



    • Hello Sonny

      Thank you for your enquiry,

      A used unit will have to be coded to the vehicle. I hope this helps.

      Kind Regards


  • Hello,

    I have a 2015 Skoda Octavia RS TDI.
    I have Brake Workshop, ABS, ESC, TMPS lights up every time I start the car. They never go away.

    The dealer says there are no fault codes so he can’t do anything. ABS does not work, but the brake pedal response is normal. Braking performance is normal as well.

    Any idea if this could be a faulty ABS module?


    • Hello Stefan

      Thank you for your enquiry,

      We have sent you an email with full details and pricing.

      Kindest Regards


  • i have a 2011 reanult master lwb. mechanic pus his computer on it sais abs pump, what do i need to do – get it off and send it to you?
    regards Craig
    [email protected] all in lower case

    • Hey Craig!
      Thanks for reaching out to us.
      Your enquiry has been forwarded to the relevant department & they will reach out to you via email.

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